Screening Of Phytophthora Sojae RXLR Effectors And Functional Study Of Avh238

Phytophthora sojae is anaggressive pathogen that is able to infect and kill soybean plants throughout much of the growing season and leads to annual soybean production losses around the world with the worth of over one billion. P. sojae is one of the pathogenic oomycetes which are classified in the kingdom Protoctista and are related to heterokont, biflagellate, golden-brown alage while fungi from a separate kingdom and are evolutionarily related animals. The evolution distance made Phytophthora a specific plant infection mechanism. We functional analysed RXLR effectors genes of P. sojae. Among the screened effectors,, Avh238, which could induce hypersensitive cell death in N. benthamiana was given a detailed structure and functional analysised.Effector proteins secreted by oomycete pathogens have been inferred to suppression plant disease resistance. Phytophthora sojae deliver about 351 RXLR effectors proteins into plant cells during infection. These proteins may be required for virulence. To identify which of the RXLR-dEER effectors that manipulate plant processes, high-throughput functional expression assays in Nicotiana benthamiana were performed on 32 candidate RXLR-dEER effectors using PVX-based functionalassays. This led to the discovery of 13 effectors can block programmed cell death by mouse pro-apoptosis protein Bax induced in N. benthamiana; and other 10 RXLR-dEER effectors can trigger cell death in N. benthamiana. Our research showed that RXLR effectors with different functions, some may be suppress but others can induce defense response.Using agroinfection with a binary Potato virus X vector, we showed that Avh238 induces cell death in N. benthamiana. Further characterization of the Avh238 gene indicated that induced Pi? gene expression in N. benthamiana.K novel Avirulence Homolog Genes Avh238 carries a signal peptide followed by a conserved RXLR-dEER motif at N-teminal that is functionally required for these effectors host cell-targeting into host cytoplasm. The primary structure and cDNA sequence of this novel necrosis induced protein was determined, and BLAST searches of Swiss-Prot, EMBL, and GenBank data banks showed that Avh238 shared no significant homology with other known protein. Structure-function experiments indicated that the C-terminal region of Avh238, which excludes the RXLR region, is sufficient for trigger cell death.RT-PCR and microarray analysis showed that Avh238 up-regulated in cyst germination or during early stage soybean infection. Indicated that it is may be very important for transition from biotrophy to necrotrophy in the infection process. Overexpression of Avh238 Confers decreased Virulence on Soybean, this suggested Avh238 play a elicitor role in plant cell.