Characterization and Proteomic Analysis of Novel Rice Lesion Mimic Mutant with Enhanced Disease Resistance

Lesion mmic mutants(LMMs)are plants that spontaneously form lesions without pathogeninfection or external stimulus and exhibit resistance to pathogens.Here,a rice LMM was created by ethylmethane sulfonate mutagenesis,named as hpil(hydrogen peroxide induced lesion).Diaminobenzidineand trypan blue staining showed that large amounts of H_(2)O_(2) were produced and cell death was occurredat and around the parts of lesion mimic in the rice leaves.The phenotype of hpil is controlled by a singlerecessive gene,localized at a 2 Mb interval on chromosome 2.The data suggested that hpil is a novelLMM with enhanced bacterial and fungal disease resistance,and multiple pathogenesis-related proteins(PRs)were up-regulated.The proteomes of leaves at three positions(different degrees of lesion mimicseverity)were characterized in hpil compared with its wild type plant.Differentially expressed proteinswere detected by two dimensional difference gel electrophoresis and 274 proteins were identified byMALDITOF/TOFTM.These proteins were related to metabolic process,cellular process and response tostimulus,with mostly down-regulated in hpil leaves.Many of these proteins were related to the Calvincycle,photosynthetic electron transport chain,glycolysis/gluconeogenesis and phosphonates pathways.Some resistance-related proteins including 14-3-3 proteins,OsPR10 and antioxidases such asperoxidase,superoxide dismutase and ascorbate peroxidase were up-regulated in leaves with lesionmimic.These results provide the foundation for cloning of the target gene and shed light on themechanism involved in autaimmunity of rice.