Analysis Of Disease Resistance Function Of Maize ZmRAR1 Gene

Plant production is affected by various pests,insects and weeds,which will not only seriously affect the yield of crops,but also seriously damage the quality of crops.Exploring the potential resistance genes of plants is significant to improve crop yield.In our previous study,weused bioinformatics analysis to screen the candidate resistance gene ZmRAR1disease,and successfully overexpressed ZmRAR1 in Arabidopsis and Oryza sativa by Agrobacterium-mediated transformation,and obtained T5 ZmRAR1-overexpressing Arabidopsis and T2 ZmRAR1-overexpressing Oryza sativa.On this basis,a series of disease resistance tests were carried out on ZmRAR1 transgenic Arabidopsis and Oryza sativa,and the results were as follows:1.The phylogenetic tree of RAR1 protein family in maize,rice,Arabidopsis,barley,wheat and columba was constructed,and the RAR1 protein family was divided into three subfamilies according to the phylogenetic tree branch,among which the ZmRAR1（Zm00001d016716）gene belonged to subfamily II.and was the closest genetic distance to Hv RAR0-1（AAO18080.1）gene in barley,with the highest homology.2.Tissue expression and induced expression pattern analysis showed that ZmRAR1 gene was expressed in different tissue of maize,and its expressions in pollen,anthers and stems were higher.After the maize was treated with Pseudomonas syringae pv.tomato DC3000（Pst）,Sclerotinia sclerotiorum and exogenous hormones SA,JA and ET,the ZmRAR1 gene was expressed to varying degrees.3.When ZmRAR1-overexpressing Arabidopsis was infected by Pst DC3000,the H₂O₂content in the plants rapidly accumulated,cells died programmatically,and the bacteria count decreased.At 24 h after infection with Pst DC3000,the expression levels of PAD4,EDS1,synthetic genes in SA signaling pathway,and PR1 and PR2 which were signaling genes in SA pathway increased,and the SA content in ZmRAR1-overexpressing increased,when compared to the negative controls.Furthermore,the ZmRAR1-overexpressing Arabidopsis were pretreated with salicylic acid inhibitor（ABT）for 24 h,then inoculated with the Pst DC3000,we found the the ZmRAR1-overexpressing Arabidopsis lost their resistance to Pst DC3000,indicating that the overexpression of ZmRAR1 in Arabidopsis could activate the SA signaling pathway and enhance the disease resistance of plants to Pst DC3000.4.When ZmRAR1-overexpressing Arabidopsis was infected with S.sclerotiorum,the H₂O₂ content in plants reduced,the programmed death of cellsdecreased,and the diameter of plaque was smaller.At the 6thh after the infected with S.sclerotiorum,the expression levels of PDF1.2 and ORA59,which were in the JA signaling pathway,,were up-regulated in transgenic plants,and the JA content in ZmRAR1-overexpressingincreased.Subsequently,after being treated with JA inhibitor DIECA,the resistance of the ZmRAR1-overexpressing lines to S.scrotiorum was suppressed,indicating that the overexpression of ZmRAR1 in Arabidopsis could activate the JA signaling pathway and enhance plant resistance to S.sclerotiorum.5.When ZmRAR1-overexpressingrice was infected by the Xanthomonas oryzae pv.oryzicola,the H₂O₂ content accumulated,and the diameters of disease spots were smaller than wild plants.At 72 h after inoculation with the Xanthomonas oryzae pv.oryzicola,compared with thewild ZH11,the expression levels of PR1 and PR2 were up-regulated,and the expression level of SWEET encoding sugar transporter in ZmRAR1-overexpressing were down-regulated.It was shown that the overexpression of ZmRAR1 in rice could activate the SA signaling pathway and improve the disease resistance of plants to Xanthomonas oryzae pv.oryzicola.