Characteristics of a virescent cotton mutant

The virescent cotton (Gossypium hirsutum) mutant described here differs from normal cultivated cotton by a single mutation in the nucleus. The mutant exhibits nuclear control of chlorophyll and carotenoid development. Young leaves are distinctly yellow and become green with age. There is no unusual photometabolism of ¹⁴CO₂ or ¹⁴C-acetate in this mutant. It is probable that the nuclear virescent mutation is in a locus concerned with making structural units. The yellow leaves do show a high photosynthetic capacity on a chlorophyll basis. At saturating light intensity the rate of CO₂ fixation is 8 fold higher than the green control leaves. Thus, impaired pigment synthesis which could be lethal is offset by a high photosynthetic capacity in the virescent leaves.