Transcriptomic and Metabolomic Analyses of the Effects of Exogenous Trehalose on Heat Tolerance in Wheat.

Trehalose can improve the tolerance of plants to various types of environmental stress. Nonetheless, information respecting the molecular networks of wheat seedlings to exogenous trehalose under heat stress is limited. Here, two wheat varieties pretreated with exogenous trehalose were selected to explore the molecular mechanism by which trehalose improves the heat tolerance of wheat (Triticum aestivum L.). The results indicated that exogenous trehalose improved the physiological state of wheat seedlings under heat stress. Through RNA sequencing and metabolomics analysis, the genes and metabolites specifically expressed in trehalose pretreatment were identified. After heat stress, there were 18,352 differentially expressed genes (DEGs) in the control and trehalose-treated (H_vs_TreH) groups of Yangmai 18 and 9045 DEGs in Yannong 19. Functional annotation and enrichment analyses showed that the DEGs in the two wheat varieties were mainly involved in carbohydrate metabolism and biosynthesis of secondary metabolites. Through a liquid chromatography-mass spectrometry platform, 183 differential metabolites in H_vs_TreH groups of Yangmai 18 and 77 differential metabolites in Yannong 19 were identified. Compared with the control group, many protective metabolites, such as amino acids, purines, phenylpropanoids and flavonoids, showed significant differences under heat stress. The results indicated that exogenous trehalose protected the wheat biomembrane system, enhanced carbohydrate metabolism and signal transduction, strengthened the activity of the tricarboxylic acid cycle (TCA cycle), regulated purine metabolism, gene expression and metabolite accumulation in the phenylpropanoid biosynthesis and flavonoid biosynthesis pathways, thus improving the heat tolerance of wheat.

Physiological and Transcriptomic Analyses Reveal Exogenous Trehalose Is Involved in the Responses of Wheat Roots to High Temperature Stress.

High temperature stress seriously limits the yield and quality of wheat. Trehalose, a non-reducing disaccharide, has been shown involved in regulating plant responses to a variety of environmental stresses. This study aimed to explore the molecular regulatory network of exogenous trehalose to improve wheat heat tolerance through RNA-sequencing technology and physiological determination. The physiological data and RNA-seq showed that trehalose reduced malondialdehyde content and relative conductivity in wheat roots, and affecting the phenylpropane biosynthesis, starch and sucrose metabolism, glutathione metabolism, and other pathways. Our results showed that exogenous trehalose alleviates the oxidative damage caused by high temperature, coordinating the effect of wheat on heat stress by re-encoding the overall gene expression, but two wheat varieties showed different responses to high temperature stress after trehalose pretreatment. This study preliminarily revealed the effect of trehalose on gene expression regulation of wheat roots under high temperature stress, which provided a reference for the study of trehalose.