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
Department of Molecular Biology, College of Natural Science, Sejong University, Seoul 143-747, South Korea.
Plant Physiol Biochem. 2005 Apr;43(4):397-406. doi: 10.1016/j.plaphy.2005.03.002. Epub 2005 Apr 7.
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 degrees 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.
在此，我们对一个水稻（Oryza sativa L.）稻瘟病类病斑（blm）突变体进行了特征分析，该突变体先前在品种华城（野生型）经N-甲基-N-亚硝基脲诱变的群体中被鉴定出来。该水稻blm在长日照条件下发育过程中以及在无明显胁迫/病害情况下温度从28摄氏度转变为24摄氏度时，叶片上会自发形成坏死病斑，为我们在生长室中研究blm提供了一个高度可重复且便捷的实验系统。blm表型类似于过敏反应（HR）中的细胞死亡，随后，二维凝胶电泳（2-DGE）显示许多叶片蛋白被诱导；其中突出的是5类（一个斑点）和10类（两个斑点）的三种病程相关（PR）标记蛋白。有趣的是，水稻blm对所有测试的稻瘟病菌（Magnaporthe grisea）小种都表现出HR，以非小种特异性方式提供高抗性。还观察到blm对过氧化氢处理具有高度抗性。通过2-DGE免疫印迹，我们仅在blm中鉴定出4个与超氧化物歧化酶（SOD）抗体发生交叉反应的新斑点，表明在病斑形成过程中可能有新的SOD蛋白（同工型）表达。在blm的叶片中，自发荧光化合物在病斑扩展部位及其周围积累。此外，在blm的叶片中还观察到两种主要水稻植保素樱花素和稻壳醇A的水平升高。这些结果表明blm赋予对多种病原体的广谱抗性，因此，可以推测BLM基因产物可能控制类似HR的细胞死亡及其相关的多种防御信号通路，如水稻中与防御反应相关的已知标志性特征（蛋白质/代谢物）的诱导所证明的那样。
