Inheritance and linkage relations of genes for yellow seedling in cotton (Gossypium spp.)

Genetical studies of chlorophyll deficient lethal seedling were undertaken in two G. hirsutum progenies, viz., N-3-19-18-3-5-7-1-20 and N-3-19-27-7-12-1-27. Digenic segregation in the ratio of 15:1 for normal green and pale yellow lethal seedlings indicated that the lethal trait was controlled by duplicate recessive genes. In F₂ populations of five interspecific crosses, similar segregational pattern was observed. In the G. hirsutum progeny N-3-19-27-7-12-1-27 cinus colour (red vs. green) was controlled by the dominant genes segregating in the ratio of 11 red: 5 green, while in F₂ populations obtained from interspecific cross 188-26-7-3-x 21-4-4, this character segregated in the ratio of 13 red: 3 green, showing inhibitory action of genes. Hypocotyle colour (red vs. green) was caused by two dominant genes behaving in complementary manner (7:9) in the G. hirsutum progeny, while it showed duplicate epistasis with segregation ratio of 15 red: 1 green in F₂ population derived from G. hirsutum x G. hirsutum cross. The loci controlling normal vs. pale yellow lethal seedlings, cinus and hypocotyle (red vs. green) were found to be linked. The crossover values estimated to be 18.92% between genes for seedling colour and cinus colour, 34.07% between genes for seedling colour and hypocotyle colour, and 29.06% between loci for cinus and hypocotyle colour.