Nadarajah Kalaivani, Omar Nurfarahana Syuhada, Rosli Marhamah Md, Shin Tze Ong
School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
Biomed Res Int. 2014;2014:434257. doi: 10.1155/2014/434257. Epub 2014 Aug 28.
Two field isolates of Rhizoctonia solani were isolated from infected paddy plants in Malaysia. These isolates were verified via ITS-rDNA analysis that yielded ~720 bp products of the ITS1-5.8S-ITS4 region, respectively. The sequenced products showed insertion and substitution incidences which may result in strain diversity and possible variation in disease severity. These strains showed some regional and host-specific relatedness via Maximum Likelihood and further phylogenetic analysis via Maximum Parsimony showed that these strains were closely related to R. solani AG1-1A (with 99-100% identity). Subsequent to strain verification and analysis, these isolates were used in the screening of twenty rice varieties for tolerance or resistance to sheath blight via mycelial plug method where both isolates (1801 and 1802) showed resistance or moderate resistance to Teqing, TETEP, and Jasmine 85. Isolate 1802 was more virulent based on the disease severity index values. This study also showed that the mycelial plug techniques were efficient in providing uniform inoculum and humidity for screening. In addition this study shows that the disease severity index is a better mode of scoring for resistance compared to lesion length. These findings will provide a solid basis for our future breeding and screening activities at the institution.
从马来西亚受感染的水稻植株中分离出两株立枯丝核菌田间分离株。通过ITS-rDNA分析对这些分离株进行了验证，该分析分别产生了ITS1-5.8S-ITS4区域约720 bp的产物。测序产物显示出插入和替换发生率，这可能导致菌株多样性以及疾病严重程度可能存在差异。通过最大似然法分析，这些菌株显示出一些区域和宿主特异性相关性，通过最大简约法进行的进一步系统发育分析表明，这些菌株与立枯丝核菌AG1-1A密切相关（同一性为99-100%）。在菌株验证和分析之后，通过菌丝块法利用这些分离株对20个水稻品种进行纹枯病耐受性或抗性筛选，两个分离株（1801和1802）对特青、TETEP和茉莉85均表现出抗性或中度抗性。根据病情严重程度指数值，分离株1802的毒性更强。该研究还表明，菌丝块技术在提供均匀接种物和湿度以进行筛选方面是有效的。此外，该研究表明，与病斑长度相比，病情严重程度指数是一种更好的抗性评分方式。这些发现将为我们机构未来的育种和筛选活动提供坚实的基础。
