ARS | Publication request: An Extended Intervarietal Microsatellite Linkage Map of Cucumber, Cucumis Sativus L

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 25, 2010
Publication Date: June 20, 2010
Citation: Weng, Y., Staub, J.E., Johnson, S., Huang, S. 2010. An Extended Intervarietal Microsatellite Linkage Map of Cucumber, Cucumis Sativus L. HortScience. 45:882-886.

Interpretive Summary: A recombinant inbred line (RIL) population derived from two cultivated cucumber lines Gy-7 and H-19 was previously utilized to map yield and fruit quality components. However, that map consisted mainly of dominant markers that are not suitable in plant improvement and gene cloning. We report herein a moderately saturated genetic map derived from this RIL population that incorporates codominant microsatellite (SSR) markers and two architectural traits, little leaf (ll) and determinate (de) growth habit. Of 821 cucumber SSR markers evaluated for map construction, 17.0% (140) were polymorphic between the two parental lines. In combination with 42 previously makers, these polymorphic markers were employed to construct a 176-point linkage map spanning ~ 400 cM across seven linkage groups (LG). The little leaf gene (ll) was flanked by two markers SSR02355 and SSR03940 that were 4.2 and 3.6 cM from ll, respectively. The de gene for determinate growth habit was flanked by markers CSWCTT14b and SSR13251 (1.4 and 4.2 cM from the de, respectively). The SSR markers linked with the de and ll genes were mapped to cucumber Chromosome 6, and no recombination suppression was detected among the mapped loci examined. This Gy-7 × H-19 RIL-based genetic map shared 94 markers in common with a previously reported linkage map derived from a wide cross between cultivated cucumber line Gy-14 and wild cucumber line PI 183967. Comparison of marker order between the two maps supported previous findings of possible chromosomal rearrangements exist between Gy-14 and PI 183967. The molecular markers identified from the present study are valuable for marker-assisted selction of architectural genes for little leaf and determinate growth habit in cucumber breeding.

Technical Abstract: A recombinant inbred line (RIL) population derived from two cultivated cucumber (Cucumis sativus var. sativus L., 2n = 2x = 14) lines Gy-7 (synom. G421) and H-19 was previously utilized to map yield and fruit quality components. However, that map consisted mainly of dominant markers (i.e., AFLPs and RAPDs) limiting its utility in plant improvement and map-based gene cloning. We report herein a moderately saturated genetic map derived from this RIL population that incorporates codominant microsatellite (simple sequence repeat, SSR) markers and two architectural traits, little leaf (ll) and determinate (de) growth habit. Of 821 cucumber genomic SSR primer pairs evaluated for map construction, 140 (17.0%) were polymorphic between the mapping parents. In combination with 42 previously mapped SCAR and SSR makers, these polymorphic markers were employed to construct a 176-point linkage map spanning ~ 400 cM across seven linkage groups (LG). The numbers of loci mapped in LG 1 through 7 were 11, 6, 35, 18, 46, 45, and 15, respectively. The ll locus was flanked by SSR02355 and SSR03940 (4.2 and 3.6 cM from ll, respectively), and de was flanked by CSWCTT14b and SSR13251 (1.4 and 4.2 cM from the de, respectively). The SSR markers linked with the de and ll genes were mapped to Chromosome 6, and no recombination suppression was detected among the mapped loci examined. This Gy-7 × H-19 RIL-based genetic map shared 94 marker loci in common with a previously reported RIL-based linkage map derived from a wide cross between C. s. var. sativus line Gy-14 and C. s. var. hardwickii Alef. R. PI 183967. Comparative mapping supported previous findings that genomic differences (likely chromosomal rearrangements) exist between Gy-14 and PI 183967.