Detection and quantification of Rhizoctonia solani AG-1 IA, the rice sheath blight pathogen, in rice using real-time PCR

Rhizoctonia solani Kühn is the causal organism of sheath blight, a major rice disease worldwide that severely impairs yield and quality. It is difficult to identify the pathogen in the early phase of the infection and to accurately quantify the fungal development based on visual inspection. Therefore, a rapid and reliable method is advantageous for the detection and quantification of the pathogen causing this important rice disease. In this study, a real-time, quantitative polymerase chain reaction (QPCR) assay was developed to detect and quantify R. solani AG-1 IA DNA from infected rice plants. A specific primer pair was designed based on the internal transcribed spacer region of the fungal ribosomal DNA. The specific detection of R. solani DNA was successful with quantities as low as 1 pg. The QPCR assay could be used for detecting the rice sheath blight pathogen, quantifying fungal aggressiveness, and evaluating the resistance level of rice cultivars.