Phytohormone,as a signaling molecule,plays an important role in plants response to low temperature stress.Dongnong Dongmai 1 was used as experimental material in this study. To investigate the effect of exogenous MeJA on the cold tolerance physiology and the expression of TaPDF1.2, TaCOI1 and TaMYC2 genes in wheat,the leaves were sprayed with 0.5,1.0,and 2.0 mmol·L-1 MeJA at the trifoliate stage,and leaves and tillering node were collected at 5 ℃,0 ℃,-10 ℃,and -25 ℃ under natural cooling conditions in field. The results showed that MeJA treatment reduced the relative electrical conductivity and MDA content of leaves and tillering node of Dongnong Dongmai 1 under low temperature stress,increased the accumulation of proline,soluble sugar and soluble protein,and increased the activities of antioxidant enzymes SOD,POD and CAT.Among different treatment concentrations,1.0 mmol·L-1 MeJA performed best and the overwinter survival rate was 91.5%. At -10 ℃,the accumulation of protective substances in the leaves and tillering node was the highest,and the protective enzyme activity was the strongest. Compared to leaves, tillering node of Dongnong Dongmai 1 are more resistant to cold. Treatment with 1.0 mmol·L-1 exogenous MeJA significantly increased the expression of TaPDF1.2, TaCOI1,and TaMYC2 genes in leaves and tillering node of Dongnong Dongmai 1 under low temperature stress. |