Epistasis-Driven Bias in the Estimates of Additive and Dominance Genetic Variance in Dolichos Bean (JLablab purpureus L.) Var. Lignosus

摘要

The choice of suitable selection strategy for genetic improvement of any crop species hinges on the relative contribution of additive and non-additive components of genotypic variation of economic traits. Simplified triple test cross (STTC) design wasused to detect epistasis and assess epistasis-driven bias in the estimates of additive (o2A) and dominance (o2D) components of genotypic variation of economic traits in Dolichos bean. The material for the study consisted of 12 genetically diverse inbredlines and two pairs of testers contrasting for economic traits. The 12 inbred lines were crossed to two pairs of testers in 2012 rainy season to generate two sets of STTC progenies, which were evaluated in 2013 and 2014 rainy season at the University ofAgricultural Sciences, Bengaluru, India. The results indicated an important role of epistasis in inheritance of all the traits in Dolichos bean. While delta~2_ A predominated in the inheritance of racemes I plant, delta~2 _D predominated in the inheritance of pod weight I plant. Only delta~2_A was important in the inheritance of days to flowering and seed weight/plant. The 12 inbred lines used in the study contributed significantly to varying extent to epistasisgoverning different traits in both sets of STTC progenies in both years. The bias in the estimates of o2A was greater than that in the estimates of delta~2_n. Therefore, it is not advisable to ignore epistasis in studies designed for determining the relative magnitude of delta~2_A and delta~2_D controlling target traits in Dolichos bean.