Identification Of Secreted Elicitors Of Phytophthora Sojae

Living in the nature, plants, above and below ground, face a constant barrage of invading microorganisms, including bacteria, fungi and oomycetes. Plants, unlike mammals, lack mobile defender cells and a somatic adaptive immune system. Instead, they rely on the innate immunity of each cell and on systemic signals emanating from infection sites. The innate immunity of plant consists of two parts. In first part, pathogen-associated molecular patterns (PAMPs orMAMPs) are recognized by PRRs of plant, resulting in PAMP-triggered immunity (PTI). Elicitors or PAMPs (orMAMPs) can simulate communication of signals in plant pathogen interactions, and trigger the plant immune system, which can lead to rapid programmed cell death (hypersensitive response, HR), always with inducing of systemic acquired resistance (SAR) and broad-spectrum resistance in plants. Plants have a second line of defence, in the form of resistance(R) proteins, the products of which directly or indirectly detect effectors (termed avirulence proteins; AVRs), and confer immunity(Effector-triggered immunity-ETI) to pathogens that are successful in suppressing PTI.Nowadays, some Elicitors and PAMPs in oomycetes had been identified, such as transglutaminase, cellulose-binding elicitor lectin (CBEL), Lipid-transfer proteins (elicitins), necrosis-inducing proteins (NLP) and β-Glucans. We hope that we can find more Elicitors or PAMPs in oomycetes to help us to understand mechanisms of PAMPs and to set the stage for prevention of oomycetes. Culture solution of synthesis was used in this experiment to accelerate Phytophthora sojae to secrete more proteins. The acquisition of secreted proteins was completed by ammonium sulfate precipitation, then we dealt with solution of these protein. These proteins were separated and purified by FPLC. we purified a55KD protein (Ps55) with elicitor activity in secreted proteins of Phytophthora sojae. The activity of Ps55was to be identified through injection of tobacco leaves, and the result infer that this protein can lead to hypersensitive response (HR) of tobacco leaves36h after injection. Apart from that, this experiment helped us to set up a system of hunting PAMPs or elicitor in Phytophthora sojae. Elicitor and Pathogen-associated molecular patterns (PAMPs orMAMPs) can simulate communication of signals in plant pathogen interactions, and trigger the plant immune system. Ps55have elicitor activity, but we know little about the funtion of this protein. In this experiment, we got11mass spectras by LC-MS/MS of this protein. After analysis of this resullt, we found that the11peptides belonged to4proteins, named as Ps55-1、 Ps55-2、 Ps55-3and Ps55-4. Structure prediction for proteins sequence using SMART program revealed that Ps55-1、Ps55-2and Ps55-4were similar to the known protein named as cellulase, Ps55-3was similar to the aspartic protease. In this study, we also predicted many putative cellulase and aspartic protease coding genes in the genome of P. sojae according to the sequences and domains. In P. sojae, the transcription profile of putative cellulase and aspartic protease were also performed by RNA-sequencing. These results provide a new study way for analysis function gene, which is crucial to disease control and drug development.