Barley yellow dwarf virus and Cereal yellow dwarf virus Quantification by Real-Time Polymerase Chain Reaction in Resistant and Susceptible Plants

Reliable detection and quantification of barley and cereal yellow dwarf viruses (YDVs) is a critical component in managing yellow dwarf diseases in small grain cereal crops. The method currently used is enzyme-linked immunosorbent assay (ELISA), using antisera against the coat proteins that are specific for each of the various YDVs. Recently, quantitative real-time reverse-transcription polymerase chain reaction (Q-RT-PCR) has been used to detect bacterial and viral pathogens and to study gene expression. We applied this technique to detect and quantify YDVs using primers specific for Barley yellow dwarf virus-PAV (BYDV-PAV) and Cereal yellow dwarf virus-RPV (CYDV-RPV) coat protein genes because of the higher sensitivity of RT-PCR and the advantage of using a real-time PCR instrument. This Q-RT-PCR was used to detect BYDV and CYDV, and to examine disease development in a resistant wheatgrass, a resistant wheat line, a susceptible wheat line, and a susceptible oat line. BYDV-PAV and CYDV-RPV were detected as early as 2 and 6 h, respectively, in susceptible oat compared with detection by ELISA at 4 and 10 days postinoculation. BYDV-PAV RNA accumulated more rapidly and to a higher level than CYDV-RPV RNA in both oat and wheat, which may account for PAV being more prevalent and causing more severe viral disease than CYDV. Q-RT-PCR is reproducible, sensitive, and has the potential to be used for examining yellow dwarf disease and as a rapid diagnostic tool for YDVs.