Chaipanya Chaivarakun, Telebanco-Yanoria Mary Jeanie, Quime Berlaine, Longya Apinya, Korinsak Siripar, Korinsak Siriporn, Toojinda Theerayut, Vanavichit Apichart, Jantasuriyarat Chatchawan, Zhou Bo
Department of Genetics, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
Genetics and Biotechnology Division, International Rice Research Institute, Los Baños, Laguna, 4031, Philippines.
Rice (N Y). 2017 Dec;10(1):18. doi: 10.1186/s12284-017-0159-0. Epub 2017 May 11.
Rice (Oryza sativa) is one of the most important food crops in the world. Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most destructive rice diseases worldwide. To effectively cope with this problem, the use of rice blast resistance varieties through innovative breeding programs is the best strategy to date. The Thai rice variety Jao Hom Nin (JHN) showed broad-spectrum resistance against Thai rice blast isolates. Two QTLs for blast resistance in JHN were reported on chromosome 1 (QTL1) and 11 (QTL11).
Monogenic lines of QTL1 (QTL1-C) and QTL11 (QTL11-C) in the CO39 genetic background were generated. Cluster analysis based on the disease reaction pattern of QTL1-C and QTL11-C, together with IRBLs, showed that those two monogenic lines were clustered with IRBLsh-S (Pish) and IRBL7-M (Pi7), respectively. Moreover, sequence analysis revealed that Pish and Pi7 were embedded within the QTL1 and QTL11 delimited genomic intervals, respectively. This study thus concluded that QTL1 and QTL11 could encode alleles of Pish and Pi7, designated as Pish-J and Pi7-J, respectively. To validate this hypothesis, the genomic regions of Pish-J and Pi7-J were cloned and sequenced. Protein sequence comparison revealed that Pish-J and Pi7-J were identical to Pish and Pi7, respectively. The holistic disease spectrum of JHN was found to be exactly attributed to the additive ones of both QTL1-C and QTL11-C.
JHN showed broad spectrum resistance against Thai and Philippine rice blast isolates. As this study demonstrated, the combination of two resistance genes, Pish-J and Pi7-J, in JHN, with each controlling broad-spectrum resistance to rice blast disease, explains the high level of resistance. Thus, the combination of Pish and Pi7 can provide a practical scheme for breeding durable resistance in rice against rice blast disease.
水稻（Oryza sativa）是世界上最重要的粮食作物之一。由真菌病原体稻瘟病菌（Magnaporthe oryzae）引起的稻瘟病是全球最具破坏性的水稻病害之一。为有效应对这一问题，通过创新育种计划培育抗稻瘟病品种是目前最好的策略。泰国水稻品种Jao Hom Nin（JHN）对泰国稻瘟病菌株表现出广谱抗性。已报道JHN中位于第1号染色体（QTL1）和第11号染色体（QTL11）上的两个抗稻瘟病QTL。
在CO39遗传背景下构建了QTL1（QTL1-C）和QTL11（QTL11-C）的单基因系。基于QTL1-C和QTL11-C以及IRBLs的病害反应模式进行聚类分析，结果表明这两个单基因系分别与IRBLsh-S（Pish）和IRBL7-M（Pi7）聚类。此外，序列分析表明Pish和Pi7分别位于QTL1和QTL11界定的基因组区间内。因此，本研究得出结论，QTL1和QTL11可分别编码Pish和Pi7的等位基因，分别命名为Pish-J和Pi7-J。为验证这一假设，对Pish-J和Pi7-J的基因组区域进行了克隆和测序。蛋白质序列比较表明，Pish-J和Pi7-J分别与Pish和Pi7相同。发现JHN的整体病害谱完全归因于QTL1-C和QTL11-C两者的累加效应。
JHN对泰国和菲律宾的稻瘟病菌株表现出广谱抗性。如本研究所示，JHN中两个抗性基因Pish-J和Pi7-J的组合，每个基因都控制对稻瘟病的广谱抗性，解释了其高水平的抗性。因此，Pish和Pi7的组合可为培育水稻对稻瘟病的持久抗性提供一个实用方案。
