Diversity and Evolution of Salt Tolerance in the Genus Vigna

Abstract

Breeding salt tolerant plants is difficult without utilizing a diversity of wild crop relatives. Since the genus Vigna (family Fabaceae) is comprised of many wild relatives adapted to various environmental conditions, we evaluated the salt tolerance of 69 accessions of this genus, including that of wild and domesticated accessions originating from Asia, Africa, Oceania, and South America. We grew plants under 50 mM and 200 mM NaCl for two weeks and then measured the biomass, relative quantum yield of photosystem II, leaf Na+ concentrations, and leaf K+ concentrations. The accessions were clustered into four groups: the most tolerant, tolerant, moderately susceptible, and susceptible. From the most tolerant group, we selected six accessions, all of which were wild accessions adapted to coastal environments, as promising sources of salt tolerance because of their consistently high relative shoot biomass and relative quantum yield. Interestingly, variations in leaf Na+ concentration were observed between the accessions in the most tolerant group, suggesting different mechanisms were responsible for their salt tolerance. Phylogenetic analysis with nuclear DNA sequences revealed that salt tolerance had evolved independently at least four times in the genus Vigna, within a relatively short period. The findings suggested that simple genetic changes in a few genes might have greatly affected salt tolerances. The elucidation of genetic mechanisms of salt tolerances in the selected accessions may contribute to improving the poor salt tolerance in legume crops.

Mapping patterns of abiotic and biotic stress resilience uncovers conservation gaps and breeding potential of Vigna wild relatives

“…Traits to tolerate heat tolerance include membrane stability, pollen viability, and anther dehiscence, and decline in GABA (γ-aminobutyric acid) declination and increase in antioxidant enzymes, among other traits during plant development 10,13,14 . Traits related to salinity tolerance include relative quantum yield of photosystem II, leaf Na+ and K+ concentrations, malondialdehyde (MDA) levels, and antioxidant enzyme activities 15,16 .Major production challenges related to biotic stress for several Vigna crops include legume pod borer and Yellow Mosaic Disease (YMD) (R. Nair, pers. comm., World Vegetable Center).…”

Understanding patterns of abiotic and biotic stress resilience to unleash the potential of crop wild relatives for climate-smart legume breeding

“…The presence of salinity tolerance in 17 percent of taxa compared with three percent drought-tolerant taxa, suggest that Vigna taxa are good at developing salt-tolerant traits compared with drought-tolerant traits, and which would only require a few gene changes 8 . Many wild Vigna taxa occur naturally in coastal areas and are adapted to a saline environment 28 .…”

“…We delineated four gene pools following intercrossing studies, which was complemented by genomic, phylogenetic, and biosystematics studies (Text S1). Taxa names were revised according to GRIN taxonomy 7 and Iseki et al 8 (Table S1). The Vigna ex situ conservation status was determined with data from the 2017 WIEWS database 9 and the online platform Genesys 10 .…”

“…For the assessment of abiotic stress resilience, we carried out an ecogeographic analysis. This analysis was complemented with scores on a 1-5 Likert scale of high to low tolerance of Vigna taxa to dehydration and salinity in pot experiments, which were carried out by the Genetic Resources Center of the Japanese Agriculture and Food Science Organization 8,20 . All taxa, which scored 1 for at least one accession in the pot experiments, were identified in this paper as taxa with a high level of tolerance.…”

Screening and Identification of SSR Markers for Genetic Diversity for Mungbean [Vigna radiata (L.) Wilczek]

“…Genetic diversity is the base for crop genetic improvement and important for the conservation, evaluation and utilization of crop germplasms (Rao and Hodgkin 2002;Wang et al, 2015 andAnumalla et al, 2015). The assessment of genetic diversity will predict the phylogeny and evolution of species and to characterize genotypes (Simon et al, 2007 andIseki et al, 2016). So far very limited work has been done for the genetic improvement of mungbean crop and continuous to be neglected compare to the other major legume crops such as soybean, cowpea and common bean, or even with comparison with one of its relative, but the less economically important, azuki bean.…”