Research On The Transcriptional Regulatory Network Of The NPR1-mediated Acquired Resistance In Triticeae Crops

Systemic Acquired Resistance(SAR)in plant is established beyond the initial pathogenic infection or is directly induced by treatment with salicylic acid or its functional analogs(SA/INA/BTH).NPR1 protein and WRKY transcription factors are considered the master regulators of SAR.In Triticeae crops of wheat and barley,a SAR-like response,known as Acquired Resistance(AR),can be induced by Pseudomonas syringae pv.tomato DC3000 in the region adjacent to the infiltration area.However,the transcriptional regulatory network of AR and function of the NPR1 gene in these Triticeae species are largely unkown.In the present investigation,we proved that AR induced by P.syringae DC3000 was sufficient to improve wheat resistance to Puccinia triticina(Pt).In our subsequent analysis,barley transgenic line overexpressing wheat wNPR1 gene(Ubi::wNPR1)showed enhanced resistance to Magnaporthe oryzae isolate Guy11,whereas AR to Guy11 was suppressed in a barley transgenic line with knocked-down barley HvNPR1 gene(Ubi::HvNPR1-Kd).We performed RNA-seq to reveal the genes that were differentially expressed among these transgenic lines and the wild-type barley plants during the AR.Several PR and BTH-induced(BCI)genes were designated as downstream genes of NPR1.The expression of few WRKYs was significantly associated with NPR1 expression during the AR events.The transient expression of three WRKY genes,including HvWRKY6,HvWRKY40,and HvWRKY70,in wheat leaves by Agrobacterium-mediated infiltration enhanced the resistance to Pt.In conclusion,a profile of genes associated with NPR1-mediated AR in barley was drafted and its great potentials in improvement of wheat resistance were clarified.Differentially expressed genes,as well as the crucial WRKY genes identified in the current study,will provide valuable clues and novel breeding resoures for the genetic modification of wheat.