Rhizomania resistance in the Tandem® sugar beet variety

Rhizomania, caused by beet necrotic yellow vein virus (BNYVV), is a major disease of sugar beet world-wide. The 'Holly' resistance gene (Rz1) confers strong resistance to several BNYVV isolates and has been incorporated into most major sugar beet breeding lines. However, the threat presented by resistance-breaking isolates of BNYVV, to which the Holly gene does not confer adequate resistance, underscores the need for novel sources of Rhizomania-resistant germplasm. The Tandem (R) sugar beet variety combines resistances to BNYVV from two sources: the Rz1 gene and a proprietary Beta maritima-derived source. Beets from Tandem, Holly-mediated resistant, and susceptible non-Rz lines were harvested from replicated microplots with heavy Rhizomania disease pressure in the Red River Valley (Minnesota and North Dakota, U.S.), and were analyzed for virus accumulation, root yield, sugar content and juice purity parameters. BNYVV titers were significantly and uniformly lower in samples from Tandem (R) or Holly than those from the susceptible controls.