The Correlations of Barley Vitality and Storage Reserve Mobilization during Early Germination

Abstract

The elucidation of the genetic relationship about storage reserve mobilization and enzymatic activity during barley germination is of particular importance for breeding and malt production. In addition to plant hormones such as gibberellic acid (GA) and abscisic acid (ABA), recent research has highlighted the importance of reactive oxygen species (ROS) signaling with hydrolase induction and plant growth. In this study, the correlation of barley vitality and mobilization of storage reserves during early seed germination was investigated. The activity of important hydrolases, as well as ROS-producing NADPH (nicotinamide adenine dinucleotide phosphate) oxidases, was monitored between six different cultivars. Associated gene expression from imbibition to germination was also analyzed by correlation analysis and cluster analysis. During early germination, the activities of α-amylase, limit dextrinase, and β-glucanase had significant positive correlations with each other and affected seed germination. Gene expression analysis showed that RbohB1 and RbohF1 (NADPH oxidases) had strong correlations with AMY1 (α-amylase) and LD (limit dextrinase). The GA synthesis gene GA3ox2 was found to have a significant correlation with protease genes Cys (cysteine protease) and Ser (serine protease), while the ABA synthesis gene NCED1 (nine-cis-epoxycarotenoid dioxygenase) had significant negative correlations with Cys and GA3ox2. Gene expression and enzyme assays indicated that NADPH oxidase, α-amylase, and limit dextrinase correlated well with barley vitality during early germination. The expression of the GA synthesis genes correlated well with glucanase and protease. These results provide information about barley gene regulation by analyzing correlations between genes.