Salinity tolerance in barley during germination——homologs and potential genes

Salinity affects more than 6%of the world’s total land area,causing massive losses in crop yield.Salinity inhibits plant growth and development through osmotic and ionic stresses;however,some plants exhibit adaptations through osmotic regulation,exclusion,and translocation of accumulated Na+or Cl-.Currently,there are no practical,economically viable methods for managing salinity,so the best practice is to grow crops with improved tolerance.Germination is the stage in a plant’s life cycle most adversely affected by salinity.Barley,the fourth most important cereal crop in the world,has outstanding salinity tolerance,relative to other cereal crops.Here,we review the genetics of salinity tolerance in barley during germination by summarizing reported quantitative trait loci(QTLs)and functional genes.The homologs of candidate genes for salinity tolerance in Arabidopsis,soybean,maize,wheat,and rice have been blasted and mapped on the barley reference genome.The genetic diversity of three reported functional gene families for salt tolerance during barley germination,namely dehydration-responsive element-binding(DREB)protein,somatic embryogenesis receptor-like kinase and aquaporin genes,is discussed.While all three gene families show great diversity in most plant species,the DREB gene family is more diverse in barley than in wheat and rice.Further to this review,a convenient method for screening for salinity tolerance at germination is needed,and the mechanisms of action of the genes involved in salt tolerance need to be identified,validated,and transferred to commercial cultivars for field production in saline soil.

Pleiotropy Structures Plant Height and Seed Weight Scaling in Barley despite Long History of Domestication and Breeding Selection

Size scaling describes the relative growth rates of different body parts of an organism following a positive correlation.Domestication and crop breeding often target the scaling traits in the opposite directions.The genetic mechanism of the size scaling influencing the pattern of size scaling remains unexplored.Here,we revisited a diverse barley(Hordeum vulgare L.)panel with genome-wide single-nucleotide polymorphisms(SNPs)profile and the measurement of their plant height and seed weight to explore the possible genetic mechanisms that may lead to a correlation of the two traits and the influence of domestication and breeding selection on the size scaling.Plant height and seed weight are heritable and remain positively correlated in domesticated barley regardless of growth type and habit.Genomic structural equation modeling systematically evaluated the pleiotropic effect of individual SNP on the plant height and seed weight within a trait correlation network.We discovered seventeen novel SNPs(quantitative trait locus)conferring pleiotropic effect on plant height and seed weight,involving genes with function in diverse traits related to plant growth and development.Linkage disequilibrium decay analysis revealed that a considerable proportion of genetic markers associated with either plant height or seed weight are closely linked in the chromosome.We conclude that pleiotropy and genetic linkage likely form the genetic bases of plant height and seed weight scaling in barley.Our findings contribute to understanding the heritability and genetic basis of size scaling and open a new venue for seeking the underlying mechanism of allometric scaling in plants.