Study On The Mechanism Of Secreted Protein Fp00392 In Fusarium Pseudograminis To Stimulate Plant Immune Response

Wheat is one of important grain crops in China,and its production security is related to the national economy and people’s livelihood.Wheat crown rot is an important soil-borne disease occurring frequently in wheat production.In recent years,it has spread rapidly in our country,which not only causes yield loss,but also has the potential threat of mycotoxin pollution.At present,there are no effective varieties with high resistance to crown rot,so this disease poses a potential serious threat to the production of wheat,which makes it very important to study the pathogenic mechanism of pathogen causing wheat crown rot and the interaction mechanism between wheat and pathogen.In the interaction of pathogen and plant,the pattern recognition receptors on the surface of plant cells can identify pathogenassociated molecular patterns(PAMPs)of pathogen,so as to induce the plant to produce an immune response against the pathogen infection.PAMPs are widely found in microorganisms and their conserved structure plays an important role in their growth and development.To study the mechanism of pathogen-associated molecular patterns and modify its receptors is conducive to obtaining more broad spectrum and efficient resistance varieties.However,there are few reports on the research of PAMPs from Fusarium pseudograminis,which is the dominant pathogen triggering wheat crown rot.In the study,we randomly selected 20 secreted proteins based on the genome sequencing results of F.pseudograminis,and screened the functional factor by the screening method mediated by PVX virus.We found that expression of a secreted protein Fp00392 could cause restriction on tobacco growth and development.In addition,the secreted protein Fp00392 from F.pseudograminae can cause cell death after transient expression in tobacco,suggesting that it may be a toxic protein with the function of PAMPs.Then,through a series of experiments and biochemical techniques,such as expression and purificationsystem of protein,q RT-PCR,transient overexpression in tobacco,chemical histocytology staining,the mechanism of cell death induced by Fp00392 was further explored.The main results were obtained as follows:(1)Sequence analysis of Fp00392 showed that the protein was consisted of 147 amino acids.The N-terminal of Fp00392 contained a signal peptide region consisting of 19 amino acids,and the full protein of Fp00392 did not contain known conserved functional domains and transmembrane domains,which indicated that Fp00392 was a typical effector protein.(2)Transient overexpression in tobacco showed that the transient overexpression of Fp00392 containing signal peptide accelerated the necrosis of tobacco cells,indicating that the signal peptide of Fp00392 was very important for the induction of cell necrosis response.These results suggested that Fp00392 is secreted outside the plant cell to function.(3)Fp00392 protein can induce cell death in tobacco,soybean and Arabidopsis,suggesting that it can induce cell death in a variety of plants.(4)Injection of Fp00392 protein induced ROS burst and callose accumulation in tobacco leaves,and triggered up-regulated expression of genes related to defense response,hormone signaling pathways and PTI response.In conclusion,we can speculate that Fp00392 was a PAMP.