Genetic control of common bean (Phaseolus vulgaris) resistance to powdery mildew (Erysiphe polygoni)

Genetic control of common bean (Phaseolus vulgaris) resistance to powdery mildew (Erysiphe polygoni) was studied using segregating populations from the bean variety crosses Jalo x ESAL 686 and ESAL 550 x ESAL 686. F-2 plants, together with the parents, were inoculated and evaluated using a scale of values from one (plant without symptoms) to nine (completely infected plant). F-2 plants were harvested individually, and F-2:3 families were obtained. These families were evaluated in an 11 x 11 and 12 x 12 simple lattice statistical design for the Jalo x ESAL 686 and ESAL 550 x ESAL 686 crosses, respectively, using the same value scale as the F-2 generation. The segregation observed in F-2 plants and F-2:3 families indicated that two genes are involved in genetic control, due to a double recessive epistasis. The high linear regression coefficient (b) between F-2 plants and their F-2:3 family, 0.66 far ESAL 550 x ESAL 686 cross, and 0.71. for Jalo x ESAL 686 cross, showed that the trait is highly heritable.