The rice ( Oryza sativa) Blast Lesion Mimic Mutant, blm, may confer resistance to blast pathogens by triggering multiple defense-associated signaling pathways

• Published in: Plant physiology and biochemistry 2005-04, Vol.43 (4), p.397-406
• Main Authors: Jung, Young-Ho, Lee, Joo-Hee, Agrawal, Ganesh Kumar, Rakwal, Randeep, Kim, Jung-A, Shim, Jae-Kyung, Lee, Sang-Kyu, Jeon, Jong-Seong, Koh, Hee-Jong, Lee, Yong-Hwan, Iwahashi, Hitoshi, Jwa, Nam-Soo
• Format: Article
• Language: English
• Subjects: Antifungal Agents - metabolism; Biological and medical sciences; Blast pathogen; Cell physiology; Diterpenes - metabolism; Flavonoids - metabolism; Fundamental and applied biological sciences. Psychology; Hydrogen Peroxide - pharmacology; Lesion mimic mutant; Magnaporthe - pathogenicity; Magnaporthe grisea; Molecular and cellular biology; Mutation; Oryza - genetics; Oryza - metabolism; Oryza - microbiology; Oryza sativa; Oxidative Stress; Pathogenesis-related proteins and genes; Phenolics; Phenols - metabolism; Phytoalexins; Plant Diseases - genetics; Plant Diseases - microbiology; Plant Extracts - metabolism; Plant Proteins - genetics; Plant Proteins - isolation & purification; Plant Proteins - metabolism; Sesquiterpenes; Signal Transduction; Superoxide Dismutase - genetics; Superoxide Dismutase - isolation & purification; Superoxide Dismutase - metabolism; Terpenes
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2005.03.002

Here we characterized a rice ( Oryza sativa L.) blast lesion mimic ( blm) mutant, identified previously in an N-methyl- N-nitrosourea-mutagenized population of the cultivar Hwacheong (wild type). The rice blm displayed spontaneous necrotic lesion formation on the leaves during development under long-day condition and temperature shift from 28 to 24 °C in the absence of obvious stress/disease, and provided us with a highly reproducible and convenient experimental system in the growth chamber to study blm. The blm phenotype resembled to the cell death of hypersensitive reaction (HR), and subsequent, two-dimensional gel electrophoresis (2-DGE) revealed induction of many leaf proteins; prominent among them were the three pathogenesis-related (PR) marker proteins of class 5 (one spot) and 10 (two spots). Interestingly, the rice blm manifested HR against all races tested of the rice blast fungus ( Magnaporthe grisea), providing high resistance in a non-race specific manner. It was also observed that blm was highly resistant to hydrogen peroxide treatment. Using 2-DGE immunoblotting, we identified the presence of 4 new spots cross-reacting with a superoxide dismutase (SOD) antibody, only in blm, suggesting the expression of potentially new SOD protein (isoforms) during lesion formation. In the leaves of blm, autofluorescent compounds accumulated in and around the site of lesion progression. Moreover, enhanced levels of two major rice phytoalexins, sakuranetin and momilactone A were also observed in the leaves of blm. These results indicate that blm confers broad-spectrum resistance to multiple pathogens, and so, it could be hypothesized that the BLM gene product may control the HR-like cell death and its associated multiple defense signaling pathways, as evidenced by induction of known hallmark features (proteins/metabolites) linked with the defense responses, in rice.