Optimized Yellow Dwarf Virus Multiplex PCR Assay Reveals a Common Occurrence of <i>Barley yellow dwarf virus</i>-PAS in Kansas Winter Wheat

Barley yellow dwarf is an aphid-transmitted virus disease caused by yellow dwarf virus (YDV) species in the family Luteoviridae. Previous partial sequencing efforts conducted in Kansas revealed that Barley yellow dwarf virus-PAS (PAS) occurs in winter wheat fields, and currently available YDV multiplex reverse-transcription PCR (RT-PCR) assays do not detect this species. To enable precise determination of YDV species for research, disease diagnostic, and plant breeding programs, this study enhanced and validated the utility of a multiplex RT-PCR protocol to discriminate six YDV species, including PAS, in archived and fresh field samples. From a representative subset of samples collected from commercial and variety trial locations across nine wheat growing regions of Kansas, PAS and Barley yellow dwarf virus-PAV (PAV) were equally prevalent in single or mixed infections, and other YDVs occurred in mixed infections with PAS and/or PAV in low numbers. The optimized multiplex assay provided robust and specific detection of YDVs and showed promise as a diagnostic tool for determining species occurrence and composition of YDVs in an intensive wheat cropping region of the United States.