Sugar beet yellow net complex contains a luteovirus component

Yellow net virus of sugar beet has, until now, been listed as a tentative member of the luteovirus genus, but this is the first study to show that the yellow net symptom (YN) is always associated with a luteovirus. This virus is related to beet mild yellowing virus (BMYV) and when transmitted alone causes a mild yellowing symptom similar to that caused by BMYV in beet. Plants with YN have been found to contain, in addition to the luteovirus, two prominent, low molecular weight double-stranded (ds)RNA species. This dsRNA is indicative of an extra component in a complex with the luteovirus, which gives rise to the conspicuous symptom. The range of experimental hosts for this virus has been extended to include Capsella bursa-pastoris and Physalis floridana.