PEG-simulated drought stress and spike in vitro culture are used to study the impact of water stress on barley malt quality

Abstract

Water deficient or drought stress is a major factor causing deterioration or instability of malt barley quality. In the studies on the influence of drought stress during grain filling on malt quality formation or metabolic changes, it is quite difficult to obtain the uniform plant individuals and water condition in pot or field experiments. In this study, we combined barley spike in vitro culture and PEG-6000 simulated drought to determine the genotypic difference in the changes of grain metabolites and the expression level of the genes encoding β-amylase and β-glucan using two Tibetan wild barley accessions and two cultivated genotypes differing in malt quality stability under drought stress. Under simulated drought, grain weight and β-glucan content were dramatically reduced and β-amylase activity was increased, and a lot of metabolites were markedly changed for all genotypes. On the whole, the changes were relatively smaller in the wild barley. Meanwhile, the expressions of Bmy1 related to β-amylase synthesis and GSL1, GSL4 and GSL7 related to β-glucan synthesis were up-regulated and down-regulated under drought stress, respectively, being consistent with the changes of β-amylase activity and β-glucan content in the four barley genotypes. The current results showed that PEG-6000 simulated drought and spike in intro culture may provide the basically similar information on grain development or metabolites as do in the field experiments, and it is suitable for use in studies on the influence of drought stress on quality traits during grain filling stage of barley or other cereal crops.