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 F₂ and BC₁ generations. F₂ 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 × fuzzy‐linted, the F₂ segregation ratios were 9 : 39 : 16 whereas the BC₁F₁ segregation ratios from the F₁ 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 N₁, N₂, Li₃ and Li₄, where N₁ N₁ confers the presence of fuzzy, N₂N₂ confers inhibition of fuzzy initiation and development, and duplicate gene pairs, Li₃Li₃ and Li₄Li₄, determine the presence of lint. Homozygosity for li₃li₃ and li₄li₄ might also inhibit fuzz from development. In other words, they were recessive epistatic to fuzz genes.