Role Of CaWRKY20 In Response To Ralstonia Solanacearum Infection And High Temperature Stress In Pepper

Pepper(Capsicum annuum)is one of the most important crops in China,which has important economic and edible value,but it is susceptible to infection by Ralstonia solanacearum and high temperature stress during its growth process,which has a serious impact on the quality and yield of pepper.Therefore,studying the disease resistance and stress resistance mechanism of pepper is one of the key factors to improve the quality and yield of pepper.In this study,Ca WRKY20,a member of the WRKY family of peppers,was cloned,and its structure and function were preliminary analyzed.The main results are as follows:(1)A c DNA with a total length of 1821 bp was cloned from the leaves of pepper.It contains two conserved WRKY domains and has high homology with the amino acid sequences of potato,tobacco,tomato,grape and Arabidopsis,which are 73.08%,69.22%,58.35%,54.85% and 49.58%,respectively.It is named Ca WRKY20,which belongs to the ? category of WRKY family members.(2)Using the constructed 35S::Ca WRKY20-GFP fusion expression vector,transiently overexpressed in tobacco leaves,it was found that the protein encoded by the Ca WRKY20 gene is located in the nucleus,indicating that the gene acts as a transcription factor in the nucleus.Using q RT-RCR,the expression patterns of Ca WRKY20 after exposure to Ralstonia solanacearum at normal temperature,high temperature,and spraying with exogenous hormones Me JA,ETH,and SA were found.The results showed that the gene was up-regulated in Ralstonia solanacearum at normal temperature and under high temperature conditions.It is also induced by the expression of exogenous hormones Me JA,ETH and SA;it is revealed that Ca WRKY20 may play a certain regulatory role in pepper response to biotic and abiotic stress.(3)Transient overexpression of Ca WRKY20 on pepper leaves can significantly cause cell death and accumulation of H2O2,and induce the up-regulation of immune-related marker genes Ca NPR1,Ca DEF1 and Ca ACO and heat-resistant marker genes Ca Hsf A2 and Ca HSP24.(4)The silencing of Ca WRKY20 mediated by virus-induced gene silencing significantly reduced the resistance of pepper plants to Ralstonia solanacearum and the tolerance to high temperature;the overexpression tobacco Ca WRKY20 was obtained by Agrobacterium-mediated genetic transformation Plants,and using T2 transgenic tobacco plants for experiments,it was found that overexpression of Ca WRKY20 can significantly improve the resistance of tobacco to Ralstonia solanacearum and tolerance to high temperature,which showes that Ca WRKY20 as a positive regulator,played an important role in the treatment of Ralstonia solanacearum at normal temperature and high temperature.In summary,the results of this study indicate that Ca WRKY20 plays a positive regulatory role in the process of pepper response to Ralstonia solanacearum infection and high temperature stress.The results of this study have initially clarified the structure and function of Ca WRKY20 and enriched WRKY to a certain extent.The functional study of transcription factors is helpful for the analysis of the mechanism of pepper in response to Ralstonia solanacearum infection and high temperature stress,and provides a certain theoretical basis for breeding resistant pepper varieties.