Indian Institute of Pulses Research, Kanpur, 208 024, U.P, India.
The Vigna is one of the most important genus in the Fabaceae. Among many species of this genus, nine are domesticated as food crops. The average yields of these crops are very low due to inherently low yield potential of the present cultivars and their susceptibility to diseases like Mungbean Yellow Mosaic Virus (MYMV), powdery mildew and cercospora leaf spots. Various genomic resources have been dev.eloped for mungbean, urdbean, azuki bean and cowpea for accelerating the breeding efforts in these crops. The utility of marker assisted selections in improvement of Vigna species is limited largely due to limited marker polymorphism within the species. Efforts are being made to develop high-throughput markers with greater resolution. Different types of molecular markers such as RAPDs, RFLPs, AFLPs and SSRs have been developed and mapped onto chromosomes. These markers have been used for identification and mapping of genes and QTLs for important traits like seed weight, resistance against MYMV and powdery mildew and tolerance against bruchids. Eleven genetic linkage maps were developed so far but very few contained enough markers to condense into putative 11 linkage groups. Comparative genome mapping between mungbean and several other legumes including azuki bean, common bean, cowpea and lablab bean revealed various levels of macrosynteny. Comparison between urdbean and azuki bean maps revealed high degree of genomic colinearity. Modest beginning has been made in developing RAC libraries to facilitate map-based cloning of genes and QTLs. Advances in developing genomic resources such as linkage maps, high-throughput markers and RAC libraries will be helpful to accelerate genetic improvement of Vigna species.
