Development of a Specific Polymerase Chain Reaction System for the Detection of Rice Orange Leaf Phytoplasma Detection.

Rice orange leaf disease (ROLD), caused by rice orange leaf phytoplasma (ROLP), is transmitted by leafhopper vectors Recilia dorsalis and Nephotettix cinticeps. ROLD severely devastates rice production in Asia. Accurate detection of the pathogen is important for disease management. Current nested polymerase chain reaction (nested PCR) method using phytoplasma universal primers is widely used to detect phytoplasmas; however, it has shortcoming of inconvenience and inaccuracy, for it needs two round of PCR reactions and could produce false positive results due to nontarget amplification. In this study, we developed a PCR assay using a set of primers designed based on the ROLP genome sequence to amplify house-keeping gene FtsH-1 in rice and leafhopper vector samples. This method is simple and rapid, and its sensitivity up to 10 pg/μl of total ROLP DNA. It also minimizes the false positive problem produced by nested PCR. This method was used to survey the geographic distribution of ROLD in southern China from 2016 to 2018. The results showed that the distribution areas and vector carrying rate of ROLD had gradually increased.