Functional Analysis And Targets Identification Of Effector Pst19032 From Puccinia Striiformis F.sp.tritici

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),has done serious harm to wheat growing worldwide.Due to the lack of reliable genetic transformation technology,pathogenic mechanism of Pst key genes is poorly understood.Effectors,specificly secreted by the pathogen,contribute to the pathogen infection and can interfere with or damage the host plant physiological metabolism and defense reaction to increase susceptibility,which play very important roles in the pathogenecity.According to the "gene-to-gene hypothesis",when the R gene could be recognized by the corresponding avirulence effector,their interaction will transmit the resistant signals to the downstream to raise intensly immune response.At that time,these identified effectors play the anvirulence function.Analyzing the function and identifing the host targets of effectors can further clarify their exact roles and reveal the molecular mechanism of wheat stripe rust fugus.In this study,Pst19032 containing a nuclear localization signal was selected for further study based on the previous research.The main results are as follows:(1)The Pst19032 gene was conserved among the rust species and different Pst isolates;(2)qRT-PCR analyses showed that the expression of Pst19032 gene had two peaks in the middle and late stages during Pst infection,which indicated that its function was diverse;(3)The Pst19032 located in the nucleus by subcellular localization in the wheat protoplast;(4)The Pst19032 could inhibit the PCD induced by BAX using the agrobacterium-mediated transient expression in Nicotiana benthamiana,indicating the effector had a virulence function.But the accumulation of callose were increased when Pst19032 was overexpressed in wheat by the type III secretion system,which demostrated that Pst19032 play the avirulence function to trigger host PTI immunity;(5)The pathogen biomass was not significantly changed,but the susceptibility of host plant was slightly enhanced,the number of haustorium and area of hyphae were increased after 48 hpi when Pst19032 was silenced by HIGS.(6)The potential interacting targets of Pst19032 effector were Pst19131,Pst19331,Ta19202,Ta19144,Ta19351,Ta19231,Ta19602 and Ta23184 by yeast two-hybrid system;(7)the interactions of Pst19032 and Ta19231,Ta19602,Ta23184 were confirmed by yeastsystem and bimolecular fluorescence technique.