title: Molecular characterization and screening for sheath blight resistance using Malaysian isolates of Rhizoctonia solani.
abstract: 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.
authors.affiliation: School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
authors.forename: Kalaivani
authors.identifier: 0000-0002-9854-3219
authors.initials: K
authors.lastname: Nadarajah
authors.affiliation: School of Environmental and Natural Resources Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
authors.forename: Nurfarahana Syuhada
authors.identifier: 0000-0001-6244-895X
authors.initials: NS
authors.lastname: Omar
authors.affiliation: School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
authors.forename: Marhamah Md
authors.initials: MM
authors.lastname: Rosli
authors.affiliation: School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi Selangor, Malaysia.
authors.forename: Ong
authors.initials: O
authors.lastname: Shin Tze
mesh_terms: D001483:Base Sequence; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics* / Q000276:immunology; D016013:Likelihood Functions; D008296:Malaysia; D008969:Molecular Sequence Data; D012275:Oryza / Q000276:immunology* / Q000382:microbiology*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D012232:Rhizoctonia / Q000235:genetics* / Q000302:isolation & purification* / Q000502:physiology; D017422:Sequence Analysis, DNA
chemical_list: D021903:DNA, Ribosomal Spacer