Characteristic Expression Of WRKY Transcriptional Factors In Rice Development And Interaction With Xanthomonas Oryzae Pv.oryzae

Background: Rice (Oryza sativa) is a very important crop, and one of important model of Monocotyledon plants. With the completion of the Rice Genome Project, the next step forward is to define the biological function of target proteins. Bacterial blight, causes by Xanthomonas oryzae pv. Oryzae (Xoo), is one of the most serious diseases of rice, which can reduce the yield of rice, it can even result in the lost of harvest. Xa21 is the first disease resistance gene cloned from rice, which confers broad spectrum resistance against Xoo. WRKY transcription factors, one of the largest gene families in rice genome, are reported to play important roles during disease resistance, biotic and abiotic stress signaling pathways.Aim: The generation of specific antibodies against rice WRKY proteins to investigate the expression profiling of rice WRKY proteins in different stages of rice leaves. Then we screened WRKY proteins which associated with the Xa21-mediated resistance against bacterial leaf blight to accumulate basic information for functional studies.Material and method: Epitopes were predicted for candidate gene-encoded proteins and polypeptides were synthetized. Polyclonal antibodies were generated by rabbit immunization. Western blotting (WB) analysis was carried out for rice material collected at different developmental stages, further we examined their expression at different time points in the Xa21-mediated resistance against bacterial leaf blight. Comparison analysis with transcription information derived from rice MPSS database.Results: In this experiment, five of WRKY-specific antibodies were selected for detect protein expression in rice leaves at different developmental stages, and the expression patterns of WRKY were revealed. We found that OsWRKY13, OsWRKY23 and OsWRKY71 were expressed and increased steadily with growth of leaves, which decreased at maturity stage. Moreover the expression of OsWRKY45, OsWRKY53, OsWRKY71 were up-regulated in the later period of the resistance reaction. Comparing their expression in the resistance, susceptible and mock responses, we found that changes in resistance and susceptible responses were more obvious than those in Mock response. Furthermore, most of the changes in the susceptible response were more obvious than those in the disease resistance response. To statistic analyze about MPSS tags of leaves development and different injected Xoo times, we compared analysis association with transcription and protein level information.Conclusion: By the expression profiling of 5 WRKY proteins in different stages of rice leaves, we found that the proteins have curve of growth in leaves and relation with Xoo. OsWRKY13, OsWRKY23 and OsWRKKY71 may work in normal leaf development. OsWRKY45, OsWRKY53, OsWRKY71 proteins played a role in both of the resistance and susceptible responses, which are related with the degrees of their expression. There are close relations between protein existence, expression variance and disease-resistant. Our study revealed that the expression of WRKY proteins is relevant to rice development and the resistance and susceptible responses in the interaction between rice and Xoo. It provided important scientific basis for chloroplast function in vital processes such as rice normal growth and response of adversity.