Study on the inheritance of wheat streak mosaic virus resistance using diallel cross method

To evaluate the mode of inheritance of resistance to wheat streak mosaic virus (WSMV) resistance and estimation the genetic parameters of resistance, five relatively tolerant wheat genotypes (Chamran, Niknejad, Adl cross, Falat and line 4004), along with a sensitive cultivar, Marvdasht, were crossed in a full- diallel crossing design. Parents, F1's and reciprocal crosses were inoculated at the seedling stage (2-3 leaves) and evaluated for reaction to the disease under greenhouse conditions by a 0-7 scale. Data were analyzed according to Hayman- Jinkes method and Griffing's method 1 model 1. General combining ability (GCA) and specific combining ability (SCA) effects for WSMV resistance were highly significant (P<0.01), indicating that both additive and nonadditive genetic effects are involved in the inheritance of resistance to WSMV. The reciprocal effects were not significant (P<0.05). The ratio of GCA/SCA variance components was relatively large (0.88), indicating that additive gene effects were more important than nonadditive effects in the control of WSMV resistance in these crosses. Therefore, progeny performance can be adequately predicted just by GCA effects. The results of Wr+ Vr and Wr- Vr analysis of variance, regression analysis of Wr and Vr indicated the importance of all additive, dominance and epistasis effects. Broad and narrow- sense heritability were 88.8 and 54.5%, respectively. Theestimation of genetic parameters showed that, additive gene effects were more important than nonadditive effects in inheritance of resistance to WSMV.