Genetic characterization of root architectural traits in barley (Hordeum vulgare L.) germplasm using SNP markers

Increasing attention is paid to providing tools to breeders to underpin targeted breeding for specific root traits that may be useful in low-fertility, drying soils; however, such information is not available for barley (Hordeum vulgare L.). We phenotyped 191 barley accessions from Australia for 26 root and shoot traits using the established semi-hydroponic system, and identified significant variation (CV >=0.25) for 16 of the traits evaluated. The population structure and marker-trait association (MTA) were assessed using 21,061 high-quality genotyping-by-sequencing (GBS)-based single nucleotide polymorphism (SNP) markers. The population structure analysis of the barley panel identified six distinct groups. A total of 435 significant (P <0.001) MTAs were detected with r2 values up to 0.18. The strongest marker-trait associations were found in root length and root dry weight in the top 20 cm, and root volume. Based on physical locations of these MTAs in the barley genome, 33 putative QTL were identified for the root traits, and nine QTL for shoot traits. Among these, seven major QTL shared the same physical regions in the barley genome. The genomic region 640-651 Mb on chromosome 7H was significant for three root traits (lateral root biomass, total root biomass and root biomass in the top 20 cm) and one shoot trait (shoot biomass) and included 440 candidate genes. The putative QTL for various root traits identified in this study would be useful for enhancing adaptation of new barley cultivars to suboptimal environments and abiotic stresses.Keywords: Barley, genotyping-by-sequencing, SNP markers, association mapping, root traits