Signaling Pathway Of Xa7to Resist Bacterial Blight In Rice

Bacterial blight is one kind of bacterial disease caused by Xanthomonas oryzae pv. Oryzae(Xoo)and the use of bacterial blight resistance genes can effectively control the disease. Xa7of rice is a do minant gene with a broad-spectrum resistance to Xoo interacting with avrXa7. In order to study the signaling pathway of disease resistance mediated by Xa7, we analyzed the expression level of genes of IRBB7(containing Xa7) and IR24(not containing Xa7) at24h and48h after infecting with PXO86by micro array. We found there were883genes differentially expressed in IRBB7and3055genes in IR24.207differentially expressed genes only in IRBB7at24h after infecting PXO86when genes began to express differently, based on gene function annotation, will be divided into pathogenesis-related factor, transcription factors, signal transduction, basic metabolism and metabolic basis of unknown function category. A gene unkown function(Os03g0853200) detected by RT-PCR and Real time-PCR is strongly induced expressed in Xa7disease resistance pathway while not induced in Xa21disease resistance pathway. Besides, this gene expressed very low(except in root) in rice without infecting with pathogens and will induced rapidly in rice leaf after infecting with pathogens. These results showed that this gene may be regulated specially by Xa7. Os03g0853200is a gene encoding tetraspanin with four transmembrane domains, homologous with CD9/CD37/CD63antigen family protein of animals, the protein, at the same branch of genetic evolution tree with Tetraspanin3(TET3) of arabidopsis, was named as OsTET3. By PCR, we coloned OsTET3and its promoter from IRBB7and IR24, respectively, and found that there are no difference of sequence in both rice. We contructed an overexpression vector pCAMBIA1300-Pro35s::OsTET3, transformed into susceptible rice Zhonghua11by Agrobacterium infection and obtained transgenic lines. Simultaneously, we constructed an expression vector pCAMBIA1300-Pro35S::OsTET3:eGFP transient expressed in N.benthamiana by Agrobacterium infection, and observed fluorescence on cell membrane emitted by reporter gene eGFP by confocal microscope, indicating that OsTET3may be also localed on the same membrane compared. All this findings laid a solid foundation in futher function analysis and role of Xa7disease resistance to anlysis the resitant signaling pathway of Xa7.