Screening And Identification Of Rice Small Exocrine Proteins Related To Rice Blast Resistance

Currently,more than half of the world’s population uses rice as its main food,while more than 60% of Chinese population uses rice as its main food.However,rice diseases are important factors that restrict rice yield and quality.The rice blast caused by Magnaporthe oryzae is a destructive fungal disease on rice,causing huge food losses every year,even leading to crop failure,seriously threatening the food security of our country and even the world.At present,chemical control is still the main means of disease prevention and control,but problems such as the lack of efficient pesticides,drug resistance,and potential threats to the environment limit the green and efficient control of rice blast.In the long-term co evolution process between plants and pathogens,there are a large number of potential disease resistance resources in plants,including a class of exocrine proteins that can stimulate plant immunity and resist pathogen infection.Although some current studies have shown that plant small proteins can positively regulate the resistance of plants to bacteria,fungi,and herbivores,and also play an important role in plant growth and development and abiotic stress response,the role of some small proteins,especially small exocrine proteins,in the disease resistance process of rice is still unclear.Previous laboratory studies have found that when rice blast fungus infects rice,a large number of plant secreted proteins are produced in the extracellular space,the frontier battlefield of interaction between the pathogen and rice,suggesting that these proteins may be closely related to the resistance to rice blast fungus infection.Therefore,this thesis focuses on rice exocrine proteins,especially small exocrine proteins,in the extracellular space during the interaction between the pathogen and rice,with the aim of searching for rice resistance factors that can exert immune stimulation and antibacterial functions,creating corresponding transgenic plants,enriching rice resistance resources,and providing important references for achieving green and efficient control of rice blast.The main results are as follows:Using wild type rice blast fungus Guy11 and susceptible rice variety TP309 as experimental materials,73 candidate rice exocrine proteins containing signal peptides with amino acid numbers less than 200 were selected through extracellular space proteomic analysis during the infection stage,and 45 of them were determined to have significant differences in the expression level of coding genes before and after infection(31 upregulated and 14downregulated).Through luminol detection,DAB and NBT staining,and fluorescent probe DCFH-DA analysis,it was found that the small exocrine proteins corresponding to some of the down-regulated coding genes can stimulate the active oxygen species(Os Ssp1,Os Ssp2,Os Ssp3,and Os Ssp4)of plants,and that Os Ssp1,Os Ssp2,and Os Ssp3 can indeed be secreted into the extracellular space of plants.Further,through transgenic methods,overexpression rice lines encoding genes Os SSP1,Os SSP2,and Os SSP3 were selected and found to enhance the immune response and resistance to rice blast in rice without affecting the normal growth and yield of rice.In summary,in this paper,three important exocrine proteins that can stimulate plant immune responses and enhance rice resistance to rice blast were obtained through screening and identification of rice exocrine proteins in the extracellular space of interaction between rice blast fungus and rice,and their overexpression strains were created,verifying their function in enhancing rice resistance without affecting the development and yield of rice itself,It not only enriches the resistance resources of rice,but also provides an important reference for the subsequent development of green and efficient control strategies for rice blast,mainly using plant derived antimicrobial peptides.