Drought stress is one of the main factors restricting hulless barley (Hordeum vulgare L. var. nudum Hook. f.) yield. Genome-wide association study was performed using 269 lines of hulless barley to identify single-nucleotide polymorphism (SNP) markers associated with drought-resistance traits. The plants were cultured under either normal or drought conditions, and various quantitative traits including shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, leaf fresh weight, leaf saturated fresh weight, leaf dry weight, ratio of root and shoot fresh weight, ratio of root and shoot dry weight, shoot water loss rate, root water loss rate, leaf water content and leaf relative water content, and field phenotypes including main spike length, grain number per plant, grain weight per plant, thousand grain weight (TGW), main spike number, plant height, and effective spike number of plants were collected. After genotyping the plants, a total of 8,936,130 highly consistent population SNP markers were obtained with integrity > 0.5 and minor allele frequency > 0.05. Eight candidate genes potentially contributed to the hulless barley drought resistance were obtained at loci near significant SNPs. For example, EMB506, DCR, and APD2 genes for effective spike number of plants, ABCG11 gene for main spike number (MEN), CLPR2 gene for main spike length, YIP4B gene for root and shoot dry weight (RSWD), and GLYK and BTS genes for TGW. The SNPs and candidate genes identified in this study will be useful in hulless barley breeding under drought resistance.

Cultivated barley (Hordeum vulgare L.) has been proven to be an economically important model plant and having large genetic diversity among the species. The effective exploitation of qualitative characters in barley can be measured by its genetic diversity and interrelationship. This study aims to determine the assessment of genetic diversity in Chinese hulless barley accessions for qualitative traits. Presently, in this study, the genetic diversity of 208 Chinese hulless barley from different Provinces of China, 111 genotypes were from the Tibet plateau, 30 Sichuan, 2 USA, 1 Canada, 12 Gansu, 51 Qinghai, 1 Yunnan was investigated; collected. Almost all the qualitative traits including crude protein, fiber, starch, neutral detergent fiber, and acid detergent fiber exhibited significantly high variability (p≤0.0001) among the cultivars. The data were analyzed using Statistics 8.1. In this study, significantly high variation was observed between starch content and neutral detergent fiber (23.64% and 11.54%). However, the highest diversity is based on the magnitude of the coefficient of variation exhibited in crude protein (13.82%), starch (12.87%), and fiber (12.17%). There was a significantly positive correlation between fiber, acid detergent fiber, and neutral detergent fiber except for starch content with crude protein and fiber that exhibited a significant negative correlation (r= -0.38*** and r= -0.92***). A large genetic diversity was observed through cluster analysis among all the 208 barley accessions, distance coefficient ranging between 0.28 and 75.86. The histogram revealed that frequency distributions of 208 different genotypes of hulless barley crop with all five different characters, crude protein, fiber, starch, neutral detergent fiber, and acid detergent fiber, showed normal distribution. It is concluded that this hulless barley study showed genetic diversity among the accessions and confirmed genetic diversity in various traits used.

Hull-less barley (HB) has gained attention for its various health supplements and use in beer brewing across China. The role of HB is somewhat limited, accounting for only 2% of the total production for human food; while approximately 6% is used in malt production, HB contains multiple key ingredients and functional components beneficial for health. These include dietary fiber (DF), protein, starch, and barley malt. These components are instrumental in promoting health benefits, including cardiovascular protection, glycemic regulation, lowering blood cholesterol levels, reducing the risk of colorectal cancer, improving cellular signaling, producing short-chain fatty acids (SCFAs), and promoting the growth of beneficial gut microflora. The structural characteristics of HB, such as size and shape, which are important in influencing these traits, are briefly discussed. Additionally, genetics insights into these traits are vital for understanding the molecular mechanisms and gene expression in response to environmental factors. By leveraging genetic studies, we explore the biosynthesis pathways and quantitative trait loci (QTL) regions that influence these health-promoting traits. Given its versatility, HB has the potential to improve cardiovascular health, supporting nutritional food goals, and enhance malting quality. This review highlights HB’s nutritional profile and genetic potential, showing its promise in supporting both health goals and the malting industry.