Abstract:

Mungbean [Vigna radiate (L.) Wiclzek] is one of the main edible beans in China while bruchid are serious devastating stored pests of grain legumes causing considerable loss to mungbean. The most important of the bruchid beetle in Asian is Callosobruchus chinensis (L). Breeding for bruchid-resistant cultivars is a major goal in mungbean improvement. In this study, we analyzed the QTLs, using a Recombinant-inbred-lines (RIL) population from the cross between a highly susceptible economical parent Berken and a highly resistant wild parent ACC41. The RIL population together with their parents were planted in three sites (Australia, Beijing and Nanjing) and evaluated for their resistance by infesting with C. chinensis in 2005 and 2006 in our laboratory. We set the combination of a plant site and a year as an environment, so there are four environments (Australia 2005, Australia 2006, Beijing 2006, and Nanjing 2006). Chi-square analysis (χ²) of the RIL population showed that except for the accessions planted in Beijing field and tested for resistance in 2006, the accessions in other three environments supported the 1:1 segregation ratio. This clearly indicated there was a major resistant gene in ACC41 suitable for mapping. A genetic linkage map with 79 RFLP markers was constructed. Software WinQTLCart was applied to detect QTLs. As a result, a QTL named brI on group 9 steadily existed in the four environments and LOD was 12.99 to 115.12, explaining 74.05 to 79.27% of the phenotypic variations. It is a major QTL for bruchid resistance. The additive effect of the QTL was negative indicating that the allele of the loci from ACC41 promotes the resistance. It will be beneficial to bruchid-resistant breeding and plays an important role in mapping and cloning of the bruchid-resistant genes.

Key words: Mungbean, Bruchid, Recombinant-inbred-lines (RIL) Population, Quantitative trait loci (QTL)