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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Crop Germplasm Research » Research » Publications at this Location » Publication #74103
Title: GENETIC ANALYSIS OF TWO TERPENOID VARIANTS IN COTTON, GOSSYPIUM HIRSUTUM L.

Author
item Kohel, Russell
item BELL, ALOIS - 6202-40-15

Submitted to: Journal of Heredity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: We conducted genetic analysis of two variants transferred to Upland cotton. The variants are in the terpenoid pathway for the production of gossypol. High level of methylation (ME) was transferred from a relative of Pima cotton and raimondal (RA) accumulation was transferred from a wild species. Progeny tests of the two variants were conducted in the field to insure that the phenotypic expression was repeatable under field conditions and that plants used in the genetic analysis were homozygous. The terpenoid variants were crossed with TM-1 and the F1 terpenoid profiles were determined. The F1 with the ME line had a wild-type (WT) terpenoid profile that indicated that ME was recessively inherited. The F1 was self-pollinated to produce an F2 and BC to the ME line. Segregation in both populations confirmed that ME was conditioned by a single recessive allele, and we assigned it the symbols "meme." The F1 with the RA line expressed raimondal that indicated that RA was dominantly inherited. The F1 was self-pollinated to produce an F2 and BC to TM-1. Segregation for the RA variant was complex. In the F2 segregation was 9:7 raimondal:none, and in the BC segregation was 1:3 raimondal:none. This segregation conformed to the segregation of alleles at two loci with epistasis in which a variant allele has to be present at both loci before raimondal is produced. We assigned the gene symbols Ra1Ra1Ra2Ra2 to the RA variant. Linkage tests were conducted and neither of the terpenoid variants showed any linkage with the markers in our tests.

Technical Abstract: We conducted genetic analysis of two terpenoid variants transferred to G. hirsutum. High level of methylation (ME) was transferred from G. barbadense by direct backcrossing to G. hirsutum. Raimondal accumulation (RA), unique to G. raimondii, was transferred by producing a synthetic amphidiploid and backcrossing to G. hirsutum. Progeny tests of the two terpenoid variants were conducted in the field to insure that the phenotypic expression was repeatable under field conditions and that plants used in the genetic analysis were homozygous. The terpenoid variants were crossed with TM-1 and the F1 terpenoid profiles were determined. The F1 with the ME line had a WT terpenoid profile that indicated that ME was recessively inherited. The F1 was self-pollinated to produce an F2 and BC to the ME line. Segregation in both populations confirmed that ME was conditioned by a single recessive allele; we assigned it the symbols meme. The F1 with the RA line expressed raimondal that indicated that RA was dominantly inherited. The F1 was self-pollinated to produce an F2 and BC to TM-1. Segregation for the RA variant was complex. In the F2 segregation was 9:7 raimondal:none, and in the BC segregation was 1:3 raimondal:none. This segregation conformed to the segregation of alleles at two loci with epistasis in which a variant allele has to be present at both loci before raimondal is produced. We assigned the gene symbols Ra1Ra1Ra2Ra2 to the RA variant. Linkage tests were conducted with virescent-1, V1, cup leaf, cu, glandless-1, gl1, frego bract, fg, cluster 1, cl1, Red plant, R1, Okra leaf, L2o, Tomentum, T1, Petal spot, R2, Yellow pollen, P1, Yellow petals, Y1, Brown lint, Lc1, and Naked seed, N1. Neither terpenoid variants showed linkage with the markers in our tests.