| Wheat stripe rust which caused by Puccinia striiformis f.sp.tritici(Pst)is very serious fungal disease,resulting in great loss of wheat yield and compromising wheat quality,so that poses a serious threat to wheat production.Cultivation of disease-resistant wheat varieties is the main strategy to prevent Pst at present,but it may not be effective for long-term due to the rapid diversification of Pst.So it is imperative to reveal the pathogenesis of Pst and then construct new durable resistance systerm.Pst which causes extensive loss of wheat production belongs to obligate biotrophic fungi.During infection,Pst develops a specialized infection structure-haustorium,from which bunches of secreted effectors are released to host cells to regulate a wide range of plant physiological process.Identification and characterization of haustoria specific effectors will be helpful to reveal the pathogenesis of Pst,but little is known about the effectors of Pst at present.Large sets of secreted proteins were obtained through bioinformatic prediction from the accomplished Pst haustoria transcriptome in our lab.In this study,65 predicted haustoria specific secreted proteins were tested and 27 candidate effectors were identified to be able to suppress PCD induced by BAX using Agrobacterium-mediated transient expression in tobaccoes.Then,taken advantage of bacteria type three secretion system(TTSS)to deliver Pst effectors into wheat cells,12 effectors were observed to block PAMP triggered immunity(PTI)-associated callose deposition in wheat cells,and there were 4 effectors could significantly suppress the ROS accumulation and slightly reduce necrotic areas which are both typical characteristics of effectors triggered immunity(ETI).In the meantime,we found that 7 effectors could increase Pst biomass at late infection stage(120h).Our results proved that Pst haustoria is indeed rich in virulence effctors,which could suppress host immunity and enhance Pst virulence. |
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