Sadaf Memon, Rizwan Ali Kumbhar, Shabana Memon, Shah Nawaz Mari Baloch, Rania Chourouk Benhafid, Kehan Yang, Zebaman, Longfei Zeng, Cile Duoji, Qiji Zhuoma, Mingxiang Wang, Mingyong, Xiaoqin Yang, Yajie Liu, Hui Zhao, Zongyun Feng
Hulless barley (HB) is a nutrient-rich cereal gaining renewed research interest in the Tibetan regions of China. Grain protein content (GPC) is a quality-determining trait in HB that significantly affects end-use quality and is strongly influenced by environmental factors. Identifying stable association regions and developing breeding-applicable molecular markers are breeding objectives for high-GPC HB variety improvement. This study analyzed 266 HB accessions grown across six environments (2018-2021). Phenotypic GPC ranged from 5.02% to 18.31%, with moderate heritability (H2 = 0.473) and significant G×E interaction. A genome-wide association study (GWAS) using 168,983 GBS-derived SNPs and three models (GLM, MLM, FarmCPU) revealed no Bonferroni-significant SNPs in the BLUP meta-analysis. At the suggestive threshold (p < 1 × 10-5), 40 SNPs (18 loci) showed nominal association, with chromosome 7H harboring the most robust cross-model signal. Two SNPs on chromosome 6H and 7H exceeded Bonferroni correction in Yangma-2018 under GLM and FarmCPU. Candidate gene mining revealed seven functional genes, including 30S ribosomal protein S13 and glutamate-cysteine ligase. The lead SNP S7H_6966377 was located 165 kb from 30S ribosomal protein S13. These findings establish chromosome 7H as a regulatory hub for GPC and provide markers for marker-assisted selection.