Identification of a third fuzzless seed locus in upland cotton (Gossypium hirsutum L.)

Segregating populations were developed to evaluate the inheritance of the fuzzless seed phenotypes in upland cotton (Gossypium hirsutum L.). Accession 143 of the Mississippi Obsolete Variety Collection (MOVC) has a fuzzless seed phenotype. This line carries the n(2) locus which is recessive to the seed fuzz phenotype. Data from the F-2, BC1F1, F-2:3, and BC1F2 populations of DP 5690 x 143 fit a two-loci model for expression of the recessive fuzzless seed phenotype. Fuzzless seeds were obtained in n(2)n(2) plants when a second recessive locus (n(3)) was present. The dominant N-3 allele found in DID 5690 confers the fuzzy seed phenotype in homozygous n2 plants. Accession 243 of the MOVC carries the N-1 locus, which is dominant to the presence of seed coat fuzz. No variation from expected ratios was observed in the F-2, BC1F1, F-2:3, and BC1F2 populations of the DP 5690 x 243 cross. The N-3 allele had no apparent effect on the expression of the N-1 locus. In a cross between accessions 243 x 143, a few plants were observed which were completely devoid of lint and fuzz fiber (fiberless). A fiberless line was developed from one of these fiberless plants. This line was designated MD 17 fiberless. In a cross between DP 5690 x MD 17 fiberless, we demonstrated that at least three loci were involved in the expression of the fiberless phenotype. The involvement of n(2) and n(3) in the expression of this fiberless phenotype was demonstrated in the F-2 progeny of the cross between 143 x MD 17 fiberless. This is the first demonstration that N-1, n(2), and n(3) interacted to produce fiberless seed.