Functional Analysis Of Maize Disease Resistance Gene ZmMYC2

As an important food and cash crop,the growth and development of maize are often affected by various pathogens,resulting in the decrease of yield and quality of maize.Therefore,it is of great theoretical and practical significance for maize production and selection of good maize varieties to dig out disease-related genes of maize and analyze their functionsJasmonic acid（JA）,as an important plant hormone,is widely involved in plant growth and development and biological stress regulation.MYC2 belongs to the bHLH-like transcription factor,and as a core regulatory factor in the JA signaling pathway,it has been reported to be involved in plant growth,development and biological stress in several species.However,the function of the MYC2 gene in maize is unclear.In this study,the functions of arabidopsis thaliana were studied by constructing overexpressed mutant replenishment lines and overexpressed rice lines.The results are as follows:1.Sequence analysis revealed that the ZmMYC2 CDS sequence was 2116 bp and encodes 705 amino acids.Alignment with homologous sequences from other species revealed multiple highly conserved functional domains,namely JAZ interaction domain（JID）,basic-helix-loophelix domain（bHLH）,and leucine zipper（Zip）domains.2.Analysis of tissue expression patterns showed that ZmMYC2 was expressed in all tissues of maize,and the highest expression was found in leaves and bracts.Analysis of induced expression patterns showed that ZmMYC2 was induced by bacterial pathogens and JA.3.Transient expression analysis of maize protoplast showed that ZmMYC2 was located in the nucleus.4.After inoculation with DC3000（Psedumonas syringae pv.tomato DC3000）,ZmMYC2 overexpressing plants had significantly less H₂O₂ accumulation in leaves than wild-type,mutant and replenishment lines.The content of leaf bacteria and the number of dead cells were significantly more,and ZmMYC2 decreased plant resistance to pathogens.5.After co-treatment with JA and pst DC3000,the incidence of ZmMYC2 overexpressing plants was significantly reduced,and onset was delayed by about 2 days.Compared with the single pst DC3000 treatment,the difference between the overexpressing plants and the wild type was reduced.In addition,the over-expression of plant cells and the expression of JA pathway-related genes after the treatment of pathogens increased significantly,while the expression of genes related to defense of pathogens decreased significantly.Explain that ZmMYC2 can reduce the resistance of plants to pathogenic bacteria through JA pathway6.Under JA treatment,the root length of the Arabidopsis replenishment line was shorter than that of the mutant,and was similar to that of the wild type.The overexpressed line had the shortest root length.May increase plant sensitivity to JA.7.After inoculation with Xoo（Xanthomonas oryzae pv.oryzae,Xoo）,the incidence of rice over-expressing strains was more severe than that of wild type,indicating that ZmMYC2 is also related to disease resistance in rice.8.Yeast two-hybrid results show that ZmMYC2 protein can bind to ZmJAZ1 and ZmJAZ3,indicating that ZmMYC2 can function in combination with key JA pathway factors in maize.