Study On The Mechanism Of Mediator Complex Subunit BnMED16 And Elongator Complex Subunit BnELP4 In The Sclerotinia Sclerotiorum Resistance Of Rape

Sclerotinia stem rot(SSR)is the devastating diseases in rapeseed,which is hard to prevent and control,and causes huge economic losses of oilseed rape production.At present,it is urgent to screen the factors with broad-spectrum resistance and analyze their resistance mechanism,so as to provide new germplasm resources and theoretical basis for genetic improvement and breeding of disease-resistant varieties.Plants will be instructed to change from normal growth and development pathway to defense response signal pathway when they are infected by pathogens,and organisms will undergo a drastic transcriptional reprogram.Two kinds of transcription factors,Mediator complex(MED)and Elongator complex(ELP),are the key factors involved in this process,but the specific resistance mechanism needs to be further studied.On the other hand,it has been found that plant cell wall is not only a structural passive defense barrier.The minor damage to the cell wall or changes in its structural components will lead to the activation of plant disease resistance signal pathways and defense responses.It is rarely reported in crops but only a few studies have been done on the model plant arabidopsis thaliana.In this study,Brassica napus was taken as the main research object,starting from the source of plant immune response,In-depth analysis of the mechanism of plant cell wall resistance and transcription factor-mediated resistance to Sclerotinia sclerotiorum in rape.The results will provide scientific basis and germplasm resources for rape breeding for resistance to SSR.The main results are as follows:1.By analyzing the expression patterns of transcription factor MED family genes and ELP family genes after inoculation with Sclerotinia sclerotiorum,it was found that the expression levels of BnMED16 and BnELP2,BnELP3,BnELP4 genes were significantly induced;2.The BnMED16 overexpression transgenic strain was constructed by transferring the BnMED16 overexpression vector into rapeseed.After inoculation,it was found that the overexpression BnMED16 strain enhanced the expression of defense genes,activated the signal pathways related to disease resistance,and promoted the accumulation of reactive oxygen species.And to remove and induce plant cell wall resistance,thereby improving the resistance to Sclerotinia sclerotiorum;3.Through the point-to-point yeast two-hybrid experiment on BnMED16 and BnMED25,BnMED16 and BnWRKY33,it was found that BnMED16 can interact with BnMED25 and BnWRKY33,and the BiFC experiment further verified its interaction in vivo.It is speculated that BnMED16 interacts with BnMED25 protein,so as to control the activation intensity of the jasmonic acid signal pathway to enhance the resistance of rape to Sclerotinia sclerotiorum;4.By constructing the BnELP4 overexpression vector and transforming it into rapeseed,the BnELP4 overexpression transgenic strain was obtained;after the in vitro leaf inoculation experiment on the strain with obvious increase in expression,it was found that the overexpression of BnELP4 gene can significantly enhance the defense Gene expression,activation of disease resistance signal pathways and promotion of the accumulation and removal of reactive oxygen species enhance the resistance of rapeseed to sclerotinia sclerotiorum;however,the mechanism of BnELP family-mediated antimicrobial sclerotinia disease in rape needs to be further studied.