2nd Sept (Sun) 9:40 - 10:20

Plenary Talk 4

Chairperson: Sachiko Isobe

Genomics of salt tolerance in wild species of genus Vigna

Ken Naito* (Genetic Resources Center, NARO)

The genus Vigna comprise several important legume crops such as cowpea (V. unguiculata), mung bean (V. radiata), black gram (V. mungo) and azuki bean (V. angularis). In addition to those, bambara ground nut (V. subterrania) is increasing its cultivation areas because of its drought tolerance. Other domesticated species are local crops but tuber cowpea (V. vexillata) is interesting because it makes not only seeds but tubers, which reminds us of “pomato.” However, the most important feature of this genus is the diversity of wild species. Vigna species are widespread throughout the tropics and subtropics, including harsh environments such as marine beach, limestone karsts, deserts and swamps. As such, though not being well-studied, the wild Vigna species are a reservoir of genes for tolerance to biotic and abiotic stresses. Currently we have been focusing on salt tolerance, because it is an important issue but no salt tolerant crops have been realized. We screened our genetic resources and found several species have independently acquired salt tolerance. RI imaging with Na-22 revealed the mechanisms of salt tolerance are totally different among the species. To elucidate the genetics of salt tolerance, we de novo sequenced the whole genomes of some wild species. We also performed QTL analysis using bi-parental crosses and revealed only one or two loci are involved in salt tolerance in each species. These results indicated evolution of salt tolerance has been a simple process with genetic change in a few genes.