EXPRESSION OF GENES CONTROLLING THE INHERITANCE OF RESISTANCE TO COTTON LEAF CURL VIRUS DISEASE (CLCuD) IN GOSSYPIUM HIRSUTUM L.: A QUANTITATIVE ANALYSIS

Abstract

Forty cotton genotypes were screened for their responses to cotton leaf curl virus symptoms through epidemiology in field and glasshouse, and grafting inoculation during 2001 and 2002. The CLCuD disease ratings, in glasshouse and field conditions, and grafting classified /categorized the variety NIAB-111 as highly resistant and the exotic genotypes NuCOTN35B as highly susceptible parents. These two lines were hybridized to develop F1, F2, BCNu (back cross with NuCOTN-35B) and BCN1 (back cross with NIAB-111) generations to obtain information on the genetic basis of variation for CLCuD resistance through generation mean analysis. Additive- dominance model was found adequate, and the genes responsible for CLCuD resistance were, in general, dominant to their alleles responsible for CLCuD susceptibility. The narrow sense heritability (h2 NS) was moderately high for CLCuD resistance, which along with the estimates of heterosis and genetic advance suggested a potential for the development of breeding material having resistance to CLCuD. However, use of rigorous selection coupled with evaluation of the resistant plants selected from segregating material under higher viral load is suggested to develop CLCuD resistance in Gossypium hirsutum L.