The Function Research Of OsATG7 In Rice Disease Defense

Rice is not only a model plant for basic biology research,but also one of the most important food crops in the world.Pathogens,such as Magnaporthe oryzae and Xoo,can induce rice diseases,which would lead to the yield and quality decline of rice.The innate immune system of plants can resist the invasion of pathogenic bacteria,and plant autophagy may also participate in the defense response to pathogens.Plants have evolved an elaborate innate immune system against the invasion and persecution of pathogens during the long-term evolutionary history.Previous studies proved that plant autophagy may have a role in regulating plant defense responses to pathogens.In this research,the rice mutant atg7 which contains a nonfunctional autophagy related gene OsATG7 was used as the experimental material,and its developmental and disease resistance phenotypes have been identified,a series of vectors for functional research of OsATG7 have been constructed and been used for genetic transformation,rice autophagy pathway and OsATG7 whether and how to participate in the regulation of disease resistance defense responses in rice have been investigated.The results are as follows:1.The rice atg7 homozygous mutant shows shorten height and infertility,has thin stem,few tillers and few roots.Its pollen is fertile,but its anther is not cracked.2.Gibberellin spray can restore the height phenotype of atg7 homozygous mutant.The expression level detection of genes related to GA synthesis pathway led to the speculation that the dwarf defect may be due to the blocking of gibberellin synthesis pathway3.In this study,subcellular localization vector,overexpression and complementary expression vectors of OsATG7 have been constructed,and the fusion protein expression vectors of OATG8a and RFP,ATG8d and RFP also have been constructed.All these vectors have been conducted genetic transformations,and the corresponding T0 generation plants were obtained.The genotypes and target gene expression level of all T0 generation seedplants have been identified,and T1 seeds will be harvest soon.4.After flg22 and chitin treatment,the expression level of resistance related genes OsPBZ1 and OsRac1 in atg7 mutant plants were evaluated.The results showed that the deletion of OsATG7 gene weakened the flg22 induced defense response signal,but enhanced the chitin induced defense response signal of rice,and also enhanced the OsRac1 mediated resistance signal response pathway,which indicated that OsATG7 may be involved in rice PTI immune response.5.When inoculated with Magnaporthe oryzaet at 12h,the increase of H₂O₂ content in atg7 wild type plant was significantly lower than that of the homozygous mutant,while the autophagy was obviously induced in the wild type plants.Therefore,the negative direction of autophagy regulates the content of ROS in the wild plant and the content of H₂O₂ in the wild plants after the pathogen infection at 12h was increasing,but the content of H₂O₂increases.It was quickly downregulated by autophagy,and the relatively low concentration of H₂O₂ could not induce a strong resistance to the disease to restrict the propagation and expansion of Magnaporthe oryzaet in rice leaves.Therefore,the autophagy pathway in rice and the negative regulation of OsATG7 induced HR-PCD in the host cell of Magnaporthe oryzaet were speculated.6.The results showed that both the atg7 homozygous mutant and wild type plants diaplyed strong resistance to Xoo,there is no significant difference between them on resistance.