Polymorphism of HvDRO1 and HvqSOR1 associated with root growth angle in barley accessions

: The root growth angle (RGA) is an important breeding target that confers high crop adaptability to deleterious environments. In barley, natural variations in RGA among accessions have been observed, but many of the genetic factors that cause of this variation remains unclear. In this study, we explored the orthologs of OsDRO1 ( DEEPER ROOTING 1 ) and OsqSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1) , which play a critical role in RGA regulation in rice, from barley genome and analyzed the polymorphisms of these genes among barley accessions. BLASTP search detected putative orthologs of OsDRO1 and OsqSOR1 in barley (HvDRO1 and HvqSOR1) with more than 60% amino acid similarity. Sequence analysis identified SNPs causing mis-splicing and nonsynonymous amino acid substitution in HvDRO1 and HvqSOR1 , respectively. These SNPs were associated with RGA variation among the 47 barley accessions. Phylogenetic analysis using the 105 barley accessions revealed that the alleles of HvDRO1 and HvqSOR1 are related to the genetic background of the accessions. Further-more, the mutant allele of HvDRO1 is mainly shared in the Hokuriku/Nagano subpopulation, suggesting that the mutant allele is involved in local adaptation of barley cultivars to the soil environment of the region. Our findings suggest that the polymorphisms of HvDRO1 and HvqSOR1 are possible determinants of RGA variation in barley, at least in Japanese accessions, and provide information on allelic variants of the genes for marker-assisted selection to genetic improvement of RGA of barley.