Quantitative detection of the rice false smut pathogen Ustilaginoidea virens by real-time PCR.

Rice false smut (RFS) is an important rice disease that is caused by the pathogen Ustilaginoidea virens. In this study, we developed a real-time polymerase chain reaction (PCR) assay to detect U. virens and to estimate the level of disease. The genomic DNAs of U. virens and rice were extracted together from the rice samples. Real-time PCR assays were performed and compared to conventional nested-PCR assays. The real-time PCR assay presented a consistent linearity of the standard curve (R(2) = 0.9999). The detection limit could be as low as 40 fg U. virens DNA with a rice genomic DNA background on using the real-time PCR assay, which showed significantly higher sensitivity than the conventional nested-PCR assay. We conclude that the real-time PCR quantitative assay is a useful tool for detecting U. virens and for early defense and control of RFS.