Author
|
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Proceedings Publication Acceptance Date: 2/18/2014 Publication Date: 12/19/2014 Citation: Jia, Y. 2014. Development of a pathology toolbox for genetic and breeding for resistance to rice sheath blight disease. Proc. 35th Rice Tech. Work. Group Meet., New Orleans, LA, p.86. Feb 18-21, 2014. CDROM. Interpretive Summary: Technical Abstract: Accurate evaluation of the host response of rice plants to sheath blight disease, Rhizoctonia solani, is important for genetic studies and breeding for improved resistance. In the present study, a method to evaluate the response of a recombinant inbred mapping population, consisting of 574 F10 individuals derived from a cross of susceptible cultivar Lemont with a moderately resistant cultivar Jasmine 85, and an easy to use method for mass production of R. solani for field study were developed. For evaluation of the mapping population individuals to R. solani, rice seeds were sown into a 96-cell tray (1 seedling/cell) and grown to the 3-4 leaf stage for pathogen inoculation. R. solani was grown on PDA media. A single agar plug containing mycelia was attached to each individual sheath immediately above the soil. Inoculated plants were placed in plastic containers and covered with a lid to maintain humidity; and kept in a greenhouse at 24-30°C. Disease lesions were measured using a ruler approximately 3-5 days after inoculation. The average of the disease lesions from three replicate plants was used as the disease rating for each line of the mapping population. This method reduces time and greenhouse space needed for phenotyping as compared to previously developed methods. For mass production of R. solani inoculant for field evaluations, fungal mycelia from PDA plates were used to inoculate a sterile mixture of corn and rye in a plastic container and covered with a lid. The inoculated mixture was maintained under regular white florescent light at room temperature (21-25°C) for approximately two weeks until the appearance of white sclerotia. The fungal mixture was then air dried at room temperature with a fan for one week and then pulverized. Detached leaf inoculations were performed to verify pathogenicity of R. solani. Leaf tissue from Lemont, on moist filter paper in covered Petri dishes, were inoculated with agar plugs with mycelia, from recently produced inoculant, and kept at room temperature. Disease lesions were observed three days after inoculation and pathogenicity of R. solani was verified. This method is fast, inexpensive, and can be easily implemented in any laboratory. In summary, a simple and easy to use method for evaluation of host response and mass production of R. solani were developed. It was anticipated that these methods will accelerate genetic studies and breeding efforts for improved sheath blight resistance. |
