Inheritance and Quantitative Trait Loci Analysis of Resistance Genes to Bruchid and Bean Bug in Mungbean (Vigna radiata L. Wilczek)

Bruchid (Callosobruchus chinenesis L.) and pod sucking bug (Riptortus clavatus Thunberg) are serious insect pests during the reproduction stage and seed storage period of legume crops worldwide. However, few sources of resistance to each of these insects have been identified and characterized, and no genetic studies have been carried out with simultaneous tests of these two insects. In this study, the inheritance of seed resistance to Callosobruchus chinenesis L. and Riptortus clavatus Thunberg was examined in a mungbean cultivar, Jangan mungbean, which was developed by backcrossing with the V2709 resistant donor. The F1, F2, and F3 seed generations were developed from the cross between susceptible and resistant parents, and evaluated for resistance to the two insects. It was found that resistance to bruchid and bean bug was controlled by a single dominant gene in the F1 and F2 seeds. However, the segregation pattern of reciprocal reaction to each insect in F2 seeds showed seeds were susceptible to each insect. These results suggest that the resistance genes in Jangan mungbean to bug and weevil are either different or closely linked with each other. A genetic linkage map 13.7 cM in length with 6 markers was successfully constructed. Two QTLs were identified for bruchid resistance, and a QTL for bean bug resistance was detected. One of the QTLs for resistance to bruchid was shared with the QTL for bean bug. These newly developed closely linked markers will be used for cloning of the resistance genes to bruchid and bean bug in the future.