Functional Analysis Of StLRPK1in PTI Against Phytophthora Infestans In Potato

Plant innate immune system is mainly composed by the PTI and ETI, which are triggered by Pathogen Associated Molecular Patterns (PAMPs) and Effectors respectively. PTI, as the first line of defense against pathogen invasion, is an important mechanism for the resistance to the microorganisms infection, has a broad spectrum and long-lasting features. The research on the mechanisms of PTI can provide important theoretical and application value to guide plants breeding with broad spectrum and long-lasting resistance. StLRPKl, cloned by our lab in the early research, is a potato receptor-like kinase gene. Subcellular localization of GFP fusion proteins display its location in the cell membrane; To the over-expression and RNAi transgenic lines, P.infestans inoculation results implicted that StLRPKl plays an important role in broad-spectrum resistance to the late blight.In this study, though StLRPKl transgenic lines identification of late blight resistance to explore its mechanism in potato late blight resistance. The main results are as follows:1. Over-expression and RNAi transgenic lines were identified by qRT-PCR, which eight over-expression and three RNAi transgenic lines effect are abvious. The highest silencing efficiency of the RNAi transgenic lines was up to69.3%. Late blight inoculation experiments using four different physiological races of P. infestans. The lesion and mycelial growth results showed that compared to the control, the over-expression transgenic plants showed more resistance and StLRPK1-RNAi transgenic plants showed more susceptible to P.infestance. It reveals that as a positive regulatory factor, StLRPK1plays an important role against P. infestans.2. Hydrogen peroxide accumulation, cell death and callose deposition at the inoculation point were observed at the histochemical level. Compared to the control, over-expression lines near the inoculation point of hydrogen peroxide, callose deposition are more serious phenomenon of dead cells are lighter, while RNAi transgenic lines near the inoculation point of hydrogen peroxide, callose deposition of are light, phenomenon of dead cells are serious. These results suggest that StLRPKl gene promotes the accumulation of hydrogen peroxide, callose deposition and restricts pathogen growth, inspired basic defense response in potato. 3. Resistance related gene expression analysis showed that without inoculation over-expressing StLRPKl transgenic lines can make resistance related gene StPR1, StPR10a, StNPR1up-regulated expression, thus it can play an important role in the early against P. infestans. Inoculation identification, histochemistry and resistance related gene expression analysis showed that StLRPK1involved in the potato basic defense response (PTI) and plays an important role in Broad-spectrum resistance against P. infestans.4. GUS activity assay showed StLRPK1gene promoter can be induced by ETH, SA, MeJA, NaCl. Under150mM/L NaCl salt stress condition, the growth of over-expression and RNAi transgenic seedings lines were both inhibited, Statistical results of root length, fresh weight showed no significant difference among those transgenic lines. Statistical results of stem length show two OE-lines and three RNAi-lines compare with wt have significant difference. It shows that StLRPK1can improve plant salt tolerance to some extent.