Expression Profiling And Functional Characterization Of Rice Transcription Factor OsWRKY68

Rice(Oryza sativa L.)is one of the most important food crops in the world.WRKY protein is a large family of plant-specific transcription factors.There are nearly 100WRKY transcription factor family members in rice,and each WRKY transcription factor has its specific number and function.Previous study in our laboratory showed that,OsWRKY68 protein was induced after inoculation with Xanthomonas oryzae pv.oryzae(Xoo)in rice,and expressed constitutively in leaves at different developmental stages.As a number of abiotic stresses such as temperature,drought and salinity reduced the growth and yield of rice significantly,the functional investigation of WRKY transcription factors have important theoretical significance and application value for understanding rice normal growth and development,disease resistance and stress resistance mechanism.In this study,western blotting(WB)analysis were carried out using anti-OsWRKY68specific antibody,the expression patterns of OsWRKY68 protein under the rice normal growth and development,abiotic stress and hormone treatment were investigated systematically.OsWRKY68 protein was expressed constitutively in rice normal growth and development.The molecular weight of OsWRKY68 protein is about 32 kD,which is consistent with the prediction based on amino acid sequence.The abundance of OsWRKY68 protein was decreased along with time after salt stress and constant dark treatment.After constant light,MeJA and ET treatments,the OsWRKY68~+protein was appeared and increased with time.OsWRKY68 RNAi transgenic plants were identified by PCR and WB.The phenotypes of OsWRKY68 RNAi transgenic lines were identified,and the agronomic traits were analyzed.By identification four positive OsWRKY68 RNAi transgenic lines(Y316,Y317,Y326 and Y337)were obtained.The transgenic rice showed lower plant height,tiller number and seed setting rate.The salt tolerance test was carried out on transgenic rice,the root length,fresh weight and survival rate of OsWRKY68 RNAi transgenic lines were significantly higher than wild type.OsWRKY68 protein plays a crucial role during rice normal growth,knocking down OsWRKY68 protein abundance via RNAi technology affected rice normal growth and development.The abundance of OsWRKY68 protein was regulated by salt,darkness,light,MeJA and ET.Down-regulation the abundance of OsWRKY68 protein increased salt tolerance.