Influence of RNA composition of beet necrotic yellow vein furovirus isolates and of the sugarbeet cultivar on the translocation of the virus in mechanically inoculated sugarbeet roots1

Abstract

The roots of young sugarbeet seedlings (5‐12 days old) were inoculated mechanically with beet necrotic yellow vein furovirus (BNYVV). Vortexing of the seedlings in virus‐containing suspensions proved to be especially effective. Higher percentages of infected tap roots were observed with a highly susceptible than with a tolerant cultivar. In the susceptible cultivar, the virus spread more readily from the tap root to the newly formed lateral roots than in the tolerant cultivar, indicating that the latter had a partial resistance to the virus. The translocation of the virus also depended on its RNA composition. An isolate with intact RNA3 and RNA4 was much more efficiently translocated to the lateral roots than an isolate which lacked these two RNAs. So far we have been unable to infect hairy roots of sugarbeet with BNYVV. These hairy roots had been induced by infection with Agrobacterium rhizogenes and were propagated in liquid culture.