Genetic analysis of presence and absence of lint and fuzz in cotton

Cotton fibre mutants that were fuzzless and/or lintless were crossed with each other and a normal genotype (fuzzy, linted) to produce F 2 and BC 1 generations. F 2 segregation ratios from the cross of fuzzless-lintless × fuzzy-linted, for fuzzy-linted, fuzzless-linted and fuzzless-lintless were 45: 15: 4, From the cross of fuzzless-lintless x fuzzy-linted, the F 2 segregation ratios were 9: 39: 16 whereas the BC 1 F 1 segregation ratios from the F, backcrossed to fuzzless-lintless were 1: 3: 4. These data suggest that the presence or absence of lint and fuzz are controlled by the interaction of four gene loci on non-homologous chromosomes. We designate these loci as N 1 , N 2 , Li 3 and Li 4 , where N 1 N 1 confers the presence of fuzzy, N 2 N 2 confers inhibition of fuzzy initiation and development, and duplicate gene pairs, Li 3 Li 3 and Li 4 Li 4 , determine the presence of lint. Homozygosity for li 3 li 3 and li 4 li 4 might also inhibit fuzz from development. In other words, they were recessive epistatic to fuzz genes.