Abstract:

Rice bacterial leaf streak(BLS) caused by the pathogen Xanthomonas oryzae pv. oryzicola (Xooc) is one of the major rice diseases in South China. Here we focus on proteomics as a tool for the discovery of differentially expressed proteins closely related to the disease resistance. The leaves of rice cultivar Jiafuzhan (Oryzae sativa L.) highly resistant to the disease, were infected by “89773-1-1” strain of the Xooc with strong pathogenicity. Total proteins were extracted from the leaves sampled at two days after inoculation, and separated by two-dimensional electrophoresis. It was found that there were thirty-eight proteins expressed differentially, of which thirty-two were up-regulated, five down-regulated and one was “new”. Of the thirty-eight responsive proteins, thirty-three were identified by MALDI-TOF-MS and database searching. Based on the predicted function, we grouped them into four clusters: signal transduction, defensive responses, substance metabolism and protein stabilization, which were involved in many resistant physiological reactions, including signal recognition and transduction, antioxidant reaction, carbonhydrate metabolism, cell-wall reinforcement and phytoalexin biosythesis. In turn a complex signal transduction and metabolic regulative network in the resistant responses to the infection of Xooc was outlined in this work, and the molecular mechanism was revealed by differentially expressed protein /enzyme patterns during Xooc infection. In this study, eight R proteins and three pathogenesis-related(PR) proteins which might relate closely to the disease-resistance were found. This result provides us the basic information to further reveal the resistant mechanism and conduct functional cloning of the resistant-related genes in rice to BLS.

Key words: Rice (Oryza sativa L.), Bacterial leaf streak of rice (BLS), Proteomics