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Barley is the fourth largest cereal crop in the world. It is mainly used for feeding, beer production and food. Barley is receiving more attention from both agricultural and food scientists because of its special chemical composition and health benefits. In comparison with other cereal crops, including wheat, rice and maize, barley grains are rich in dietary fiber (such as β-glucan) and tocols, which are beneficial to human health. It is well proved that diets rich in those chemicals can provide protection against hypertension, cardiovascular disease, and diabetes. Barley has been widely recognized to have great potential as a healthy or functional food. In this review, we present information about studies on the physical structure of the barley grain and the distribution of its main chemical components, nutrient and functional composition of barley grain and their health benefits, and the approaches of improving and utilizing the nutrient and functional chemicals in barley grain. With the development of processing technologies, functional components in barley grains, especially β-glucan, can be efficiently extracted and concentrated. Moreover, nutrient and functional components in barley grains can be efficiently improved by precise breeding and agronomic approaches. The review highlights the great potential of barley used as healthy and functional foods, and may be instructive for better utilization of barley in food processing. [ABSTRACT FROM AUTHOR]

β-glucan is an important trait to be improved in barley breeding programs, as it greatly affects the quality of the end products when barley grains are used as raw material of feed or malt production or consumed as food for human. Although the genes associated with β-glucan synthesis have been identified, genetic regulation of β-glucan accumulation in barley grains is still completely unclear. In this study, 100 accessions from International Barley Core Selected Collection (BCS) were planted in two environments for two consecutive years to determine the genotypic variation of grain β-glucan content. A genome-wide association study (GWAS) identified 14 stable marker-trait associations (MTAs) (−Log10(P)> 4) for grain β-glucan content. Significantly positive correlation was found between grain β-glucan content and the number of favorable alleles of 14 stable MTAs. Seven putative candidate genes encoding some enzymes in glucose metabolism were found to be associated with β-glucan content. One of the putative genes, HORVU6Hr1G088380, could be an important gene controlling barely β-glucan content, with the SNPs being closely linked in all tested accessions and divided into two haplotypes. High resolution melting (HRM) analysis of the first SNP suggested that the HRM-SNP marker is valid for marker-assisted selection in barley breeding. This study provides useful information for the genes and markers related to grain β-glucan content in barley. [ABSTRACT FROM AUTHOR]

Phenolic acids in plants is receiving more attention because of their nutritive function and essential roles in plant growth. However, the genetics of phenolic acids in barley is still unclear. In this study, two main phenolic acids, i.e. ferulic acid (FA) and p-coumaric acid (p-CA), were analyzed in the grains of a double haploid population derived from XZ153 (Tibetan wild barley) × Hua30 (cultivated cultivar) grown in three locations. A wide variation in the content of phenolic acids was observed among the DH population. Quantitative trait locus (QTL) analysis of phenolic acid content in barley grains from three locations totally identified 4 QTLs associated with p-CA content and 4 QTLs with FA content. Based on the mean phenolic acids content over the three locations, two significant QTLs (M_3261686 for p-CA and M_4184755 for FA), belonging to cytochrome P450 family (HvCYPs) were identified, with the LOD value of 5.33 and 7.01 respectively. These two QTLs could account for 14% of phenotypic variation for FA and 18% for p-CA. Collinearity analysis revealed that HvCYPPA (QTL for p-CA) has duplication events in barley genome. Furthermore, there was no synteny block found for these two genes in barley genome. The current results provide a new knowledge about genetic controlling of phenolic acids synthesis in barley grains. [ABSTRACT FROM AUTHOR]

The cultivar and environmental variations of β-glucan content and β-glucanase activity in grains and malt were investigated in 8 barley cultivars grown at 7 locations. On average, for all cultivars and locations, approximately 80% of β-glucan present in grains was degraded after malting, but there was great variation among both cultivars and locations. β-glucanase activity was much lower but detectable in grains, and it dramatically increased after malting. The cultivar and environmental variations of β-glucan content were much higher in malt than in grains, and malt β-glucan content was more dependent on malt β-glucanase activity than the original level of β-glucan in grains. The correlation analysis of β-glucan content, β-glucanase activity and four malt quality parameters (Kolbach index, diastatic power, viscosity and malt extract) showed that malt-glucan content was highly significantly correlated with all quality parameters, while the association between grain β-glucan content and these quality parameters was relatively weak. Malt β-glucan content was negatively and highly significantly correlated with malt β-glucanase activity, and positively and significantly correlated with grain β-glucan content. It was also found that there was a positive and significant correlation between grain and malt β-glucanase activity. [Copyright &y& Elsevier]

Genotypic variation in kernel heavy metal concentrations was studied for barley Hordeum vulgare L.) cultivars grown in six locations of Zhejiang, China. These sites covered a wide range of soils and climates. The results showed that barley kernels produced at some sites contained heavy metals higher than the Maximum Permitted Concentration (MPC). Significant cultivar effects were identified, but these were less than the site effects. Although Genotype x Location effect existed, genotypes performed consistently across six locations. Meanwhile, there were significant positive correlations between heavy metal concentrations in barley grain, indicating that there is potential for developing cultivars that are low heavy metal accumulators. Soil properties such as pH and EDTA-extractable heavy metal content played an important role in heavy metal uptake and accumulation in barley. Data from the six soils showed that the soil in Ningbo was lower in pH and contained the highest EDTA-cadmium (Cd), copper (Cu), and chromium (Cr), causing significantly higher kernel Cd, Cu, and Cr concentrations in barley grains. Kernel Cd, zinc (Zn), Cr, manganese (Mn), and iron (Fe) concentrations were closer to EDTA-extractable corresponding metal contents than to soil pH. Regression equations between kernel Cd, Zn, Cr, Mn, and Fe concentrations and its EDTA-extractable contents were established and suggested to be used in predicting soil critical levels of these metals for safe barley production. [ABSTRACT FROM AUTHOR]

The content and composition of starch in cereal grains are closely related to yield. Few studies have been done on the identification of the genes or loci associated with these traits in barley. This study was conducted to identify the genes or loci controlling starch traits in barley grains, including total starch (TS), amylose (AC) and amylopectin (AP) contents. A large genotypic variation was found in all examined starch traits. GWAS analysis detected 13, 2, 10 QTLs for TS, AC and AP, respectively, and 5 of them were commonly shared by AP and TS content. qTS-3.1, qAC-6.2 and qAP-5.1 may explain the largest variation of TS, AC and AP, respectively. Four putative candidate genes, i.e., HORVU6Hr1G087920, HORVU5Hr1G011230, HORVU5Hr1G011270 and HORVU5Hr1G011280, showed the high expression in the developing barley grains when starch accumulates rapidly. The examined 100 barley accessions could be divided into two groups based on the polymorphism of the marker S5H_29297679, with 93 accessions having allele GG and seven accessions having AA. Moreover, significantly positive correlation was found between the number of favorable alleles of the identified QTLs and TS, AC, AP content. In conclusion, the identified loci or genes in this study could be useful for genetic improvement of grains starch in barley. [ABSTRACT FROM AUTHOR]

The variation in grain cadmium (Cd) concentrations was evaluated among 600 barley genotypes grown in the same field condition to select low Cd accumulating genotypes. The results showed that there is considerable genotypic variation in grain Cd concentrations in barley grain samples, with the mean concentration of 0. 16mgkg−1 DW and the variation of 0 (not detected) to 1. 21mgkg−1 DW, and 47. 2% of the grain samples exceeded the maximum permissible concentration (MPC) for Cd in cereal grains. In addition, differences between genotypes over the two years were fairly consistent, and Beitalys and Shang 98-128 showed the lowest grain Cd concentration, being 97. 5% lower than that in the two highest Cd accumulators E-barley 6 and Zhenong 8 in the second harvest year. The great genotypic differences in Cd concentrations indicated that it is possible to lower Cd content of barley through cultivar selection and breeding for use at sites where Cd concentration in grain exceeds the MPC. Significant genotypic difference was also found in microelement concentrations. Correlation analysis showed that only Mn accumulation is synergetic with Cd accumulation, despite slightly positive relationship between Cd and Zn, Cu, or Fe in accumulation in barley grains. [Copyright &y& Elsevier]