Hidden diversity of yellow dwarf viruses in Australian cereals

Yellow dwarf viruses (YDVs) are widespread and economically important pathogens of cereals globally. YDVs belong to the genus Luteovirus (family Tombusviridae) or the genus Polerovirus (family Solemoviridae). Despite their importance, information about the genetic diversity of YDVs is scarce, especially in an Australian context. Seventeen symptomatic cereal and grass plants from Australia were analysed using high-throughput sequencing (HTS). Twenty-five YDV genomes were revealed by HTS and were identified as barley yellow dwarf virus PAV (5/25), barley yellow dwarf virus PAS (3/25), cereal yellow dwarf virus RPV (6/25), barley virus G (3/25), cereal yellow dwarf virus RPS (1/25), and a novel luteovirus (7/25) that had likely been serologically misidentified previously as barley yellow dwarf virus MAV. The first full genome sequence of an Australian CYDV RPS isolate is also described. Despite the fact that this was only a snapshot of the virus profile in one region of Australia at one point in time, Australian YDVs were found to be surprisingly diverse. This information is critical for the development of virus-resistant cereal varieties and more-effective diagnostic tests and demonstrates the complex nature of YDV epidemiology and taxonomy.