Studies On Response Of Abiotic Stress And Regulation Of Capsaicinoid Biosynthetic Gene Expression By CcMYB4a Transcription Factor In Shuan La(capsicum Chinense L.)

Capsaicin,which has a spicy taste,is a unique product of chili peppers and has important nutritional,medicinal,and economic value.MYB transcription factors are a very large family and play regulatory roles in various plant metabolic pathways.In recent years,predecessors have studied the MYB4 transcription factor in various plants.Moreover,an increasing number of MYB transcription factors have been found to be involved in the regulation of capsaicin biosynthesis pathways.Therefore,in this study,the hot pepper with high capsaicin content was taken as the research material,and the characteristics of CcMYB4a gene and protein were analyzed based on gene cloning and bioinformatics methods.The effects of abiotic stress on CcMYB4a gene were studied by using different exogenous material treatment,and the effects of CcMYB4a gene on the capsaicinoid biosynthetic gene network were studied by silencing the CcMYB4a gene using VIGS technology.The main results of the study are as follows:1.The CcMYB4a gene is composed of 750 bases and encodes 249 amino acid residues.The molecular formula of CcMYB4a protein is C₁₂₈₂H₁₉₃₈N₃₆₄O₃₉₄S₁₀,which is a lipid soluble and hydrophilic unstable protein.Upstream cis element prediction revealed the presence of multiple hormone related regulatory elements in the promoter region of the CcMYB4a gene,indicating that CcMYB4a may be influenced by plant hormones.Conservative domain analysis shows that CcMYB4a belongs to the PLN03091 superfamily.PLN03091 is classified as a model that may span multiple domains,and it is the only member of the superfamily cl33633.CcMYB4a exhibits species conservation in structure,but there are also evolutionary differences.The subcellular localization results of Arabidopsis showed that CcMYB4a is located in the nucleus.2.CcMYB4a gene expression was measured under different non Biotic stress.The results showed that CcMYB4a gene in the leaves of pepper seedlings was inhibited by abscisic acid,auxin,methyl jasmonic acid and heat treatment.The CcMYB4a gene in the leaves of pepper seedlings showed a promoting effect under salicylic acid,mannitol,and hydrogen peroxide treatments.The CcMYB4a gene in the roots of pepper seedlings was inhibited by gibberellin,auxin and heat treatment.In summary,the expression level of CcMYB4a varies in different parts of seedlings under the same exogenous stress treatment;The expression level of CcMYB4a varies under different exogenous stress treatments at the same seedling site,and the time of stress response varies under different exogenous stress conditions.3.The CcMYB4a gene was successfully silenced using VIGS technology in both leaf site infection and in vitro fruit infection.After the CcMYB4a gene was silenced by leaf infection,both chlorophyll structure genes and carotenoid structure genes increased to varying degrees,while only the PSY gene showed a decrease.The expression levels of capsaicinoid biosynthetic structural genes KAS,ACL,ACS,and AT3 were significantly increased after silencing of the CcMYB4a gene infected with in vitro fruits.