Analysis And Application Of Immune-inducing Activity Of Fusarium Graminearum Effector Fg62 And Soybean Elicitor Peptide GmPep3

Soybean root rot is one of the important diseases in soybean production,and Fusarium graminearum is one of the main pathogens causing the disease.At the same time,it can also harm wheat,barley,rice and many other kinds of crops.It can also cause different crop diseases such as head blight and ear rot.The use of chemical pesticides and cultivation of disease-resistant varieties are the main prevention and control measures for the prevention and control of crop diseases in agricultural production.However,the problem of pesticide residues has become more serious due to the unreasonable use of chemical pesticides.In addition,it has also caused serious consequences such as increased resistance to pathogens and loss of resistance to disease-resistant varieties.Therefore,it is urgent to develop efficient and environmentally friendly disease prevention and control measures to solve the above problems.When pathogens attack plants,pathogens will also manipulate the host’s defense behavior through effectors,and plants will activate their own immune responses by recognizing these effectors or secreting elicitor peptides and other substances.Therefore,the identification and analysis of pathogen effector functions and plant elicitor peptides are of great significance for exploring the interaction mechanism between plants and pathogens.On the other hand,due to the existence of short delivery time,easy degradation,short duration and other problems of traditional protein-based biological pesticides,it is necessary to develop a system that can stably deliver decoy proteins.In addition,certain Bacillus subtilis strains are not only potential biocontrol agents and plant growth promoters,but also an efficient platform for exogenous protein secretion.The use of B.subtilis system to produce the identified plant immune elicitors is helpful for the development of new green and safe biological pesticides.The purpose of this study is to analyze Fg62 identified and screened in the culture filtrate of F.graminearum,and to further study its function of inducing plant immune activity.At the same time,further research is carried out on the immune inducing activity of soybean elicitor peptide GmPep3.Finally,the two were transferred to B.subtilis to study their disease resistance.The specific research content is as follows:1.The function analysis and application research of Fg62 in inducing plant immune activity.Based on the analysis of the effectors that can induce plant cell death identified in the filtrate of the F.graminearum culture in the preliminary laboratory research,a large amount of crude protein of the remaining four effectors was obtained through prokaryotic expression.Soybeans treated with crude protein seeds were grown in the pots of mixed F.graminearum and Phytophthora sojae,Fg62 crude protein was found to induce soybean resistance to different pathogens.Fg62 was transiently expressed in tobacco and found that it can induce cell death in tobacco leaves,and its ability to induce cell death depends on the N-terminal signal peptide.The pure Fg62 protein was obtained by prokaryotic expression and treated with tobacco and found that Fg62 can cause the up-regulated expression of multiple plant defense-related genes.In addition,treatment of tobacco leaves with Fg62 pure protein and inoculation with Phytophthora capsici found that it can enhance tobacco resistance to P.capsici.Soybeans treated with Fg62 seeds were planted in pots containing F.graminearum and P.sojae.It was found that Fg62 pure protein can induce soybean resistance to different pathogens.Furthermore,the Fg62 encoding gene is transferred into B.subtilis,and the soybean is treated with the transgenic Bacillus liquid for root irrigation,which can significantly improve the resistance of soybean to P.sojae.In summary,Fg62 has the function of inducing plant immunity,and the recombinant B.subtilis transferred into Fg62 has the potential to develop into a biocontrol agent.2.The function analysis and application research of GmPep3 in inducing plant immune activityGmPep3 is a conserved immune elicitor peptide in soybeans.In order to verify its immune-inducing activity,the GmPep3 synthetic peptide solution was used to spray tobacco leaves and found that GmPep3 can up regulate multiple defense-related genes in tobacco.In addition,the GmPep3 peptide was used to treat tobacco leaves and inoculated with P.capsici,and found that it can enhance tobacco resistance to P.capsici.Soybean seeds were treated with GmPep3 and planted in pots inoculated with F.graminearum and P.sojae.It was found that GmPep3 could improve soybean resistance to different pathogens.Further use of the B.subtilis with GmPep3 encoding gene to irrigate soybeans can significantly improve soybean resistance to P.sojae.In summary,GmPep3 can induce plant immunity,and the recombinant B.subtilis transferred into GmPep3 has the potential to develop into a biocontrol agent.