A Novel Gene Enhances UV-B Tolerance and Disease Resistance in Rice

Plants, because of their immobility, are forced to adapt to various stresses like heat, ultraviolet radiation and pathogen infection. The common feature of the adaptive responses, developed by plants to survive, is the activation and repression of certain genes upon perception of an external stimulus. Transcription factors, proteins that cause activation or inactivation of genes by direct binding to the DNA, play major roles in adaptive responses. A family of transcription factors, the WRKY proteins, is known to be involved in defense against pathogen attacks and have been characterized in Arabidopsis, tobacco and parsley.

 A member of the WRKY transcription factors family, OsWRKY89, has recently been demonstrated to enhance ultraviolet-B tolerance and pathogen resistance in rice. Transgenic rice lines overexpressing the OsWRKY89 gene are shown to be resistant to the rice blast fungus and the white-backed planthopper, major pests in rice production around the world. The expression of the gene also stimulated several pathways related to UV-B radiation protection including wax deposition in leaves, synthesis of secondary metabolites and lignin and changes of the redox status. Possible application of the findings in developing rice lines with increased rice blast resistance and UV-B tolerance is currently being studied.

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