Identification of Rice Blast Resistance Mutant lmm326 and Preliminary Analysis of Its Regulatory Pathway
[Objective]Rice lesion mimic mutants often have a certain resistance to rice blast. To understand the genetic mechanisms behind its blast resistance, we identified the rice lesion mimic mutant lmm326 and analyzed its regulatory pathway. [Method] lmm326 was obtained from an EMS-induced Zhonghua 11 mutant bank, and population derived from lmm326/ Zhonghua 11 and lmm326/Dular were used for genetic and fine mapping. [Result]At 5-leaf stage, there were brown lesions on lower leaves of lmm326 initially. Compared with the wild type(WT), photosynthetic pigment contents, net photosynthetic rate, plant height, seed setting rate, tiller number, and 1000-grain weight of lmm326 were significantly reduced. Evans blue and DAB staining assay indicated that leaves of lmm326 accumulated more dead cells and H2O2. Additionally, lmm326 displayed higher resistance to 4 races of rice blast compared with WT. According to genetic analysis, the phenotype of mutant was controlled by a single recessive gene. Here, we employed map-based cloning approach to finely map LMM326 through F2 population derived from a cross between lmm326 and Dular, and the gene was narrowed to a 38-kb region on the long arm of chr. 1, which harbored six ORFs. Sequence analysis revealed that a single base substitution at position C433T in Os01g0919900 CDS resulted in a substitution of leucine for phenylalanine at position 145. Real-time PCR showed that expression levels of defense-related genes were significantly higher in lmm326 than in WT.[Conclusion]These results demonstrated that the target gene is allelic to OsSSI2, and LMM326 is likely to participate in salicylic acid-signaling pathway, and its mutation activates the defense response.
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万方数据
维普
