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

Abstract

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 n2 locus which is recessive to the seed fuzz phenotype. Data from the F2, BC1F1, F2:3, and BG1F2 populations of DP 5690 × 143 fit a two-loci model for expression of the recessive fuzzless seed phenotype. Fuzzless seeds were obtained in n2n2 plants when a second recessive locus (n3) was present. The dominant N3 allele found in DP 5690 confers the fuzzy seed phenotype in homozygous n2 plants. Accession 243 of the MOVC carries the N1 locus, which is dominant to the presence of seed coat fuzz. No variation from expected ratios was observed in the F2, BC1F1, F2:3, and BC1F2 populations of the DP 5690 × 243 cross. The N3 allele had no apparent effect on the expression of the N1 locus. In a cross between accessions 243 × 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 × MD 17 fiberless, we demonstrated that at least three loci were involved in the expression of the fiberless phenotype. The involvement of n2 and n3 in the expression of this fiberless phenotype was demonstrated in the F2 progeny of the cross between 143 × MD 17 fiberless. This is the first demonstration that N1, n2, and n3 interacted to produce fiberless seed.