Genetic variants of HvGlb1 in Tibetan annual wild barley and cultivated barley and their correlation with malt quality

Improvement of malt quality is the most important objective in malt barley breeding. The current experiments investigated the variation of malt quality characters among barley genotypes and the difference in genetic variants of HvGlb1, encoding β-glucanase isoenzyme I, between Tibetan annual wild barley and cultivated barley. The correlation between the gene variants and malt quality showed that there was a large difference in the four malt quality parameters, i.e. Kolbach index, diastatic power (DP), viscosity and malt extract, among the analyzed barley cultivars. Kolbach index was negatively and positively correlated with viscosity and malt extract, respectively, while malt extract was negatively correlated with viscosity. Malt β-glucan content was a major determinant of malt quality, and was significantly correlated with Kolbach index (−0.633), malt extract (−0.333) and viscosity (0.672). On the other hand, malt β-glucan content was mainly controlled by malt β-glucanase activity. The correlation analysis showed that the HvGlb1 gene was correlated with malt β-glucan content and three of four main malt quality parameters, except DP. In addition, we also found that the HvGlb1 of Tibetan barley had wider diversity in haplotype than that of the cultivated barley, supporting the hypothesis that Tibet is one of the original centers of cultivated barley.