Functional Identification Of SDKB Gene In Rice Through RNA Interference

The Arabidopsis thaliana NPR1 is a positive regulator in systemic acquired resistance (SAR). To identify the function of SDKB, an Arabidopsis thaliana NPR1 homologous gene in rice, an RNAi rice expression vector pCAMBIA 1301-ihp for silencing SDKB was constructed. Rice cultivar Gui99 was transformed with pCAMBIA 1301-ihp by Agrobacterium tumefaciens-mediated transformation. Six hygromycin resistant regenerated seedlings were obtained. They were confirmed to be transgenic plants through PCR and Southern hybridization analysis. The result of RT-qPCR revealed that the SDKB expression level in the T1 progeny of three transgenic plants was 16.15%, 3.49% and 15.07% of that in wild-type plant respectively, showing a significant suppresssion of SDKB expression. The Tl plants of the three transgenic lines developed a lesion length which was 1.7, 1.9 and 2.3 folds to wild-type plant respectively after challenged with Xanthomonas oryzae pv.oryzae and had a disease index which was 1.4, 1.7 and 1.6 folds to wild-type plant respectively after inoculated with Magnaporthe grise, showing an increased susceptibility to both Xoo and M.grise. These results confirmed that SDKB played a positive role in rice disease resistance regulation and had a potential application value in disease resistance improvement for rice and other crops.