| Rice sheath blight(Sh B)is one of the main rice diseases in China.In recent years,this disease has been widespread in rice-growing regions of China,and has surpassed the rice blast to become the primary disease in some areas.Clarifying the pathogenic mechanism of Sh B,perfecting the interacting regulatory network between rice and Sh B,and developing green prevention and control technology of Sh B are very important for rice production and quality safety in China.Based on the pathogenicity and host interaction regulation mechanism of Sh B,this study had analyzed the potential pathogenic mechanism of Sh B by comparing Rhizoctonia solani AG1-IA and R.oryzae-sativa AG-Bb,explored the regulatory factors in the interaction between rice and Sh B,and clarified the function of the R.oryzae-sativa AG-Bb to induce resistance to Sh B.The main research results are as follows:1.The pathogenicity of AG-Bb and AG1-IA showed that the AG1-IA showed strong pathogenicity,while the AG-Bb showed low or no pathogenicity.The PG,PMG and Cx activities of AG1-IA were significantly higher than those of AG-Bb.In the process of inoculation,the expressions of PG2 and Cx5 genes in AG1-IA were firstly increased and then decreased,while the expression levels of AG-Bb were not significantly changed.The toxin production and pathogenicity of AG1-IA were significantly higher than that of AG-Bb.The sclerotia exudates of AG1-IA had pathogenicity,and pectin lyase might be the main pathogenic factor of the sclerotia exudates of AG1-IA.2.High quality genome of R.oryzae-sativa AG-Bb was obtained by Survey sequencing and Pac Bio sequencing technology,and the genomic differences between AG-Bb and AG1-IA were compared.The phylogenetic results showed that the genetic distance between binucleate Rhizoctonia and uninucleate Rhizoctonia was relatively close.The different anastomosis groups of multinucleate Rhizoctonia were divided into several groups.The genetic distance between the AG1 anastomosis groups of multinucleate Rhizoctonia and binucleate Rhizoctonia and uninucleate Rhizoctonia was relatively close.According to the protein domain annotation,the specific secreted proteins of AG-Bb and AG1-IA were enriched in the subtilis protein families and pectin lyase families,respectively.In the carbohydrate enzyme gene annotation,the number of carbohydrate enzyme genes in AG1-IA was significantly higher than that in AG-Bb,and the difference was greatest in glycosylhydrolase family and glycosyltransferase family.In secondary metabolites genes annotation,nrps and terpene proteins accounted for the largest proportion in AG-Bb and AG1-IA.3.Transcriptome and proteome sequencing techniques were used to analyze the differences in immune response inoculated by AG-Bb and AG1-IA,both of which could induce the expression of defense genes PBZ1 and PR1 b in rice.In the AG-Bb anastomosis groups,GO and KEGG pathways were significantly enriched inĪ³-glutamyl cyclitransferase activity,photoreactive repair,plant-pathogen interaction,glutathione metabolism,phenylpropane metabolism,cell wall formation and chloroplast function.In AG1-IA anastomosis groups,the concentrations of GO and KEGG pathways were t RNA binding,mitochondrial regulation,dterpene biosynthesis,phenylpropane metabolism,glutathione metabolism and chloroplast function.The differentially expressed genes of Os Psb28,Os Psb Y,Os MPK4 and Os EBF between AG-Bb and AG1-IA might be the key targets of pathogen infection.4.According to transcriptome data and q PCR analysis,Expression of Os ZF8 gene responded to the infection of Sh B.The identification results of resistance to Sh B in mutant and wild-type plants indicate that Os ZF8 gene negatively regulated rice resistance to Sh B.Under the stress of the pathogen of Sh B,the expression levels of defense-related genes in the mutant and wild-type plants did not change significantly or the expression pattern was inconsistent with the resistance levels.It was speculated that Os ZF8 might regulate resistance to Sh B not mainly through transcription level,but through protein level in rice.The Os ZF8 interacting protein PRB1 was screened by Y2 H and Bi FC.Os ZF8 effectively inhibited PRB1-induced tobacco cell death.Molecular docking results showed that Prb1 and Os ZF8 protein had stronger binding effect.Compared with PRB1,the binding ability of OSZF8-PRB1 protein complex to ergosterol was significantly reduced.5.Inoculation of mycelium and sclerotia exudates of AG-Bb anastomosis groups could significantly improve rice resistance to Sh B,but had no direct inhibition on AG1-IA anastomosis groups.The inducing effect of plant disease resistance by inoculation treatment of sclerotia exudates was earlier than that of mycelium inoculation treatment,but was equivalent at the later stage.Inoculation with mycelium and sclerotia exudates of AG-Bb could improve the activities of POD,CAT,SOD,PPO,PAL and GSH defense enzymes in rice leaves,and induced the expression of PAL1,PR1 b,PR10 and PBZ1 resistance related genes.In conclusion,this study confirmed that the activity and related gene expression of cell wall degrading enzyme,toxin production and sclerotia exudates pathogenicity were the main pathogenic factors of the pathogen of Sh B.The expansion of glycosylhydrolase families and glycosyltransferase gene families is the main molecular basis for the pathogenesis of the pathogen of Sh B.Both AG-Bb and AG1-IA anastomosis groups can induce immune response in rice.Os ZF8 negatively regulated resistance to Sh B by binding to PRB1 protein and inhibiting the binding ability of PRB1 protein to ergosterol in rice.The function of AG-Bb to induce resistance to Sh B was clarified.The results can provide new insights and research directions for further revealing the pathogenic factors,the regulation mode of host interaction and the green control of Sh B. |
