Study On The Function Of Powdery Mildew Resistance Of Transcription Factor MdbHLH093 In Apple

As one of the most widely cultivated fruits in the world,the apple(Malus domestica)has great food value,nutritional value and economic value.But in the process of cultivation and production,powdery mildew one of the most common diseases,which seriously affects the yield and quality of apple.This study screened the significantly upregulated gene Mdb HLH093 responsive to apple powdery mildew stress from previous transcriptome data,and explored its regulatory function on apple powdery mildew through heterologous transformation of Arabidopsis and transient transformation of apple leaves.In addition,Y2 H,Bi FC and Split-Luc assay were used to identify the interacting proteins,which provide a theoretical research for screening disease resistance genes,exploring disease resistance mechanism and improving regulatory network.The main research results are as follows:1.Mdb HLH093 sequence was cloned from ’Gala’ c DNA with an open reading frame of1095 bp,encoding 364 amino acids and containing an HLH domain,which was located on chromosome 15 of apple.Phylogenetic tree results showed that Mdb HLH093 was closely related to pear Ppb HLH93.Mdb HLH093 can respond to the induction of powdery mildew.The expression level of Mdb HLH093 is the highest in leaves,and it has the transcriptional self-activation activity.2.The overexpression vector Mdb HLH093 was constructed for allogeneic transformation of Arabidopsis thaliana,and the disease resistance of the transgenic strains was analyzed.The results showed that compared with the wild-type plants,the disease degree of the three transgenic strains was significantly lower,and the number of conidia was less.The results of histochemical staining showed that the incidence area of transgenic Arabidopsis thaliana was small,the accumulation of reactive oxygen species was increased,and the growth and development of mycelium were inhibited.The expression analysis of genes related to SA signaling pathway showed that the expressions of At EDS1,At ICS1,At PR2,At PR5 were significantly higher than those of the wild type after overexpression of Mdb HLH093.It was preliminarily confirmed that Mdb HLH093 had the function of enhancing powdery mildew resistance in plants.3.The disease resistance function of Mdb HLH093 was further verified by instantaneous transformation experiment.Transient overexpression of Mdb HLH093 resulted in less disease,fewer spore count,inhibited growth of mycelium and enhanced transcription of genes related to SA pathway.Instantaneous silences of Mdb HLH093 made the disease more severe in leaves,the number of spores increased,the growth of mycelium was vigorous,and the transcription level of genes related to SA pathway was inhibited.4.Interaction protein identification.The interaction between Mdb HLH093 and Md MYB116 was verified by Y2 H,Bi FC and Split-Luc assay.In summary,a model was proposed for the regulation of apple powdery mildew resistance by transcription factor Mdb HLH093: when the powdery mildew bacteria were introduced,Mdb HLH093 interacts with resistance protein Md MYB116 to synergically enhance the expression of genes related to SA signaling pathway and increase the accumulation of hydrogen peroxide to improve plant resistance to powdery mildew.