Development and evaluation of barley mini-core collection for salinity tolerance and identification of novel haplotypic variants for HvRAF.

Background and aims: India is one of the countries being projected as the salinization hotspots in the near future. To identify novel donors imparting salt tolerance, barley mini-core collection comprising 107 Hordeum vulgare germplasm and 3 wild accessions from the Indian National Genebank were evaluated under salt stress. Methods: Barley accessions were screened under salt stress (200 mM NaCl) at early growth and the adult plant stage based on morpho-physiological traits including salt uptake parameters. Further, the possible role of candidate gene Hordeum vulgare root abundant factor (HvRAF) was studied by deciphering allelic variation and expression analysis in selected salt tolerant and susceptible accessions. Results: Analysis of variance revealed a significant effect of salinity on all traits and elucidated profound genotypic variation. Salinity caused a drastic reduction in growth and severely affected ion homeostasis resulting in decline in grain yield by 65.35% compared to control. Accessions EC0578359, EC0578251, IC0547723, EC0123148, EC0299361, EC0177250 and IC0247671 were identified as the most promising salt-tolerant genotypes. Further investigation of allelic variation in HvRAF revealed a total of 26 SNPs, of which 10 were non-synonymous, 8 were synonymous and 5 were conserved. Haplotype variant analysis indicated two major haplotypic groups (Hap 1 and Hap 2) for HvRAF, of which the Hap 2 was found to be more prevalent than Hap 1. Conclusions: Salt-tolerant phenotype exhibited the physiological basis of tolerance and upregulated expression of HvRAF, although none of the identified Hap groups could be associated with salt tolerance suggesting the governance of trait by multiple loci. [ABSTRACT FROM AUTHOR]