Research On The Mechanism Of Ethylene-Induced Leaves Abscission Of Chinese Cabbages And The Regulation Of 1-MCP

Chinese cabbage(Brassica rapa,subspecies pekinensis and chinensis)is a kind of vegetable of the genus Brassica,which can be stored for 3-4 months under low temperature conditions.However,it is prone to leaves abscission during storage during storage.The phenomenon of leaves abscission has led to a decline in the value of commodities and considerable economic losses.Ethylene can promote the shedding of some plant organs,and the ethylene receptor inhibitor 1-methylcyclopropene(1-MCP)has a certain inhibitory effect on the shedding of some plant organs.The experiment used exogenous ethylene treatment(100 ?L/L),1-MCP treatment(0.75 ?L /L?1.0 ?L /L?1.5 ?L /L?2.0 ?L /L),1-MCP treatment(1.5 ?L /L)and then ethylene treatment(100 ?L/L).The observation of the leaves abscission and the cell structure of leaves,the determination of leaf detachment force,endogenous hormone content,related enzyme activities and genes expression,as well as the expression of genes related to ethylene receptors and ethylene signal transduction pathways were used to study the effects of ethylene on Chinese cabbage and its mechanism,and the regulation of 1-MCP to remove Chinese cabbage.And the effect of 1-MCP+ethylene treatment on Chinese cabbage disintegration was studied.The main findings are as follows:(1)Exogenous ethylene treatment can promote the leaves abscission of Chinese cabbage,changed the cell morphology of leaves,and the cell damaged of leaves,the leaf breakstrength decreased significantly,and the ethylene production ability of Chinese cabbage is significantly improved.The ABA content was significantly increased and IAA content was significantly decreased.Exogenous ethylene treatment significantly increased the activities of key enzymes Cx,PG,PME,?-gal and POD,and induced enzyme-related genes Bc CEL,Bc PG,Bc PME,Bc?-gal and Bc POD expression.During the storage of Chinese cabbage,the expression of ethylene receptor and ethylene signal transduction related genes Bc ERS1,Bc ERS2,Bc ETR2 and Bc CTR1 and Bc EIL1,Bc EIL2 and Bc EIL3 were positively regulated by ethylene.It can be seen that exogenous ethylene treatment may regulate the expression of the key genes of the leaves abscission by regulating the genes related to ethylene receptors and ethylene signal transduction pathways to promote the detachment of Chinese cabbage.(2)1-MCP treatment can inhibit the leaves abscission and the decreasing of leaf breakstrength in Chinese cabbage,and 1-MCP treatment significantly reduced the ethylene production and ABA content,and made IAA content significantly increased during the storage period of Chinese cabbage;1-MCP treatment significantly reduced the key enzymes Cx,PG,PME,?-gal and POD of Chinese cabbage,where in 1.5 ?L/L 1-MCP treatment was better than 0.75 ?L/L,1.0 ?L/L,2.0 ?L/L 1-MCP.Moreover,1-MCP treatment inhibited key enzyme genes Bc CEL,Bc PG,Bc PME,Bc?-gal and Bc POD in the leaves of Chinese cabbage and ethylene receptor and ethylene signal transduction related genes Bc ERS1,Bc ERS2,Bc ETR2 and Bc CTR1 and Bc EIL1,Bc EIL2 and Bc EIL3 expression.(3)1-MCP+ethylene treatment can reverse the inhibition of 1-MCP treatment on Chinese cabbage,and the leaf abscess,ethylene production,ABA content and IAA content of Chinese cabbage were restored to the level of the control.At the same time,the inhibitory effect of 1-MCP on the activities of key enzymes Cx,PG,PME,?-gal and POD and related genes Bc CEL,Bc PG,Bc PME,Bc?-gal and Bc POD in Chinese cabbage during storage was reversed,significantly increased by ethylene;the expression levels of ethylene receptor and signal transduction related genes Bc ERS1,Bc ERS2,Bc ETR2 and Bc CTR1 and Bc EIL1,Bc EIL2 and Bc EIL3 were significantly higher than those in 1-MCP treated group,indicating the inhibition of the 1-MCP treatment of Chinese cabbage can be affected by ethylene.