Genomic Approaches to Biotic Stresses

Average seed yield of mungbean (Vigna radiata) grown in major growing countries is low, being only about one-third to one-fourth of its yield potential. A main factor causing the low yield in mungbean is biotic stresses (disease infection and insect infestation) that happen at all stages of plant growth and development and after harvest. Common and important diseases and insect pests of mungbean include powdery mildew, Cercospora leaf spot, yellow mosaic virus, bruchids and pod sucking bugs. Employing host plant resistance is the best way to manage the diseases and insect pests. However, progress in the development of new mungbean cultivar(s) with the biotic resistance is slow due to bottleneck in evaluation for the resistance which is environmental-dependent or time-consuming, although germplasm with immune or highly or moderately resistance for these biotic stresses is available and the genetics of the resistance appears to be simple. Genomic approaches, especially gene mapping and marker-assisted selection, are promising in the acceleration of cultivar development for biotic stress resistance in mungbean. Mungbean is a slow runner in genomics research, although it is among the forefront crops targeted for genome analysis at the beginning of the crop genomics era; e.g., powdery mildew resistance and bruchid resistance in mungbean are among the plant diseases and insects being investigated nearly 30 years ago. However, the recent release of a reference genome sequence of mungbean and current advanced sequencing technology has enabled fast and efficient DNA marker development, fine-mapping and identification of candidate gene(s) for the biotic resistance in mungbean possible. This chapter covers past, present and future research on molecular and genomics approaches to biotic stresses for mungbean genetic improvement.