Transcriptome analysis of brassinolide under low temperature stress in winter wheat

Low temperatures are the main abiotic factor affecting wheat growth. Brassinolide is a novel plant hormone that can improve the cold resistance of plants; however, the molecular mechanism of brassinolide in winter wheat at low temperatures remains unclear. In this study, winter wheat Dongnong dongmai 1 was sprayed with 0.01, 0.1, or 1.0 mg·L(–1) brassinolide (BR) at the three-leaf stage, and tillering nodes were sampled at different temperatures (5, –10 and –25 °C), and then physiological indexes were determined and the transcriptome was sequenced. The results showed that the optimum concentration of brassinolide for cold resistance is 0.1 mg·L(–1). A total of 15 302 (8198 upregulated and 7104 downregulated) differentially expressed genes (DEGs) were identified in the B1 vs D1 comparison (B1 represents 5 °C 0.1 mg·L(–1) BR treatment, D1 represents 5 °C control); 3386 (1930 upregulated and 1456 downregulated) differentially expressed genes (DEGs) were identified in the B2 vs D2 comparison (B2 represents –10 °C 0.1 mg·L(–1) BR treatment, D2 represents –10 °C control); and 2684 (2102 upregulated and 582 downregulated) differentially expressed genes (DEGs) were identified in the B3 vs D3 comparison (B3 represents –25 °C 0.1 mg·L(–1) BR treatment, D3 represents –25 °C control). Further studies showed that these DEGs were mainly involved in carbon fixation in photosynthetic organs, photosynthesis and plant–pathogen interactions, all of which were related to stress and energy metabolism. This indicates that brassinolide can produce substances that improve cold resistance in wheat seedlings. This study provides a theoretical basis for further research on the improvement of cold resistance in winter wheat by brassinolide.