New genetic insights into improving barley cope with salt stress via regulating mineral accumulation, cellular ion homeostasis, and membrane trafficking

Plant biologists aim for the genetic improvement of barley adaptation to salinity stress. This study was designed to explore the natural variation of responsive physiological and agronomic traits in a diverse spring barley panel under salt-affected soil and the application of selenium nanoparticles (Se-NP) during the vegetative phase. Significant phenotypic variation was detected among the accessions in response to salt stress. Application of 1 mM Se-NP enhanced thousand kernel weight (TKW) by 28% while decreasing the Na+ contents in the flag leaves by 53% . The genomic analysis lead to having in total, of 146 associated SNPs with salt-responsive traits using 19 K SNPs in a genome-wide association study analysis. High significant SNPs were located within or near candidate genes which are potentially involved in the stress tolerance mechanism via enhancing the expression of Na+/H+ antiporters and tonoplast H+-ATPase. The candidate genes include HORVU.MOREX.r3.2HG0184880 and HORVU.MOREX.r3.2HG0199370 that encodes sulfite reductase and anthocyanidin reductase, respectively, confirming the crucial role of Se-NP in improving barley salt tolerance. We further showed the allelic variation inside the genes associated with traits under Se-NP leads to enhancing the accumulation of N, P, K+, ion homeostasis, antioxidant metabolism, nitrogen uptake, and ultimately grain yield. This study provides desirable alleles for salt tolerance in barley breeding strategies.