De Novo Expression Of Hpa1_10-42 And Silencing Of Innate TaRGA Gene Alter Powdery Mildew Resistance In Wheat

Wheat is worldwide crop,also widely cultivated in China.As the world's population increasing,people are constantly increasing demand for wheat.However,harsh natural environment and the infection of various diseases and insect pests are serious threats to the yield and quality of wheat.Powdery mildew is one of the most important diseases in wheat each year,causing huge losses to the yield of wheat.Our laboratory colleagues have transferred fragment to wheat genome by transgenic technology,obtaining the Hpa1_10-42 transgenic wheat varieties.Our research identified the transgenic wheat we obtained,and verified its resistance to wheat powdery mildew.TaRGA gene is a disease resistant gene cloned by our laboratory colleagues,and in this research we explored its resistance to powdery mildew on the application of BSMV VIGS technology.1.Hpa1_10-42 transgenic wheat enhances resistance to powdery mildewIn this experiment,we found that ectopic expression of Hpa1_10-42 could enhance resistance to powdery mildew.We screened and identified 9 Hpa1_10-42 transgenic lines,and we measured the expression of Hpa1_10-42 on different levels in each transgenic line.When inoculated by powdery mildew,compared with non transgenic lines and other transgenic lines,No.3 and No.39 lines showed obvious resistance to powdery mildew.These results indicate that,ectopic expression of Hpa1_10-42 gene in transgenic lines of wheat can enhance the resistance to powdery mildew.Then we explored the mechanism of resistance of Hpa1_10-42 gene to powdery mildew,finding that the expression of PR genes in No.3 and No.39 lines was significantly higher than that of other transgenic lines and the non transgenic wheat.What's more,the histological observation found that accumulation of callose was significantly higher in No.3 and No.39 lines,and the growth of mycelium was inhibited.The above results indicate that the expression of the Hpa1_10-42 gene can activate defense responses in plants,and then inhibit powdery mildew hyphal growth,enhance the resistance to wheat powdery mildew.2.TaRGA gene silencing by VIGS technology nullifies powdery mildew resistance in the resistant wheat variety Nannong 9918TaRGA gene is a disease resistant gene cloned by our laboratory colleagues by homologous cloning technology,and bioinformatics analysis showed that the protein sequences contain the NB-ARC domain and the LRR repeat sequence,so we speculated that TaRGA gene may be involved in wheat defense response.In our research,we successfully silenced TaRGA gene by BSMV VIGS technology in Nannong 9918,which is a powdery mildew resistant wheat specie.Phenotypic observations found that silenced wheat leaves began to appear white spore,and histological observation showed that a large number of powdery mildew secondary hyphae began to appear in the leaves after virus inoculation.At the same time,we measured the expression of PR gene after TaRGA gene silenced,and we found that the silenced TaRGA gene,PR gene expression was significantly reduced.After treated with SA and H2O2,TaRGA gene expression increased,suggesting that SA and H2O2 can induce the expression of TaRGA gene.These results suggest that TaRGA gene may enhance wheat powdery mildew resistance.Summary remarksThe application of transgenic technology transferred Hpa1_10-42 gene into wheat,which can enhance the resistance to wheat powdery mildew.The application of BSMV VIGS technology can silence TaRGA gene in contemporary generation,finding the gene function according to its phenotypic changes.