Gene List 2005 for Cucumber

Todd C. Wehner

Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609 U.S.A

Introduction

This is the latest version of the gene list for cucumber (Cucumis sativus L. ). In addition to morphological and resistance genes, this list includes genes that have been cloned from different plant tissues of cucumber. The genes in the list have been grouped into ten categories as follows: seedling markers, stem mutants, leaf mutants, flower mutants, fruit type mutants, fruit color mutants, resistance genes (mostly to diseases), protein (isozyme) variants, DNA (RFLPs and RAPDs) markers (Table 1), and cloned genes (Table 2). There is also a review of linkage of the morphological and resistance genes. Complete lists and updates of genes for have been published previously, as follows:

Previous Gene Lists

• Robinson et al., 1976
• Robinson et al., 1982
• Pierce and Wehner, 1989
• Wehner, 1993
• Wehner and Staub, 1997
• Xie and Wehner, 2001

Revisions to the 2005 cucumber gene list include the addition of Psm for paternal sorting of mitochondria (Havey et al., 2004). Researchers are encouraged to send reports of new genes, as well as seed samples to the cucumber gene curator (Nischit V. Shetty), or to the assistant curator (Todd C. Wehner). Please inform us of omissions or errors in the gene list. Scientists should consult the list as well as the rules of gene nomenclature for the Cucurbitaceae (Robinson et al., 1976; Robinson et al., 1982) before choosing a gene name and symbol. That will avoid duplication of gene names and symbols. The rules of gene nomenclature were adopted in order to provide guidelines for naming and symbolizing genes. Scientists are urged to contact members of the gene list committee regarding rules and gene symbols.

Gene Mutants

Seed and seedling mutants

One of the advantages of using the cucumber in genetic research is the availability of seedling markers. To date, five non-lethal color mutants [virescent (v) (Poole, 1944; Tkachenko, 1935), variegated virescence (vvi) (Abul-Hayja and Williams, 1976), yellow cotyledons-1 (yc-1) (Aalders, 1959), yellow cotyledons-2 (yc-2) (Whelan and Chubey, 1973; Whelan et al., 1975), yellow plant (yp) (Abul-Hayja and Williams, 1976)] and 4 lethal, color mutants [chlorophyll deficient (cd) (Burnham et al., 1966), golden cotyledon (gc) (Whelan, 1971), light sensitive (ls) (Whelan, 1972b), pale lethal (pl) (Whelan, 1973)] have been identified.

Six seedling traits which affect traits other than color include bitterfree (bi) (Andeweg and DeBruyn, 1959), blind, (bl) (Carlsson, 1961), delayed growth (dl) (Miller and George, 1979), long hypocotyl (lh) (Robinson and Shail., 1981), revolute cotyledons (rc) (Whelan et al., 1975) and stunted cotyledons (sc) (Shanmugasundarum and Williams, 1971; Shanmugasundarum et al., 1972).

Stem mutants

Seven genes have been identified which affect stem length:  bush (bu) (Pyzenkov and Kosareva, 1981), compact (cp) (Kauffman and Lower, 1976), determinate (de) (Denna, 1971; George, 1970; Hutchins, 1940), dwarf (dw) (Robinson and Mishanec, 1965), tall height (T) (Hutchins, 1940) and In-de which behaves as an intensifier for de (George, 1970). Rosette (ro) which also affects height is characterized by muskmelon-like leaves (de Ruiter et al., 1980).

Unlike these genes, fasciated (fa) (Robinson, 1978b; Shifriss, 1950) affects stem confirmation, not length.

Leaf mutants

Several genes have been shown to control leaf or foliage characteristics. Eight in particular are responsible for leaf shape: blunt leaf apex (bla) (Robinson, 1987a), cordate leaves-1 (cor-1) (Gornitskaya, 1967), cordate leaves-2 (cor-2) (Robinson, 1987c), crinkled leaf (cr) (Odland and Groff, 1963a), divided leaf (dvl) (den Nijs and Mackiewicz, 1980), ginko leaf (gi) (John and Wilson, 1952), little leaf (ll), (Goode et al., 1980; Wehner et al., 1987) and umbrella leaf (ul) (den Nijs and de Ponti 1983). Note that ginko leaf is a misspelling of the genus Ginkgo.

The original cordate leaf gene identified by Gornitskaya (1967) differs from cor proposed by (Robinson, 1987c) which also had calyx segments which tightly clasp the corolla, hindering flower opening and insect pollination. Therefore, we propose that the first gene identified by Gornitskaya be labeled cor-1 and the second identified by Robinson be labeled cor-2. It should be noted that plants with stunted cotyledon may look similar to those with ginko at the younger stages but the cotyledons of sc mutants are irregular and gi mutants are sterile.

Opposite leaf arrangement (opp) is inherited as a single recessive gene with linkages to m and l. Unfortunately, incomplete penetrance makes the opposite leaf arrangement difficult to distinguish from normal plants with alternate leaf arrangement (Robinson, 1987e).

Five mutants which affect color or anatomical features of the foliage are golden leaves (g) (Tkachenko, 1935), glabrous (gl) (Inggamer and de Ponti, 1980; Robinson and Mishanec, 1964), glabrate (glb) (Whelan, 1973), short petiole (sp) (den Nijs and Boukema, 1985) and tendrilless (td) (Rowe and Bowers, 1965).

Flower mutants

Sex expression in cucumber is affected by several single-gene mutants. The F locus affects gynoecy (femaleness), but is modified by other genes and the environment, and interacts with a and m (androecious and andromonoecious, respectively) (Galun, 1961; Kubicki, 1969; Rosa, 1928; Shifriss, 1961; Tkachenko, 1935; Wall, 1967). Androecious plants are produced if aa and ff occur in combination, otherwise plants are hermaphroditic if mm FF, andromonoecious if mm ff, gynoecious if MM FF and monoecious if MM ff. The gene F may also be modified by an intensifier gene In-F which increases the femaleness (Kubicki, 1969b). Other genes that affect sex expression are gy for gynoecious (Kubicki, 1974), m-2 for andromonoecious (Kubicki, 1974) and Tr for trimonoecious expression (Kubicki, 1969d).

Cucumbers, typically considered day-neutral plants, have occasionally been shown to express sensitivity to long days. Della Vecchia et al. (1982) and Shifriss and George (1965) demonstrated that a single gene for delayed flowering (df) is responsible for this short-day response.

Another gene which may give the impression of eliciting daylength sensitivity by causing a delay in flowering is Fba. In reality, Fba triggers flower bud abortion prior to anthesis in 10 to 100% of the buds (Miller and Quisenberry, 1978).

Three separate groups have reported single genes for multiple pistillate flowers per node. Nandgaonkar and Baker (1981) found that a single recessive gene mp was responsible for multiple pistillate flowering. This may be the same gene which Fujieda et al. (1982) later labeled as pf for plural pistillate flowering. However, they indicated that 3 different alleles were responsible, with single pistillate being incompletely dominant over multiple pistillate: pf ⁺ for single pistillate, pf ^d for double pistillate and pf ^m for multiple pistillate (more than 2 flowers per node).

Thaxton (1974), reported that clustering of pistillate flowers is conditioned by a single dominant gene (we propose the symbol, Mp-2), and that modifier genes influence the amount of clustering. Thaxton (1974) also determined that clustering of perfect flowers is controlled by genes different from clustering of gynoecious flowers.

Several genes for male sterility have been reported for cucumber, but because of the ease of changing sex expression with growth regulators, little commercial use has been made of them. Five genes, ms-1, ms-2, ap, cl and gi have been identified. The genes ms-1 and ms-2 cause sterility by pollen abortion before anthesis; ms-1 plants are also partially female sterile (Robinson and Mishanec, 1965; Shanmugasundarum and Williams, 1971; Whelan, 1972a). Apetalous mutants (ap) on the other hand have infertile anthers which appear to have been transformed into sepal-like structures (Grimbly, 1980). Ginko (gi), mentioned earlier as a leaf mutant, also causes male sterility (John and Wilson, 1952).

One of these male steriles may be of little use except as a genetic marker. Closed flower (cl) mutants are both male and female sterile, so seed production must be through the heterozygotes only (Groff and Odland, 1963). With this mutant, the pollen is inaccessible to bees because the buds remain closed.

Three genes alter floral characteristics: green corolla (co) (Currence, 1954; Hutchins, 1935), orange-yellow corolla (O) (Tkachenko 1935), negative geotropic peduncle response (n) (Odland and Groff, 1963b). Green corolla (co), named because of its green petals, has enlarged but sterile pistils (Currence, 1954; Hutchins, 1935), and has potential for use as a female sterile in hybrid production.

Fruit mutants

Because the fruit is the most important part of the cucumber economically, considerable attention has been given to genes affecting it. One such gene is Bitter fruit, Bt, (Barham, 1953) which alters fruit flavor by controlling cucurbitacin levels. The gene Bt is different from bi because it consistently alters only the fruit cucurbitacin levels compared to bi which affects the whole plant.

Five genes conditioning skin texture are Tu (Strong, 1931; Wellington, 1913), te (Poole, 1944; Strong, 1931), P (Tkachenko, 1935), I (Tkachenko, 1935) and H (Hutchins, 1940; Tkachenko, 1935). Smooth (Tu) and tender (te) skin are usually associated with European types, while American types are generally warty and thick skinned (Poole, 1944; Strong 1931). Heavy netting, H, which occurs when fruit reach maturity may be tightly linked or pleiotropic with R and B (discussed later).

In Cucumis sativus var. tuberculatus, Tkachenko (1935) found that gene P, causing fruit with yellow rind and tubercles, was modified by gene I, an intensifier which increases the prominence of the tubercles (Tkachenko, 1935).

There are 3 genes which affect internal fruit quality, each identified by viewing transections of fruits; Empty chambers-1 (Es-1), Empty chambers-2 (Es-2) (Kubicki and Korzeniewska, 1983) and locule number (l) (Youngner, 1952).

Hutchins (1940) proposed that 2 genes controlled spine characteristics, with f producing many spines and being tightly linked with s which produced small spines. Poole (1944) used the data of Hutchins (1940) to suggest that s and f were the same gene and proposed the joint symbol s for a high density of small spines. Tkachenko (1935) who used the same symbol for control of less dense spines, did not look at spine size, and the same gene might have been involved. However, Fanourakis (1984) and Fanourakis and Simon (1987) reported 2 separate genes involved, and named them ss and ns for small spines and numerous spines, respectively.

These may differ from those that led Carruth (1975) to conclude that 2 genes act in a double recessive epistatic fashion to produce the dense, small spine habit. We propose that these genes be labeled s-2 and s-3 and s1 be used instead of s proposed by Poole (1944).

Carruth (1975) and Pike and Carruth (1977) also suggested that carpel rupture along the sutures was inherited as a single recessive gene that was tightly linked with round, fine-spined fruits. This may be similar to what Tkachenko (1935) noted in the 'Klin mutant' as occasional deep-splitting flesh. We suggest the symbol cs for carpel splitting, but note that because penetrance of the trait may be lower under certain environmental conditions (Carruth, 1975) this trait may be related to the gooseberry (gb) fruit reported by Tkachenko (1935). Another character not found in commercial cultivars was protruding ovary (pr) reported by Youngner (1952).

There is dispute over the inheritance of parthenocarpy, a trait found in many European cucumbers (Wellington and Hawthorn, 1928). Pike and Peterson (1969) suggested an incompletely dominant gene, Pc, affected by numerous modifiers, was responsible. In contrast, de Ponti and Garretsen (1976) explained the inheritance by 3 major isomeric genes with additive action.

A modifier of fruit length, Fl, was identified by its linkage with scab resistance (Cca) (Henry Munger, personal communication; Wilson, 1968). Expressed in an additive fashion, fruit length decreases incrementally from heterozygote to homozygote (fl fl).

Fruit Color

Twelve mutants have been identified which affect fruit color either in the spines, skin, or flesh and a few of these appear to act pleiotropically. For example, R for red mature fruit color is very closely linked or pleiotropic to B for black or brown spines and H for heavy netting (Hutchins, 1935; Tkachenko, 1935; Wellington, 1913). It also interacts with c for cream colored mature fruit in such a way that plants which are (RR CC), (RR cc), (rr CC) and (rr cc) have red, orange, yellow and cream colored fruits, respectively (Hutchins, 1940).

The B gene produces black or brown spines and is pleiotropic to or linked with R and H (Wellington, 1913). The homozygous recessive plant is white spined with cream colored mature fruit and lacks netting. Other spine color genes are B-2, B-3 and B-4 (Cowen and Helsel, 1983; Shanmugasundarum et al., 1971a).

White immature skin color (w) is recessive to the normal green (Cochran, 1938), and yellow green (yg) is recessive to dark green and epistatic with light green (Youngner, 1952). Skin color may also be dull or glossy (D) (Strong, 1931; Tkachenko, 1935) and uniform or mottled (u) (Andeweg, 1956; Strong, 1931).

Kooistra (1971) reported 2 genes that affect fruit mesocarp color. White flesh (wf) and yellow flesh (yf) gene loci interact to produce either white (WfWf YfYf or wfwf YfYf), yellow (WfWf yfyf), or orange (wfwf yfyf) flesh color.

Insect Resistance

Bitterfree, bi (Andeweg and DeBruyn, 1959), is responsible for resistance to spotted and banded cucumber beetles (Diabrotica spp. ) (Chambliss, 1978; Da Costa & Jones, 1971a; Da Costa & Jones, 1971b) and two-spotted spider mites (Tetranychus urticae Koch. ) (Da Costa & Jones, 1971a; Soans et al., 1973). However, this gene works inversely for the 2 species. The dominant allele which conditions higher foliage cucurbitacin levels incites resistance to spider mites by an antibiotic affect of the cucurbitacin. The homozygous recessive results in resistance to cucumber beetles because cucurbitacins are attractants.

In the 1989 Cucurbit Genetics Cooperative Report the authors labeled the gene for resistance to Diabrotica spp. di, but wish to retract it in light of recent evidence.

Disease Resistance

Currently there are 15 genes known to control disease resistance in C. sativus. Three of these condition virus resistance. Wasuwat and Walker (1961) found a single dominant gene, Cmv, for resistance to cucumber mosaic virus. However, others have reported more complex inheritance (Shifriss et al., 1942). Two genes condition resistance to watermelon mosaic virus, Wmv (Cohen et al, 1971) and wmv-1-1 (Wang et al., 1984). Most recently, resistance to zucchini yellow mosaic virus (zymv) has been identified (Provvidenti, 1985).

Both resistance to scab, caused by Cladosporium cucumerinum Ell. & Arth., and resistance to bacterial wilt caused by Erwinia tracheiphila (E. F. Smith) Holland are dominant and controlled by Ccu (Abul-Hayja et al., 1978; Andeweg, 1956; Bailey and Burgess, 1934) and Bw (Nuttall and Jasmin, 1958; Robinson and Whitaker, 1974), respectively. Other dominant genes providing resistance are: Cca for resistance to target leaf spot (Corynespora cassiicola) (Abul-Hayja et al., 1978), Cm for resistance to Corynespora blight (Corynespora melonis) (van Es, 1958), Foc for resistance to Fusarium wilt (Fusarium oxysporum f. sp. cucumerinum) (Netzer et al., 1977) and Ar for resistance to anthracnose [Colletotrichum lagenarium (Pars. ) Ellis & Halst. ] (Barnes and Epps, 1952). In contrast, resistance to Colletotrichum lagenarium race 1 (Abul-Hayja et al., 1978) and angular leaf spot (Pseudomonas lachrymans) (Dessert et al., 1982) are conditioned by the recessive genes cla and psl, respectively.

Several reports have indicated that more than one gene controls resistance to powdery mildew [Sphaerotheca fuliginea (Schlecht) Poll. ] with interactions occurring among loci (Hujieda and Akiya, 1962; Kooistra, 1968; Shanmugasundarum et al., 1971b). The resistance genes pm-1 and pm-2 were first reported by Hujieda and Akiya (1962) in a cultivar which they developed and named 'Natsufushinari'. Kooistra (1968) using this same cultivar, later confirmed their findings and identified one additional gene (pm-3) from USDA accessions PI200815 and PI200818. Shimizu et al. (1963) also supported 3 recessive genes which are responsible for resistance of 'Aojihai' over 'Sagamihan'.

Several genes with specific effects have been identified more recently (Shanmugasundarum et al., 1971b) but unfortunately, direct comparisons were not made to see if the genes were identical with pm-1, pm-2 and pm-3. Fanourakis (1984) considered a powdery mildew resistance gene in an extensive linkage study and proposed that it was the same gene used by Shanmugasundarum et al. (1971b) which also produces resistance on the seedling hypocotyl. Because expression is identified easily and since it is frequently labeled in the literature as 'pm' we believe that this gene should be added to the list as pm-h with the understanding that this may be the same as pm-1, pm-2 or pm-3.

Currently, one gene, dm, has been identified which confers resistance to downy mildew [Pseudoperonospora cubensis (Berk. & Curt. ) Rostow] (van Vliet and Meysing, 1974). Inherited as a single recessive gene, it also appeared to be linked with pm (van Vliet, 1977). There are, however, indications that more than one gene may be involved (Jenkins, 1946).

Environmental Stress Resistance

Presently, only 2 genes have been identified in this category; resistance to sulfur dioxide air pollution conditioned by Sd (Bressan et al., 1981) and increased tolerance to high salt levels conditioned by major gene, sa, Jones (1984).

Other Traits

The dominant allele, Psm, induces paternal sorting of mitochondria, where Psm is from MSC 16 and psm is from PI 401734 (Havey et al., 2004).

Molecular and Protein Markers

Isozyme variant nomenclature for this gene list follows the form according to Staub et al. (Staub et al., 1985), such that loci coding for enzymes (e.g. glutamine dehydrogenase, G2DH) are designated as abbreviations, where the first letter is capitalized (e.g. G2dh). If an enzyme system is conditioned by multiple loci, then those are designated by hyphenated numbers, which are numbered from most cathodal to most anodal and enclosed in parentheses. The most common allele of any particular isozyme is designated 100, and all other alleles for that enzyme are assigned a value based on their mobility relative to that allele. For example, an allele at locus 1 of FDP (fructose diphosphatase) which has a mobility 4 mm less that of the most common allele would be assigned the designation Fdp(1)-96.

RFLP marker loci were identified as a result of digestion of cucumber DNA with DraI, EcoRI, EcoRV, or HindIII (Kennard et al., 1994). Partial-genomic libraries were constructed using either PstI-digested DNA from the cultivar Sable and from EcoRV­digested DNA from the inbred WI 2757. Derived clones were hybridized to genomic DNA and banding patterns were described for mapped and unlinked loci (CsC482/H3, CsP314/E1, and CsP344/E1, CsC477/H3, CsP300/E1).

Clones are designated herein as CsC = cDNA, CsP = PstI-genomic, and CsE = EcoRI-genomic. Lower-case a or b represent two independently-segregating loci detected with one probe. Lower-case s denotes the slowest fragment digested out of the vector. Restriction enzymes designated as DI, DraI; EI, EcoRI; E5, EcoRV; and H3, HindIII. Thus, a probe identified as CsC336b/E5 is derived from a cDNA library (from 'Sable') which was restricted using the enzyme EcoRV to produce a clone designated as 336 which displayed two independently segregating loci one of which is b. Clones are available in limited supply from Jack E. Staub.

RAPD marker loci were identified using primer sequences from Operon Technologies (OP; Alameda, California, U.S.A. ) and the University of British Columbia (Vancouver, BC, Canada). Loci are identified by sequence origin (OP or BC), primer group letter (e.g., A), primer group array number (1-20), and locus (a, b, c, etc. ) (Kennard et al., 1994). Information regarding unlinked loci can be obtained from Jack E. Staub.

Because of their abundance, common source (two mapping populations), and the accessibility of published information on their development (Kennard et al., 1994) DNA marker loci are not included in Table 1, but are listed below.

The 60 RFLP marker loci from mapping cross Gy 14 x PI 183967 (Kennard et al., 1994): CsP129/E1, CsC032a/E1, CsP064/E1, CsP357/H3, CsC386/E1, CsC365/E1, CsP046/E1, CsP347/H3, CsC694/E5, CsC588/H3, CsC230/E1, CsC593/D1, CsP193/H3, CsP078s/H3, CsC581/E5, CsE084/E1, CsC341/H3, CsP024/E1, CsP287/H3, CsC629/H3, CsP225s/E1, CsP303/H3, CsE051/H3, CsC366a/E5, CsC032b/E1, CsP056/H3, CsC378/E1, CsP406/E1, CsP460/E1, CsE060/E1, CsE103/E1, CsP019/E1, CsP168/D1, CsC560/H3, CsP005/E1, CsP440s/E1, CsP221/H3, CsC625/E1, CsP475s/E1, CsP211/E1, CsP215/H3, CsC613/E1, CsC029/H3, CsP130/E1, CsC443/H3, CsE120/H3, CsE031/H3, CsC366b/E5, CsC082/H13, CsP094/H3, CsC362/E1, CsP441/E1, CsP280/H3, CsC137/H3, CsC558/H3, CsP037a/E1, CsP476/H3, CsP308/E1, CsP105/E1, and Csc166/E1.

The 31 RFLP marker loci from mapping cross Gy 14 x PI 432860 (Kennard et al., 1994): CsC560/D1, CsP024/E5, CsP287/H3, CsC384/E5, CsC366/E5, CsC611/D1, CsP055/D1, CsC482/H3, CsP019/E1, CsP059/D1, CsP471s/H13, CsC332/E5, CsP056/H3, CsC308/E5, CsP073/E5, CsP215/H3, CsC613/D1, CsP266/D1, CsC443/H3, CsE031/E1, CsE120/H3, CsE063/E1, CsP444/E1, CsC612/D1, Cs362/E1, CsP280/H3, CsC558/H3, CsP008/D1, CsP308/E1, CsC166/E1, and CsP303/H3.

The 20 RAPD marker loci from mapping cross Gy 14 x PI 432860 (Kennard et al., 1994): OPR04, OPW16, OPS17, OPE13a, OPN06, OPN12, OPP18b, BC211b, OPN04, OPA10, OPE09, OPT18, OPA14b, OPU20, BC460a, OPAB06, OPAB05, OPH12, OPA14a, and BC211a.

In addition to the isozymes, RFLPs and RAPDs, nearly 100 cloned genes are listed here (Table 2).

Possible Allelic or Identical Genes

Several of the genes listed may be either pleiotropic, closely linked, or allelic. Additional research is needed to compare the sources of the various similar genes to ensure that they are not duplicates. In some instances this may be difficult because many of the earlier publications did not list the source of the genes or the methods used to measure the traits, and many of these authors are deceased.

An example of this is the two-locus model (R c) for fruit color. We have been unable to locate any plants with red or yellow colored mature fruits. All plants evaluated in other studies have color inherited as a single gene. Hutchins may have separated fruit with cream color into 2 groups, yellow and cream, and fruits with orange color into two groups, orange and red. However, those distinctions are difficult to make using available germplasm. Situations like these may be impossible to resolve.

In the future, researchers should use the marker lines listed here, or describe and release the marker lines used so that allelism can be checked by others. Currently, groups of similar genes that need to be checked to determine how they are related include the following: the chlorophyll deficiency mutants (cd, g, ls, pl, v, vvi, yc-1, yc-2, and yp), the stem mutants (bu, de, dw, In-de, and T), the leaf shape mutants (rc and ul), the sex expression mutants (a, F, gy, In-F, m, m2, and Tr), the male sterility genes (ap, cl, ms-1, and ms-2), the flowering stage mutants (df and Fba), the flower color mutants (co and O), the powdery mildew resistance mutants (pm-1, pm-2, pm-3 and pm-h), the fruit spine color mutants (B, B-2, B-3, and B-4), the fruit skin color mutants (c, R, and w), the spine size and density mutants (s, s2, and s-3) and the seed cell mutants (cs and gb).

Two groups of associated traits, one from 'Lemon' cucumber (m, pr, and s) and the other involving fruit skin color, surface texture, and spine type (R, H, and B), need to be checked using large populations to determine whether they are linked or pleiotropic. Recent gains have been made in this area by Robinson (1978a) who demonstrated that the m gene is pleiotropic for fruit shape and flower type, producing both perfect flowers and round fruits, and Abul-Hayja et al. (1975) and Whelan (1973) who determined that gl and glb are independent genes.

New information indicates that comparisons also need to be made between resistance to scab (Ccu) and Fusarium wilt (Foc) and between resistance to target leaf spot (Cca) and Ulocladium cucurbitae leafspot. Mary Palmer (personal communication) found a fairly consistent association between resistances to scab and Fusarium wilt, which suggests that they might be linked or using the same mechanism for defense against the pathogen.

Similar defense mechanisms might also be responsible for similarities in resistance to target leaf spot (Cca) and Ulocladium cucurbitae leafspot (Henry Munger, personal communication).

Genetic Linkage

Since cucumber has just 7 chromosome pairs and over 100 known genes, it would seem that linkage maps would be fairly complete by now. Unfortunately, we know of few references reporting linkages of more than 2 gene loci, and this is the first review to summarize the literature for linkages and attempt to describe different linkage groups.

Many difficulties were encountered and should be considered when reading this review. First, a portion of the nomenclature is still unclear and some of the genes may be duplicates of others since common parents were not compared. This problem was discussed in the previous section. Secondly, some of the linkage relationships analyzed in previous studies did not involve specific genes. Linkages in several reports were discussed for plant traits that might have been inherited in multigenic fashion, or if a single gene were involved, it was not specifically identified.

Therefore, in this review linkages for traits without genes will be omitted and a '?' will follow each gene which has a questionable origin. Six linkage groups could be determined from the current literature (Fig. 1). The order in which the genes were expressed in each group does not necessarily represent the order in which they may be found on the chromosome.

Linkage Group A

The largest linkage group in cucumber has 12 genes, composed of wmv-1-1, gy, gl, dl, dvl, de, F, ms-2, glb, bi, df and B-3 or B-4. In contributing to this grouping, Whelan (1974) noted that ms-2 is linked with glb (rf=.215+.029) and de (rf=.335+.042) while being independent of bi, gl, yc-1, yc-2, and cr. Gene de is linked with F (Odland and Groff, 1963b; Owens and Peterson, 1982) which in turn is linked with B-3 or B-4 (Cowen and Helsel, 1983), gy (rf=.04) (Kubicki, 1974), bi (rf=.375) and df (rf=34.7) (Fanourakis, 1984; Fanourakis and Simon, 1987). Gene de is also weakly linked with dl (Miller and George, 1979), strongly linked with dvl (Netherlands, 1982), and independent of cp (Kauffman and Lower, 1976). Gene wmv-1-1 is linked with bitterfree (bi) but independent of Ccu, B, F or pm? (Wang et al., 1987).

Two reports show that dvl is weakly linked with gl (rf=.40) and independent of bi and Ccu (Netherlands, 1982; den Nijs and Boukema, 1983), while Robinson (1978f) originally indicated that gl was linked with yc and independent of B, m, l, and yg as well as bi (Netherlands, 1982) and sp (den Nijs and Boukema, 1985), but more recently he indicated that gl was independent of yc (Robinson, 1987d).

Completing linkage group I, Cowen and Helsel (1983) demonstrated that the spine color genes (B-3 and B-4) were independent of the genes for bitterness, and Whelan (1973) found that pl was independent of glb and bi, while glb was independent of gl, bi, ls, yc, and cr. The last clarifies that gl and glb must indeed be separate loci.

Linkage Group B

Group II is composed of 9 genes (n, pr, l, m, opp, m-2, Bw, s? and ms?) unless s? (Robinson, 1978) is the same as s from Hutchins (1940) and Poole (1944). If these are the same, then linkage groups II and III will be joined for a total of 12 genes. Of the first 7, two pairs have been defined with recombination values. Youngner (1952) determined that m and l were linked with a recombination frequency of .326 + .014 and Robinson determined that opp was linked to both (Robinson, 1987e). Iezzoni and Peterson (1979, 1980) found that m and Bw were separated by only one map unit (rf=.011+.003). Iezzoni et al. (1982) also determined that m-2 was closely linked with both m and Bw, and that Bw was independent of F from linkage group I (Iezzoni and Peterson, 1980).

Robinson (1978c, 1978d), and Youngner (1952) found that linkages existed between m, l, n, pr and spine number (s?) with the possibility of pleiotropy being responsible for the m/pr relationship. They also demonstrated that B, yg, and pm? were independent of the same genes (Robinson, 1978c; Youngner, 1952).

Rounding out the linkage group is one of the male sterility genes (ms?). Robinson (1978d) found that it was linked with both m and l, but did not identify which male sterile gene it was.

Linkage Group C

Group III is the oldest and most mystifying linkage group. It is currently composed of R for red or orange mature fruit color, H for heavy netting, B for black or brown spine color, c for cream mature fruit color and s for spine frequency and size (Hutchins, 1940; Poole, 1944; Strong, 1931; Tkachenko, 1935). However, there is speculation on the nature of this linkage group. Since very few recombinants of the R, H, B and c, h, b linkage groups have been reported, it is also felt that these characteristics may be the response of 2 alleles at a single pleiotropic gene. There is also speculation that R and c are different alleles located at the same locus (see earlier discussion).

Hutchins (1940) found that s was independent of B and H while s was linked with R and c. If he was correct, then pleiotropy of H and B with R and c is ruled out. His report also indicated that B and s were independent of de as was de of R, c and H.

A possibility exists that this linkage group may be a continuation of group II through the s gene. Poole (1944) used the data of Hutchins (1940) to determine that c and s are linked with a recombination frequency of .163 + .065. The question that remains is whether s (Hutchins, 1940; Poole, 1944) is the same as the gene for spine number in the findings of Robinson (1978c). If Cowen and Helsel (1983) are correct in their finding that a linkage exists between F and B then groups I and III may be on the same chromosome. However, in this text they will remain separated based on conclusions of Fanourakis (1984) which indicate that errors may be common when attempting to distinguish linkages with F since classification of F is difficult. This difficulty may also explain many conflicting reports.

Linkage Group D

Twelve genes (ns, ss, Tu, Pc, D, U, te, cp, dm, Ar, coca and pm? or pm-h) are in group IV, but the identity of the specific gene for powdery mildew resistance is elusive. Van Vliet and Meysing (1947, 1977) demonstrated that the gene for resistance to downy mildew (dm) was either linked or identical with a gene for resistance to powdery mildew (pm?), but because the linkage between pm? and D was broken while that of dm and D was not, pm? and dm must be separate genes. The problem lies in the lack of identity of pm? because Kooistra (1971) also found that a gene for powdery mildew resistance (pm?) was linked to D.

Further complicating the identity of pm, Fanourakis (1984) found that pm-h was linked to te and dm, yet cp, which must be located at approximately the same locus, was independent of te. He suggested that there were either 2 linkage groups, ns, ss, Tu, Pc, D, U, te and cp, dm, Ar, located at distal ends of the same chromosome with pm-h at the center, or the 2 groups are located on different chromosomes with a translocation being responsible for apparent cross linkages. However, evidence for the latter which suggested that F was associated with the 7-gene segment is not probable since there are few other supportive linkages between genes of this segment and linkage group I. A more likely explanation is the occurrence of 2 or more genes conditioning resistance to powdery mildew being found on this chromosome.

More recently Lane and Munger (1985) and Munger and Lane (1987) determined that a gene for resistance to powdery mildew (pm?) was also linked with coca for susceptibility to target leaf spot but that linkage, though fairly tight, was breakable.

The last 4 genes in this group are Tu, D, te and u (Strong, 1931). Until recently it was believed that each in the recessive form were pleiotropic and consistent with European type cucumbers and each in the dominant form were pleiotropic and consistent with American type cucumbers. Fanourakis (1984) and Fanourakis and Simon (1987) reported that crossing over (R=23.7) occurred between te and the other 3 genes which still appeared to be associated. However, using triple backcrosses they demonstrated that there is a definite order for Tu, D and u within their chromosome segment and that the Tu end is associated with the ns and ss end.

Linkage Group E

Group V is currently composed of 3 genes lh, sp and ul. The gene sp was strongly linked with lh and weakly linked with ul (Zijlstra and den Nijs, 1986). However Zijlstra and den Nijs (1986) expressed concern for the accuracy of the sp and ul linkage data since it was difficult to distinguish ul under their growing conditions.

Linkage Group F

Group VI is comprised of 2 genes, Fl and Ccu which appear to be tightly associated. Wilson (1968) concluded that pleiotropy existed between scab resistance and fruit length because backcrossing scab resistance into commercial varieties consistently resulted in reduced fruit length. However, Munger and Wilkinson (1975) were able to break this linkage producing varieties with scab resistance and longer fruit (Tablegreen 65 and 66, Marketmore 70 and Poinsett 76). Now when these varieties are used to introduce scab resistance long fruit length is consistently associated.

Unaffiliated Genes

Independent assortment data are as important in developing linkage maps as direct linkage data and several researchers have made additional contributions in this area. One of the most extensive studies, based on the number of genes involved, is by Fanourakis (1984). He indicated that Ar was independent of df, F, ns, B, u, mc, pm, Tu, and D; dm was independent of bi, df, F, ns, ss, B, te, u, mc, Tu and D; bi was independent of cp, df, B, pm-h, te, u, mc and Tu; cp was independent of df, F, ns, ss, te, u, Tu, and D; F was independent of sf, B, pm-h, te, u, mc, Tu and D; df was independent of te, u, Tu, and D; ns was independent of B, pm-h and mc; ss was independent of B and mc; and B is independent of pm-h, te, u, Tu and D.

Two other extensive studies indicated that yc-2 was not linked with rc, yc-1, de, bi, cr, glb, gl, and m, (Whelan et al., 1975) and both Ccu and Bw were independent of bi, gl, glb, ls, rc, sc, cr, mc, gy-1 and gy-2 (Abul-Hayja et al., 1975). Meanwhile, white immature fruit color (w) was inherited independently of black spines (B), and locule number (l) (Cochran, 1938; Youngner, 1952).

Whelan (1973) found that light sensitive (ls) was not linked with nonbitter (bi?) but did not indicate which bitter gene he used. Zijlstra (1987) also determined that bi was independent of cp, gl is independent of lh and ccu is independent of lh, ro and cp.

Powdery mildew has been the subject of several linkage studies. Robinson (1978e) indicated that resistance in 'Ashley' which contains 3 recessive factors was independent of B, l, pr, yg, fa, s, and H. Kooistra (1971) found that powdery mildew resistance was not linked with yf or wf and Barham (1953) determined that the resistance genes in USDA PI 173889 were independent of Bt.

Like linkage data, independent assortment data may be very valuable in developing gene maps, but care must be taken when utilizing them. For example, resistance to powdery mildew was demonstrated in the previous paragraph but none of the researchers were able to identify the particular gene involved.

Table 1. The qualitative genes of cucumber.

^zAsterisks on cultigens and associated references indicate the source of information for each. ^y W = Mutant available through T.C. Wehner, cucumber gene curator for the Cucurbit Genetics
Cooperative; P = mutants are available as standard cultivars or accessions from the Plant
Introduction Collection; ? = availability not known; L = mutant has been lost.
^* Isozyme nomenclature follows a modified form of Staub et al. (1985) previously described by
Richmond (1972) and Gottlieb (1977).

Table 2. The cloned genes of cucumber and their function.^z

^zOnly the sequences published in both journals and the genebank database are listed.

Literature Cited

1. Aalders, L. E. 1959. 'Yellow Cotyledon', a new cucumber mutation. Can. J. Cytol. 1:10-12.
2. Abul-Hayja, Z. and P. H. Williams. 1976. Inheritance of two seedling markers in cucumber. HortScience 11:145.
3. Abul-Hayja, Z., P. H. Williams, and C. E. Peterson. 1978. Inheritance of resistance to anthracnose and target leaf spot in cucumbers. Plant Dis. Rptr. 62:43-45.
4. Abul-Hayja, Z., P. H. Williams, and E. D. P. Whelan. 1975. Independence of scab and bacterial wilt resistance and ten seedling markers in cucumber. HortScience 10:423¬ 424.
5. Ahnert, V., C. May, R. Gerke, and H. Kindl. 1996. Cucumber T-complex protein. Molecular cloning, bacterial expression and characterization within a 22-S cytosolic complex in cotyledons and hypocotyls. European J. of Biochemi. 235:114-119.
6. Aleksandrov, S. V. 1952. The use of hybrid seed for increasing cucumber yields in greenhouses (in Russian). Sad. I. ogorod. 10:43-45.
7. Andeweg, J. M. 1956. The breeding of scab-resistant frame cucumbers in the Netherlands. Euphytica 5:185-195.
8. Andeweg, J. M. and J. W. DeBruyn. 1959. Breeding non-bitter cucumbers. Euphytica 8:13-20.
9. Atsmon, D. and C. Tabbak. 1979. Comparative effects of gibberellin, silver nitrate and aminoethoxyvinyl-glycine on sexual tendency and ethylene evolution in the cucumber plant (Cucumis sativus L. ). Plant and Cell Physiol. 20:1547-1555.
10. Bailey, R. M. and I. M. Burgess. 1934. Breeding cucumbers resistant to scab. Proc. Amer. Soc. Hort. Sci. 32:474-476.
11. Barham, W. S. 1953. The inheritance of a bitter principle in cucumbers. Proc. Amer. Soc. Hort. Sci. 62:441-442.
12. Barnes, W. C. and W. M. Epps. 1952. Two types of anthracnose resistance in cucumbers. Plant Dis. Rptr. 36:479-480.
13. Bressan, R. A., L. LeCureux, L. G. Wilson, P. Filner, and L. R. Baker. 1981. Inheritance of resistance to sulfur dioxide in cucumber. HortScience 16:332-333.
14. Burnham, M., S. C. Phatak, and C. E. Peterson. 1966. Graft-aided inheritance study of a chlorophyll deficient cucumber. Proc. Amer. Soc. Hort. Sci. 89:386-389.
15. Cantliffe, D. J. 1972. Parthenocarpy in cucumber induced by some plant growth regulating chemicals. Can. J. Plant Sci. 52:781-785.
16. Cantliffe, D. J., R. W. Robinson, and R. S. Bastdorff. 1972. Parthenocarpy in cucumber induced by tri-iodobenzoic acid. HortScience 7:285-286.
17. Carlsson, G. 1961. Studies of blind top shoot and its effect on the yield of greenhouse cucumbers. Acta Agr. Scand. 11:160-162.
18. Caruth, T. F. 1975. A genetic study of the inheritance of rupturing carpel in fruit of cucumber, Cucumis sativus L. Ph.D. Dis., Texas A&M Univ., College Station.
19. Chambliss, O. L. 1978. Cucumber beetle resistance in the Cucurbitaceae: Inheritance and breeding. HortScience 13:366 (Abstract).
20. Chono, M., T. Yamauchi, S. Yamaguchi, H. Yamane, and N. Murofushi. 1996. cDNA cloning and characterization of a gibberellin-responsive gene in hypocotyls of Cucumis sativus L. Plant & Cell Physiol. 37:686-691.
21. Chono, M., K. Nemoto, H. Yamane, I. Yamaguchi, and N. Murofushi. 1998. Characterization of a protein kinase gene responsive to auxin and gibberellin in cucumber hypocotyls. Plant & Cell Physiol. 39:958-967.
22. Cochran, F. D. 1938. Breeding cucumbers for resistance to downy mildew. Proc. Amer. Soc. Hort. Sci. 35:541-543.
23. Cohen, S., E. Gertman, and N. Kedar. 1971. Inheritance of resistance to melon mosaic virus in cucumbers. Phytopathology 61:253-255.
24. Cowen, N. M. and D. B. Helsel. 1983. Inheritance of 2 genes for spine color and linkages in a cucumber cross. J. Hered. 74:308-310.
25. Currence. T. M. 1954. Vegetable crops breeding. Teaching manual, Univ. Minn., St. Paul (Mimeo).
26. Da Costa, C. P. and C. M. Jones. 1971a. Cucumber beetle resistance and mite susceptibility controlled by the bitter gene in Cucumis sativus L. Science 172:1145-1146.
27. Da Costa, C. P. and C. M. Jones. 1971b. Resistance in cucumber, Cucumis sativus L., to three species of cucumber beetles. HortScience 6:340-342.
28. Della Vecchia, P. T., C. E. Peterson, and J. E. Staub. 1982. Inheritance of short-day response to flowering in crosses between a Cucumis sativus var. hardwickii (R. ) Alef. line and Cucumis sativus L. lines. Cucurbit Genet. Coop. Rpt. 5:4.
29. Delorme, V. G. R., P. F. Mcabe, D. J. Kim, and C. J. Leaver. 2000. A matrix metalloproteinase gene is expressed at the boundary of senescence and programmed cell death in cucumber. Plant Physiol. 123:917-927.
30. Denna, D. W. 1971. Expression of determinate habit in cucumbers. J. Amer. Soc. Hort. Sci. 96:277-279.
31. den Nijs, A. P. M. and I. W. Boukema. 1983. Results of linkage studies and the need for a cooperative effort to map the cucumber genome. Cucurbit Genet. Coop. Rpt. 6:22-23.
32. den Nijs, A. P. M. and I. W. Boukema. 1985. Short petiole, a useful seedling marker for genetic studies in cucumber. Cucurbit Genet. Coop. Rpt. 8:7-8.
33. den Nijs, A. P. M. and O. M. B. de Ponti. 1983. Umbrella leaf: a gene for sensitivity to low humidity in cucumber. Cucurbit Genet. Coop. Rpt. 6:24.
34. den Nijs, A. P. M. and H. O. Mackiewicz. 1980. "Divided leaf", a recessive seedling marker in cucumber. Cucurbit Genet. Coop. Rpt. 3:24.
35. de Ponti, O. M. and F. Garretsen. 1976. Inheritance of parthenocarpy in pickling cucumbers (Cucumis sativus L. ) and linkage with other characters. Euphytica 25:633­642.
36. de Ruiter, A. C., B. J. van der Knapp, and R. W. Robinson. 1980. Rosette, a spontaneous cucumber mutant arising from cucumber-muskmelon pollen. Cucurbit Genet. Coop. Rpt. 3:4.
37. Dessert, J. M., L. R. Baker, and J. F. Fobes. 1982. Inheritance of reaction to Pseudomonas lachrymans in pickling cucumber. Euphytica 31:847-856.
38. Doruchowski, R. W. and E. Lakowska-Ryk. 1992. Inheritance of resistance to downy mildew (Pseudoperonospora cubensis Berk & Curt) in Cucumis sativus. Proc. 5th EUCARPIA Cucurbitaceae Symp. p. 66-69, Warsaw, Poland.
39. Fanourakis, N. E. 1984. Inheritance and linkage studies of the fruit epidermis structure and investigation of linkage relations of several traits and of meiosis in cucumber. Ph.D. Diss., Univ. of Wisconsin, Madison.
40. Fanourakis, N. E. and P. W. Simon. 1987. Analysis of genetic linkage in the cucumber. J. Hered. 78:238-242.
41. Fanourakis, N. E. and P. W. Simon. 1987. Inheritance and linkage studies of the fruit epidermis structure in cucumber. J. Hered. 78:369-371.
42. Filipecki, M. K., H. Sommer, and S. Malepszy. 1997. The MADS-box gene CUS1 is expressed during cucumber somatic embryogenesis. Plant Sci. 125:63-74.
43. Fujieda, K. and R. Akiya. 1962. Genetic study of powdery mildew resistance and spine color on fruit in cucumber. J. Jpn. Soc. Hort. Sci. 31:30-32.
44. Fujieda, K., V. Fujita, Y. Gunji, and K. Takahashi. 1982. The inheritance of plural-pistillate flowering in cucumber. J. Jap. Soc. Hort. Sci. 51:172-176.
45. Fujii, N., M. Kamada, S. Yamasaki, and H. Takahashi. 2000. Differential accumulation of Aux/IAA mRNA during seedling development and gravity response in cucumber (Cucumis sativus L. ). Plant Mol. Bio. 42:731-740.
46. Galun, E. 1961. Study of the inheritance of sex expression in the cucumber. The interaction of major genes with modifying genetic and non-genetic factors. Genetica 32:134-163.
47. Ganal, M., I. Riede, And V. Hemleben. 1986. Organization and sequence analysis of two related satellite DNAs in cucumber (Cucumis sativus L. ). J. Mol. Evol. 23:23­30.
48. Ganal, M. and V. Hemleben. 1988a. Insertion and amplification of a DNA sequence in satellite DNA of Cucumis sativus (cucumber). Theor. Appl. Genet. 75:357-361.
49. Ganal, M., R. Torres, and V. Hemleben. 1998b. Complex structure of the ribosomal DNA spacer of Cucumis sativus (cucumber). Mol. General Genet. 212:548-554.
50. George, W. L., Jr. 1970. Genetic and environmental modification of determinant plant habit in cucumbers. J. Amer. Soc. Hort. Sci. 95:583-586.
51. Goode, M. J., J. L. Bowers, and A. Bassi, Jr. 1980. Little-leaf, a new kind of pickling cucumber plant. Ark. Farm Res. 29:4.
52. Gornitskaya, I. P. 1967. A spontaneous mutant of cucumber variety Nezhinskii 12. Genetika 3(11):169.
53. Gottlieb, T. D. 1977. Evidence for duplication and divergence of the structural gene for phosphoglucoseisomerase in diploid species of Clarkia. Genetics 86:289­307.
54. Graham, I. A., L. M. Smith, J. W. Brown, C. J. Leaver, and S. M. Smith. 1989. The malate synthase gene of cucumber. Plant Mol. Bio. 13:673-684.
55. Graham, I. A., L. M. Smith, C. J. Leaver, and S. M. Smith. 1990. Developmental regulation of expression of the malate synthase gene in transgenic plants. Plant Mol. Bio. 15:539-549.
56. Greenler, J. M., J. S. Sloan, B. W. Schwartz, and W. M. Becker. 1989. Isolation, characterization and sequence analysis of a full-length cDNA clone encoding NADH-dependent hydroxypyruvate reductase from cucumber. Plant Mol. Bio. 13: 139-150.
57. Greenland, A. J., M. V. Thomas, and R. W. Walde. 1987. Expression of two nuclear genes encoding chloroplast proteins during early development of cucumber seedlings. Planta 170:99-110.
58. Grimbly, P. E. 1980. An apetalous male sterile mutant in cucumber. Cucurbit Genet. Coop. Rpt. 3:9.
59. Groff, D. and M. L. Odland. 1963. Inheritance of closed-flower in the cucumber. J. Hered. 54:191-192.
60. Hande, S. and C. Jayabaskaran. 1997. Nucleotide sequence of a cucumber chloroplast protein tRNA. J. Biosci. 22:143­147.
61. Hande, S. and C. Jayabaskaran. 1996. Cucumber chloroplast trnL(CAA) gene: nucleotide sequence and in vivo expression analysis in etiolated cucumber seedlings treated with benzyladenine and light. Indian J. Biochem. Biophys. 33:448-454.
62. Havey, M. J., Y. H. Park, and G. Bartoszewski. 2004. The Psm locus controls paternal sorting of the cucumber mitochondrial genome. J. Hered. 95:492­497.
63. Hšhne, M., A. Nellen, K. Schwennesen, and H. Kindl. 1996. Lipid body lipoxygenase characterized by protein fragmentation, cDNA sequence and very early expression of the enzyme during germination of cucumber seeds. Eur. J. Biochem. 241:6-11.
64. Hutchins, A. E. 1935. The inheritance of a green flowered variation in Cucumis sativus. Proc. Amer. Soc. Hort. Sci. 33:513.
65. Hutchins, A. E. 1940. Inheritance in the cucumber. J. Agr. Res. 60:117-128.
66. Iezzoni, A. F. and C. E. Peterson. 1979. Linkage of bacterial wilt resistance and sex expression genes in cucumber. Cucurbit Genet. Coop. Rpt. 2:8.
67. Iezzoni, A. F. and C. E. Peterson. 1980. Linkage of bacterial wilt resistance and sex expression in cucumber. HortScience 15:257-258.
68. Iezzoni, A. F., C. E. Peterson, and G. E. Tolla. 1982. Genetic analysis of two perfect flowered mutants in cucumber. J. Amer. Soc. Hort. Sci. 107:678-681.
69. Iida, S. and E. Amano. 1990. Pollen irradiation to obtain mutants in monoecious cucumber. Gamma Field Symp. 29:95-111.
70. Iida, S. and E. Amano. 1991. Mutants induced by pollen irradiation in cucumber. Cucurbit Genet. Coop. Rpt. 14:32-33.
71. Inggamer, H. and O. M. B. de Ponti. 1980. The identity of genes for glabrousness in Cucumis sativus L. Cucurbit Genet. Coop. Rpt. 3:14.
72. Iwasaki, Y., M. Komano, and T. Takabe. 1995. Molecular cloning of cDNA for a 17.5-kDa polypeptide, the psaL gene product, associated with cucumber Photosystem I. Biosci. Biotechnol. Biochem. 59:1758-1760.
73. Jayabaskaran, C. and M. Puttaraju. 1993. Fractionation and identification of cytoplasmic tRNAs and structural characterization of a phenylalanine and a leucine tRNA from cucumber hypocotyls. Biochem. Mol. Biol. Int. 31:983-995.
74. Jenkins, J. M., Jr. 1946. Studies on the inheritance of downy mildew resistance. J. Hered. 37:267-276.
75. John, C. A. and J. D. Wilson. 1952. A "ginko leafed" mutation in the cucumber. J. Hered. 43:47-48.
76. Jones, R. W. 1984. Studies related to genetic salt tolerance in the cucumber, Cucumis sativus L. Ph.D. Diss., Texas A&M Univ., College Station.
77. Kabelka, E. and R. Grumet. 1997. Inheritance of resistance to the Moroccan watermelon mosaic virus in the cucumber line TMG-1 and cosegregation with zucchini yellow mosaic virus resistance. Euphytica 95:237-242.
78. Kabelka, E., Z. Ullah and R. Grumet. 1997. Multiple alleles for zucchini yellow mosaic virus resistance at the zym locus in cucumber. Theor. Appl. Genet. 95:997­1004.
79. Kamada, M., N. Fujii, S. Aizawa, S. Kamigaichi, C. Mukai, T. Shimazu, and H. Takahashi. 2000. Control of gravimorphogenesis by auxin: accumulation pattern of CS-IAA1 mRNA in cucumber seedlings grown in space and on the ground. Planta 211:493-501.
80. Kamachi, S., H. Sekimoto, N. Kondo, and S. Sakai. 1997. Cloning of a cDNA for a 1­aminocyclopropane-1-carboxylate synthase that is expressed during development of female flowers at the apices of Cucumis sativus L. Plant Cell Physiol. 38:1197-1206.
81. Kater, M. M., L. Colombo, J. Franken, M. Busscher, S. Masiero, M. M. Van-Lookeren-Campagne, and G. C. Angenent. 1998. Multiple AGAMOUS homologs from cucumber and petunia differ in their ability to induce reproductive organ fate. Plant Cell 10:171-182.
82. Kauffman, C. S. and R. L. Lower. 1976. Inheritance of an extreme dwarf plant type in the cucumber. J. Amer. Soc. Hort. Sci. 101:150-151.
83. Kennard, W. C., K. Poetter, A. Dijkhuizen, V. Meglic, J. E. Staub, and M. J. Havey. 1994. Linkages among RFLP, RAPD, isozyme, disease-resistance, and morphological markers in narrow and wide crosses of cucumber. Theor. Appl. Genet. 89:42-48.
84. Kim, D. J. and S. M. Smith. 1994a. Molecular cloning of cucumber phosphoenolpyruvate carboxykinase and developmental regulation of gene expression. Plant Mol. Biol. 26:423-434.
85. Kim, D. J. and S. M. Smith. 1994b. Expression of a single gene encoding microbody NAD-malate dehydrogenase during glyoxysome and peroxisome development in cucumber. Plant Mol. Biol. 26:1833-1841.
86. Kim, D. J., S. M. Smith, and C. J. Leaver. 1997. A cDNA encoding a putative SPF1­type DNA-binding protein from cucumber. Gene 185:265-269.
87. Knerr, L. D. and J. E. Staub. 1992. Inheritance and linkage relationships of isozyme loci in cucumber (Cucumis sativus L. ). Theor. Appl. Genet. 84:217-224.
88. Knerr, L. D., V. Meglic and J. E. Staub. 1995. A fourth malate dehydrogenase (MDH) locus in cucumber. HortScience 30:118-119.
89. Kooistra, E. 1968. Powdery mildew resistance in cucumber. Euphytica 17:236­244.
90. Kooistra, E. 1971. Inheritance of flesh and skin colors in powdery mildew resistant cucumbers (Cucumis sativus L. ). Euphytica 20:521-523.
91. Kubicki, B. 1965. New possibilities of applying different sex types in cucumber breeding. Genetica Polonica 6:241-250.
92. Kubicki, B. 1969a. Investigations of sex determination in cucumber (Cucumis sativus L. ). IV. Multiple alleles of locus Acr. Genetica Polonica 10:23-68.
93. Kubicki, B. 1969b. Investigations of sex determination in cucumber (Cucumis sativus L. ). V. Genes controlling intensity of femaleness. Genetica Polonica 10:69-86.
94. Kubicki, B. 1969c. Investigations on sex determination in cucumbers (Cucumis sativus L.). VI. Androecism. Genetica Polonica 10:87-99.
95. Kubicki, B. 1969d. Investigations of sex determination in cucumber (Cucumis sativus L.). VII. Trimonoecism. Genetica Polonica 10:123-143.
96. Kubicki, B. 1974. New sex types in cucumber and their uses in breeding work. Proc. XIX Intl. Hort. Congr. 3:475-485.
97. Kubicki, B. and A. Korzeniewska. 1983. Inheritance of the presence of empty chambers in fruit as related to the other fruit characters in cucumbers (Cucumis sativus L.). Genetica Polonica 24:327-342.
98. Kubicki, B. and A. Korzeniewska. 1984. Induced mutations in cucumber (Cucumis sativus L.) III. A mutant with choripetalous flowers. Genetica Polonica 25:53-60.
99. Kubicki, B., I. Goszczycka, and A. Korzeniewska. 1984. Induced mutations in cucumber (Cucumis sativus L.) II. Mutant of gigantism. Genetica Polonica 25:41-52.
100. Kubicki, B., U. Soltysiak, and A. Korzeniewska. 1986a. Induced mutations in cucumber (Cucumis sativus L.) IV. A mutant of the bush type of growth. Genetica Polonica 27:273-287.
101. Kubicki, B., U. Soltysiak, and A. Korzeniewska. 1986b. Induced mutations in cucumber (Cucumis sativus L.) V. Compact type of growth. Genetica Polonica 27:289-298.
102. Kubo, Y., Y.B. Xue, A. Nakatsuka, F.M. Mathooko, A. Inaba, and R. Nakamura. 2000. Expression of a water stress-induced polygalacturonase gene in harvested cucumber fruit. J. Japan. Soc. Hort. Sci. 69:273-279.
103. Kuroda, H., T. Masuda, H. Ohta, Y. Shioi, and K. Takamiya. 1995. Light-enhanced gene expression of NADPH­protochlorophyllide oxidoreductase in cucumber. Biochem. Biophys. Res. Commun. 210:310-316.
104. Lane, K. P. and H. M. Munger. 1985. Linkage between Corynespora leafspot resistance and powdery mildew susceptibility in cucumber (Cucumis sativus). HortScience 20(3):593 (Abstract).
105. Lawton, K. A., J. Beck, S. Potter, E. Ward, and J. Ryals. 1994. Regulation of cucumber class III chitinase gene expression. Mol. Plant Microbe. Interact. 7:48-57.
106. Lower, R. A., J. Nienhuis, and C. H. Miller. 1982. Gene action and heterosis for yield and vegetative characteristics in a cross between a gynoecious pickling cucumber and a Cucumis sativus var. hardwickii line. J. Amer. Soc. Hort. Sci. 107:75-78.
107. Masuda, S., C. Sakuta, and S. Satoh. 1999. CDNA cloning of a novel lectin-like xylem sap protein and its root-specific expression in cucumber. Plant Cell Physiol. 40:1177­1181.
108. Mathooko, F. M., M. W. Mwaniki, A. Nakatsuka, S. Shiomi, Y. Kubo, A. Inaba, and R. Nakamura. 1999. Expression characteristics of CS-ACS1, CS-ACS2 and CS-ACS3, three members of the 1­aminocyclopropane-1-carboxylate synthase gene family in cucumber (Cucumis sativus L.) fruit under carbon dioxide stress. Plant Cell Physiol. 40:164-172.
109. Matsui, K., M. Nishioka, M. Ikeyoshi, Y. Matsumura, T. Mori, and T. Kajiwara. 1998. Cucumber root lipoxygenase can act on acyl groups in phosphatidylcholine. Biochim. Biophys. Acta 1390:8-20.
110. Matsui, K., K. Hijiya, Y. Tabuchi, and T. Kajiwara. 1999. Cucumber cotyledon lipoxygenase during postgerminative growth. Its expression and action on lipid bodies. Plant Physiol. 119:1279-1287.
111. May, C., R. Preisig-Muller, M. Hohne, P. Gnau, and H. Kindl, 1998. A phospholipase A2 is transiently synthesized during seed germination and localized to lipid bodies. Biochim. Biophys. Acta 1393:267-276.
112. Metraux, J. P., W. Burkhart, M. Moyer, S. Dincher, and W. Middlesteadt. 1989. Isolation of a complementary DNA encoding a chitinase with structural homology to a bifunctional lysozyme/chitinase. Proc. Natl. Acad. Sci. USA 86:896-900.
113. Meglic, V. and J. E. Staub. 1996. Inheritance and linkage relationships of isozyme and morphological loci in cucumber (Cucumis sativus L.). Theor. Appl. Genet. 92:865-872.
114. Miller, G. A. and W. L. George, Jr. 1979. Inheritance of dwarf determinate growth habits in cucumber. J. Amer. Soc. Hort. Sci. 104:114-117.
115. Miller, J. C., Jr. and J. E. Quisenberry. 1978. Inheritance of flower bud abortion in cucumber. HortScience 13:44-45.
116. Miyamoto, K., R. Tanaka, H. Teramoto, T. Masuda, H. Tsuji, and H. Inokuchi. 1994. Nucleotide sequences of cDNA clones encoding ferrochelatase from barley and cucumber. Plant Physiol. 105:769-770.
117. Morgens, P. H., A. M. Callahan, L. J. Dunn, and F. B. Abeles. 1990. Isolation and sequencing of cDNA clones encoding ethylene-induced putative peroxidases from cucumber cotyledons. Plant Mol. Biol. 14: 715-725.
118. Munger, H. M. and D. P. Lane. 1987. Source of combined resistance to powdery mildew and Corynespora leafspot in cucumber. Cucurbit Genet. Coop. Rpt. 10:1.
119. Munger, H. M. and R. E. Wilkinson.  1975. Scab resistance in relation to fruit length in slicing cucumbers. Veg. Imp. Nwsl. 17:2.
120. Nandgaonkar, A. K. and L. R. Baker. 1981. Inheritance of multi-pistillate flowering habit in gynoecious pickling cucumber. J. Amer. Soc. Hort. Sci. 106:755-757.
121. Nersissian, A. M., Z. B. Mehrabian, R. M. Nalbandyan, P. J. Hart, G. Fraczkiewicz, R. S. Czernuszewicz, C. J. Bender, J. Peisach, R. G. Herrmann, and J. S. Valentine. 1996. Cloning, expression, and spectroscopic characterization of Cucumis sativus stellacyanin in its nonglycosylated form. Protein Sci. 5:2184-2192.
122. Netzer, D., S. Niegro, and F. Galun. 1977. A dominant gene conferring resistance to Fusarium wilt in cucumber. Phytopathology 67:525-527.
123. Nuttall, W. W. and J. J. Jasmin.  1958. The inheritance of resistance to bacterial wilt (Erwinia tracheiphila [E. F. Sm.] Holland) in cucumber. Can. J. Plant Sci. 38:401-404.
124. Odland, M. L. and D. W. Groff. 1963a. Inheritance of crinkled-leaf cucumber. Proc. Amer. Soc. Hort. Sci. 83:536-537.
125. Odland, M. L. and D. W. Groff. 1963b. Linkage of vine type and geotropic response with sex forms in cucumber Cucumis sativus L. Proc. Amer. Soc. Hort. Sci. 82:358-369.
126. Ohkawa, J., N. Okada, A. Shinmyo, and M. Takano. 1989. Primary structure of cucumber (Cucumis sativus) ascorbate oxidase deduced from cDNA sequence: homology with blue copper proteins and tissue-specific expression. Proc. Natl. Acad. Sci. USA 86:1239-1243.
127. Ohkawa, J., A. Shinmyo, M. Kanchanapoon, N. Okada, and M. Takano. 1990. Structure and expression of the gene coding for a multicopper enzyme, ascorbate oxidase of cucumber. Ann. N Y Acad. Sci. 613:483­488.
128. Ovadis, M., M. Vishnevetsky, and A. Vainstein. 1998. Isolation and sequence analysis of a gene from Cucumis sativus encoding the carotenoid-associated protein CHRC. Plant Physiol. 118:1536.
129. Owens, K. W. and C. E. Peterson. 1982. Linkage of sex type, growth habit and fruit length in 2 cucumber inbred backcross populations. Cucurbit Genet. Coop. Rpt. 5:12.
130. Perl-Treves, R., A. Kahana, N. Rosenman, Y. Xiang, and L. Silberstein. 1998. Expression of multiple AGAMOUS-like genes in male and female flowers of cucumber (Cucumis sativus L.). Plant Cell Physiol. 39:701-710.
131. Peterson, G. C. and L. M. Pike. 1992. Inheritance of green mature seed-stage fruit color in Cucumis sativus L. J. Amer. Soc. Hort. Sci. 117:643-645.
132. Pierce, L. K. and T. C. Wehner. 1989. Gene list for cucumber. Cucurbit Genet. Coop. Rpt. 12:91-103.
133. Pierce, L. K. and T. C. Wehner. 1990. Review of genes and linkage groups in cucumber. HortScience 25:605-615.
134. Pike L. M. and T. F. Caruth. 1977. A genetic study of the inheritance of rupturing carpel in fruit of cucumber, Cucumis sativus L. HortScience 12:235 (Abstract).
135. Pike, L. M. and C. E. Peterson. 1969. Inheritance of parthenocarpy in the cucumber (Cucumis sativus L.). Euphytica 18:101-105.
136. Poole, C. F. 1944. Genetics of cultivated cucurbits. J. Hered. 35:122-128.
137. Preisig-Müller, R. and H. Kindl. 1992. Sequence analysis of cucumber cotyledon ribulosebisphosphate carboxylase/oxygenase activase cDNA. Biochim. Biophys. Acta 1171:205-206.
138. Preisig-Müller, R. and H. Kindl. 1993a. Thiolase mRNA translated in vitro yields a peptide with a putative N-terminal presequence. Plant Mol. Biol. 22:59-66.
139. Preisig-Müller, R. and H. Kindl. 1993b. Plant dnaJ homologue: molecular cloning, bacterial expression, and expression analysis in tissues of cucumber seedlings. Arch. Biochem. Biophys. 305:30-37.
140. Preisig-Müller, R., K. Guhnemann-Schafer, and H. Kindl. 1994. Domains of the tetrafunctional protein acting in glyoxysomal fatty acid beta-oxidation. Demonstration of epimerase and isomerase activities on a peptide lacking hydratase activity. J. Biol. Chem. 269:20475-20481.
141. Provvidenti, R. 1985. Sources of resistance to viruses in two accessions of Cucumis sativus. Cucurbit Genet. Coop. Rpt. 8:12.
142. Provvidenti, R. 1987. Inheritance of resistance to a strain of zucchini yellow mosaic virus in cucumber. HortScience 22:102-103.
143. Pyzenkov, V. I. and G. A. Kosareva. 1981. A spontaneous mutant of the dwarf type. Bul. Applied Bot. Plant Breeding 69:15-21.
144. Pyzhenkov, V. I. and G. A. Kosareva. 1981. Description of features and their inheritance pattern in a new cucumber mutant. Biull. Vses. Inst. Rastenievod 109:5-8 (Plant Breeding Abstracts 1983, 53:478).
145. Reynolds S. J. and S. M. Smith. 1995. The isocitrate lyase gene of cucumber: isolation, characterisation and expression in cotyledons following seed germination. Plant Mol. Biol. 27:487-497.
146. Richmond, R. C.  1972. Enzyme variability in the Drosophila williston group. 3. Amounts of variability in the super species D. paulistorum. Genetics 70:87-112.
147. Robinson, R. W. 1978a. Association of fruit and sex expression in the cucumber. Cucurbit Genet. Coop. Rpt. 1:10.
148. Robinson, R. W. 1978b. Fasciation in the cucumber. Cucurbit Genet. Coop. Rpt. 1:11a.
149. Robinson, R. W. 1978c. Gene linkage in 'Lemon' cucumber. Cucurbit Genet. Coop. Rpt. 1:12.
150. Robinson, R. W. 1978d. Linkage of male sterility and sex expression genes in cucumber. Cucurbit Genet. Coop. Rpt. 1:13.
151. Robinson, R. W. 1978e. Linkage relations of genes for tolerance to powdery mildew in cucumber. Cucurbit Genet. Coop. Rpt. 1:11b.
152. Robinson, R. W. 1978f. Pleiotropic effects of the glabrous gene of the cucumber. Cucurbit Genet. Coop. Rpt. 1:14.
153. Robinson, R. W. 1979. New genes for the Cucurbitaceae. Cucurbit Genet. Coop. Rpt. 2:49-53.
154. Robinson, R. W. 1987a. Blunt leaf apex, a cucumber mutant induced by a chemical mutagen. Cucurbit Genet. Coop. Rpt. 10:6.
155. Robinson, R. W. 1987b. Chlorosis induced in glabrous cucumber by high temperature. Cucurbit Genet. Coop. Rpt. 10:7.
156. Robinson, R. W. 1987c. Cordate, a leaf shape gene with pleiotropic effects on flower structure and insect pollination. Cucurbit Genet. Coop. Rpt. 10:8.
157. Robinson, R. W. 1987d. Independence of gl and yc. Cucurbit Genet. Coop. Rpt. 10:11.
158. Robinson, R. W. 1987e. Inheritance of opposite leaf arrangement in Cucumis sativus L. Cucurbit Genet. Coop. Rpt. 10:10.
159. Robinson, R. W. and W. Mishanec. 1964. A radiation-induced seedling marker gene for cucumbers. Veg. Imp. Nwsl. 6:2.
160. Robinson, R. W. and W. Mishanec. 1965. A new dwarf cucumber. Veg. Imp. Nwsl. 7:23.
161. Robinson, R. W. and W. Mishanec. 1967. Male sterility in the cucumber. Veg. Imp. Nwsl. 9:2.
162. Robinson, R. W., H. M. Munger, T. W. Whitaker, and G. W. Bohn.  1976. Genes of the Cucurbitaceae. HortScience 11:554-568.
163. Robinson, R. W. and J. W. Shail.  1981. A cucumber mutant with increased hypocotyl and internode length. Cucurbit Genet. Coop. Rpt. 4:19-20.
164. Robinson, R. W., T. C. Wehner, J. D. McCreight, W. R. Henderson, and C. A, John. 1982. Update of the cucurbit gene list and nomenclature rules. Cucurbit Genet. Coop. Rpt. 5:62-66.
165. Robinson, R. W. and T. W. Whitaker.  1974. Cucumis, p. 145-150. In: R. C. King (ed), Handbook of Genetics. vol. 2. Plenum, New York.
166. Rosa, J. T. 1928. The inheritance of flower types in Cucumis and Citrullus. Hilgardia 3:233-250.
167. Rowe, J. T. and J. L. Bowers. 1965. The inheritance and potential of an irradiation induced tendrilless character in cucumbers. Proc. Amer. Soc. Hort. Sci. 86:436-441.
168. Rucinska, M., K. Niemirowicz-Szczytt, and A. Korzeniewska. 1991. A cucumber (Cucumis sativus L.) mutant with yellow stem and leaf petioles. Cucurbit Genet. Coop. Rpt. 14:8-9.
169. Rucinska, M., K. Niemirowicz-Szczytt, and A. Korzeniewska. 1992a. Cucumber (Cucumis sativus L.) induced mutations. II. A second short petiole mutant. Cucurbit Genet. Coop. Rpt. 15:33-34.
170. Rucinska, M., K. Niemirowicz-Szczytt, and A. Korzeniewska. 1992b. Cucumber (Cucumis sativus L.) induced mutations. III and IV. Divided and gingko leaves. Proc. 5th EUCARPIA Cucurbitaceae Symp. p. 66­69, Warsaw, Poland.
171. Sakuta, C., A. Oda, S. Yamakawa, and S. Satoh. 1998. Root-specific expression of genes for novel glycine-rich proteins cloned by use of an antiserum against xylem sap proteins of cucumber. Plant Cell Physiol. 39:1330-1336.
172. Sano, S. and K. Asada. 1994. cDNA cloning of monodehydroascorbate radical reductase from cucumber: a high degree of homology in terms of amino acid sequence between this enzyme and bacterial flavoenzymes. Plant Cell Physiol. 35:425-437.
173. Schwartz, B. W., Sloan, J. S. and Becker, W. M. (1991). Characterization of genes encoding hydroxypyruvate reductase in cucumber. Plant Molecular Biology, 17, 941-947.
174. Shanklin, J. and Somerville, C. (1991). Stearoyl-acyl-carrier-protein desaturase from higher plants is structurally unrelated to the animal and fungal homologs. Proceedings of the National Academy of Sciences of the United States of America, 88, 2510-2514.
175. Shanmugasundarum, S. and P. H. Williams. 1971. A Cotyledon marker gene in cucumbers. Veg. Imp. Nwsl. 13:4.
176. Shanmugasundarum, S., P. H. Williams, and C. E. Peterson.  1971. A recessive cotyledon marker gene in cucumber with pleiotropic effects. HortScience 7:555-556.
177. Shanmugasundarum, S., P. H. Williams, and C. E. Peterson. 1971a. Inheritance of fruit spine color in cucumber. HortScience 6:213-214.
178. Shanmugasundarum, S., P. H. Williams, and C. E. Peterson. 1971b. Inheritance of resistance to powdery mildew in cucumber. Phytopathology 61:1218-1221.
179. Shanmugasundarum, S., P. H. Williams, and C. E. Peterson.  1972. A recessive cotyledon marker gene in cucumber with pleiotropic effects. HortScience 7:555-556.
180. Shcherban, T. Y., J. Shi, D. M. Durachko, M. J. Guiltinan, S. J. McQueen-Mason, M. Shieh, and D. J. Cosgrove. 1995. Molecular cloning and sequence analysis of expansins­-a highly conserved, multigene family of proteins that mediate cell wall extension in plants. Proc. Natl. Acad. Sci. USA 92:9245­9249.
181. Shifriss, O. 1950. Spontaneous mutations in the American varieties of Cucumis sativus L. Proc. Amer. Soc. Hort. Sci. 55:351-357.
182. Shifriss, O. 1961. Sex control in cucumbers. J. Hered. 52:5-12.
183. Shifriss, O. and W. L. George, Jr.  1965. Delayed germination and flowering in cucumbers. Nature (London) 506:424-425.
184. Shifriss, O., C. H. Myers, and C. Chupp. 1942. Resistance to mosaic virus in cucumber. Phytopathology 32:773-784.
185. Shimizu, S., K. Kanazawa, and A. Kato. 1963. Studies on the breeding of cucumber for resistance to downy mildew. Part 2. Difference of resistance to downy mildew among the cucumber varieties and the utility of the cucumber variety resistance to downy mildew (in Japanese). Bul. Hort. Res. Sta. Jpn. Ser. A, No. 2:80-81.
186. Shimojima, M., H. Ohta, A. Iwamatsu, T. Masuda, Y. Shioi, and K. Takamiya. 1997. Cloning of the gene for monogalactosyldiacylglycerol synthase and its evolutionary origin. Proc. Natl. Acad. Sci. USA 94:333-337.
187. Shiomi, S., M. Yamamoto, T. Ono, K. Kakiuchi, J. Nakamoto, A. Makatsuka, Y. Kudo, R. Nakamura, A. Inaba, and H. Imaseki. 1998. cDNA cloning of ACC synthase and ACC oxidase genes in cucumber fruit and their differential expression by wounding and auxin. J. Japan. Soc. Hort. Sci. 67:685-692.
188. Smith, S. M. and C. J. Leaver. 1986. Glyoxysomal malate synthase of cucumber: molecular cloning of a cDNA and regulation of enzyme synthesis during germination. Plant Physiol. 81:762-767.
189. Soans, A. B., D. Pimentel, and J. S. Soans. 1973. Cucumber resistance to the two-spotted spider mite. J. Econ. Entomol. 66:380-382.
190. Soltysiak, U. and B. Kubicki. 1988. Induced mutations in the cucumber (Cucumis sativus L.). VII. Short hypocotyl mutant. Genetica Polonica 29:315-321.
191. Soltysiak, U., B. Kubicki, and A. Korzeniewska. 1986. Induced mutations in cucumber (Cucumis sativus L.). VI. Determinate type of growth. Genetica Polonica 27:299-308.
192. Staub, J. E., R. S. Kupper, D. Schuman, T. C. Wehner, and B. May. 1985. Electrophoretic variation and enzyme storage stability in cucumber. J. Amer. Soc. Hort. Sci. 110:426-431.
193. Strong, W. J.  1931. Breeding experiments with the cucumber (Cucumis sativus L.). Sci. Agr. 11:333-346.
194. Suyama, T., Yamada, K., Mori, H., Takeno, K. and Yamaki, S. (1999). Cloning cDNAs for genes preferentially expressed during fruit growth in cucumber. Journal of American Society for Horticultural Science, 124, 136-139.
195. Tanaka, R., K. Yoshida, T. Nakayashiki, T. Masuda, H. Tsuji, H. Inokuchi, and A. Tanaka. 1996. Differential expression of two hemA mRNAs encoding glutamyl-tRNA reductase proteins in greening cucumber seedlings. Plant Physiol. 110:1223-1230.
196. Teramoto, H., E. Momotani, G. Takeba, and H. Tsuji. 1994. Isolation of a cDNA clone for a cytokinin-repressed gene in excised cucumber cotyledons. Planta 193:573-579.
197. Teramoto, H., T. Toyama, G. Takeba, and T. Tsuji. 1996. Noncoding RNA for CR20, a cytokinin-repressed gene of cucumber. Plant Mol. Biol. 32:797-808.
198. Tkachenko, N. N. 1935. Preliminary results of a genetic investigation of the cucumber, Cucumis sativus L. Bul. Applied Plant Breeding, Ser. 2, 9:311-356.
199. Thaxton, P. M. 1974. A genetic study of the clustering characteristic of pistillate flowers in the cucumber, Cucumis sativus L. M.S. Thesis, Texas A&M Univ., College Station.
200. Tolla, G. E. and C. E. Peterson. 1979. Comparison of gibberellin A4/A7 and silver nitrate for induction of staminate flowers in a gynoecious cucumber line. HortScience 14:542-544.
201. Toyama, T., H. Teramoto, G. Takeba, and H. Tsuji. 1995. Cytokinin induces a rapid decrease in the levels of mRNAs for catalase, 3-hydroxy-3-methylglutaryl CoA reductase, lectin and other unidentified proteins in etiolated cotyledons of cucumber. Plant Cell Physiol. 36: 1349­1359.
202. Toyama, T., H. Teramoto, and G. Takeba. 1996. The level of mRNA transcribed from psaL, which encodes a subunit of photosystem I, is increased by cytokinin in darkness in etiolated cotyledons of cucumber. Plant Cell Physiol. 37:1038­1041.
203. Toyama, T., H. Teramoto, S. Ishiguro, A. Tanaka, K. Okada and G. Taketa. 1999. A cytokinin-repressed gene in cucumber for a bHLH protein homologue is regulated by light. Plant Cell Physiol. 40:1087-1092.
204. Trebitsh, T., J. E. Staub, and S. D. O'Neill. 1997. Identification of a 1­aminocyclopropane-1-carboxylic acid synthase gene linked to the female (F) locus that enhances female sex expression in cucumber. Plant Physiol. 113: 987-995.
205. Vakalounakis, D. J. 1992. Heart leaf, a recessive leaf shape marker in cucumber: linkage with disease resistance and other traits. J. Heredity 83:217-221.
206. Vakalounakis, D. J. 1993. Inheritance and genetic linkage of fusarium wilt (Fusarium oxysporum f. sp. cucumerinum race 1) and scab (Cladosporium cucumerinum) resistance genes in cucumber (Cucumis sativus). Annals of Applied Biology 123:359-365.
207. Vakalounakis, D. J. 1995. Inheritance and linkage of resistance in cucumber line SMR­18 to races 1 and 2 of Fusarium oxysporum f. sp. cucumerinum. Plant Pathology 44:169-172.
208. Vakalounakis, D. J. 1996. Allelism of the Fcu-1 and Foc genes conferring resistance to fusarium wilt in cucumber. European J. Plant Pathology 102:855-858.
209. van Es, J. 1958. Bladruuresistantie by konkommers. Zaabelangen 12:116-117.
210. van Vliet, G. J. A. and W. D. Meysing. 1974. Inheritance of resistance to Pseudoperonospora cubensis Rost. in cucumber (Cucumis sativus L.). Euphytica 23:251-255.
211. van Vliet, G. J. A. and W. D. Meysing. 1977. Relation in the inheritance of resistance to Pseudoperonospora cubensis Rost. and Sphaerotheca fuliginea Poll. in cucumber (Cucumis sativus L.). Euphytica 26:793-796.
212. Vishnevetsky, M., M. Ovadis, H. Itzhaki, M. Levy, Y. Libal-Weksler, Z. Adam, and A. Vainstein. 1996. Molecular cloning of a carotenoid-associated protein from Cucumis sativus corollas: homologous genes involved in carotenoid sequestration in chromoplasts. Plant J. 10:1111-1118.
213. Wai, T. and R. Grumet.  1995. Inheritance of resistance to the watermelon strain of papaya ringspot virus in the cucumber line TMG-1. HortScience 30:338-340.
214. Wai, T., J. E. Staub, E. Kabelka and R. Grumet. 1997. Linkage analysis of potyvirus resistance alleles in cucumber. J. Heredity. 88: 454-458.
215. Wall, J. R. 1967. Correlated inheritance of sex expression and fruit shape in Cucumis. Euphytica 23:251-255.
216. Walters, S. A., T. C. Wehner, and K. R. Barker. 1996. NC-42 and NC-43: Root-knot nematode-resistant cucumber germplasm. HortScience 31:1246-1247.
217. Walters, S. A., T. C. Wehner, and K. R. Barker. 1997. A single recessive gene for resistance to the root-knot nematode (Meloidogyne javanica) in Cucumis sativus var. hardwickii. J. Heredity 88: 66-69.
218. Walters, S. A. and T. C. Wehner.  1998. Independence of the mj nematode resistance gene from 17 gene loci in cucumber. HortScience 33:1050-1052.
219. Wang, Y. J., R. Provvidenti, and R. W. Robinson. 1984. Inheritance of resistance to watermelon mosaic virus 1 in cucumber. HortScience 19:587-588.
220. Wang, Y. J., R. Provvidenti, and R. W. Robinson. 1984. Inheritance of resistance in cucumber to watermelon mosaic virus. Phytopathology 51:423-428.
221. Wasuwat, S. L. and J. C. Walker. 1961. Inheritance of resistance in cucumber to cucumber mosaic virus. Phytopathology 51:423-428.
222. Wehner, T. C. 1993. Gene list update for cucumber. Cucurbit Genet. Coop. Rpt. 16: 92-97.
223. Wehner, T. C., J. E. Staub, and C. E. Peterson. 1987. Inheritance of littleleaf and multi-branched plant type in cucumber. Cucurbit Genet. Coop. Rpt. 10:33.
224. Wehner, T. C. and Staub, J. E. 1997. Gene list for cucumber. Cucurbit Genetics Cooperative Report, 20:66-88.
225. Wehner, T. C., J. S. Liu, and J. E. Staub. 1998a. Two-gene interaction and linkage for bitterfree foliage in cucumber. J. Amer. Soc. Hort. Sci. 123: 401-403.
226. Wehner, T. C., J. E. Staub, and J. S. Liu. 1998b. A recessive gene for revolute cotyledons in cucumber. J. Hered. 89: 86­ 87.
227. Wellington, R. 1913. Mendelian inheritance of epidermal characters in the fruit of Cucumis sativus. Science 38:61.
228. Wellington, R. and L. R. Hawthorn. 1928. A parthenocarpic hybrid derived from a cross between and English forcing cucumber and the Arlington White Spine. Proc. Amer. Soc. Hort. Sci. 25:97-100.
229. Whelan, E. D. P. 1971. Golden cotyledon: a radiation-induced mutant in cucumber. HortScience 6:343 (abstract).
230. Whelan, E. D. P. 1972a. A cytogenetic study of a radiation-induced male sterile mutant of cucumber. J. Amer. Soc. Hort. Sci. 97:506-509.
231. Whelan, E. D. P. 1972b. Inheritance of a radiation-induced light sensitive mutant of cucumber. J. Amer. Soc. Hort. Sci. 97:765­767.
232. Whelan, E. D. P. 1973. Inheritance and linkage relationship of two radiation-induced seedling mutants of cucumber. Can. J. Genet. Cytol. 15:597-603.
233. Whelan, E. D. P. 1974. Linkage of male sterility, glabrate and determinate plant habit in cucumber. HortScience 9:576-577.
234. Whelan, E. D. P. and B. B. Chubey. 1973. Chlorophyll content of new cotyledon mutants of cucumber. HortScience 10:267­269.
235. Whelan, E. D. P., P. H. Williams, and A. Abul-Hayja. 1975. The inheritance of two induced cotyledon mutants of cucumber. HortScience 10:267-269.
236. Wilson, J. M. 1968. The relationship between scab resistance and fruit length in cucumber, Cucumis sativus L. M.S. Thesis, Cornell Univ., Ithaca, NY.
237. Winnik, A. G. and L. F. Vetusnjak.  1952. Intervarietal hybridization of cucumber. Agrobiologia 4:125-131.
238. Xie, J. and T. C. Wehner.  2001. Gene list 2001 for cucumber. Cucurbit Genet. Coop. Rpt. 24: 110-136.
239. Yamasaki, S., N. Fujii, and H. Takahashi. 2000. The ethylene-regulated expression of CS-ETR2 and CS-ERS genes in cucumber plants and their possible involvement with sex expression in flowers. Plant Cell Physiol. 41:608-616.
240. Youngner, V. B. 1952. A study of the inheritance of several characters in the cucumber. Ph.D. Diss. Univ. of Minnesota, St. Paul.
241. Zhang, Q., A. C. Gabert, and J. R. Baggett. 1994. Characterizing a cucumber pollen sterile mutant: inheritance, allelism, and response to chemical and environmental factors. J. Amer. Soc. Hort. Sci. 119:804­807.
242. Zentgraf, U., M. Ganal, and V. Hemleben. 1990. Length heterogeneity of the rRNA precursor in cucumber (Cucumis sativus). Plant Mol. Bio. 15:465-474.
243. Zijlstra, S.  1987. Further linkage studies in Cucumis sativus L. Cucurbit Genet. Coop. Rpt. 10:39.
244. Zijlstra, S. and A. P. M. den Nijs.  1986. Further results of linkage studies in Cucumis sativus L. Cucurbit Genet. Coop. Rpt. 9:55.