Aphid transmissibility of onion yellow dwarf virus isolates with an N-terminal truncated HC-Pro is aided by leek yellow stripe virus

We recently reported that most of the onion yellow dwarf virus (OYDV) isolates detected from garlic in Hokkaido, Japan have a short HC-Pro. Because HC-Pro has been found to be necessary for aphid transmission, OYDV with a short HC-Pro (OYDV-S) conceivably may have lost aphid transmissibility. We here confirmed that OYDV-S was transmitted by aphids only when coinfecting the host with another potyvirus, leek yellow stripe virus (LYSV); OYDV with an intact HC-Pro was transmitted by aphids without LYSV. We presume that LYSV HC-Pro works in trans as a platform that interlinks both LYSV and OYDV-S with the aphid stylet.