Submitted to: Proceeding Of 66th Congress International Institute for Beet Research
Publication Type: Proceedings
Publication Acceptance Date: 2/26/2003
Publication Date: 8/20/2003
Citation: LEWELLEN, R.T., LIU, H., WINTERMANTEL, W.M., SEARS, J.L. INHERITANCE OF BEET NECROTIC YELLOW VEIN VIRUS (BNYVV) SYSTEMIC INFECTION IN CROSSES BETWEEN SUGARBEET AND BETA MACROCARPA. PROCEEDING OF 66TH CONGRESS INTERNATIONAL INSTITUTE FOR BEET RESEARCH. 2003. p. 149-160. Interpretive Summary: Beet necrotic yellow vein virus (BNYVV), the cause of rhizomania in sugarbeet, rarely goes systemic from natural soil-borne infection or from mechanical inoculation in sugarbeet. However, in the wild relative of sugarbeet, Beta macrocarpa that grows as a weedy annual in the Imperial Valley of California, it almost always goes systemic from mechanical inoculation. It was of scientific interest to determine the genetic basis of this significant difference between these Beta species. From hybridization between sugarbeet and B. macrocarpa, F2, F3, F4, BC1, F1, BC1, F2, and BC1, F3 populations were evaluated for systemic infection following mechanical inoculation. There was strong evidence that systemic infection (susceptibility) was inherited as a single recessive factor and that non-systemic infection (resistance) was conditioned by dominance. These results add knowledge to the inheritance of reaction types to this very important disease of sugarbeet.
Technical Abstract: Beet necrotic yellow vein virus (BNYVV), the cause of rhizomania, rarely infects sugarbeet (Beta vulgaris L.) systemically. Conversely, from mechanical inoculation BNYVV almost always systemically infects B. vulgaris subsp. macrocarpa (B. mac) line that grows as a weedy annual in the Imperial Valley of California. This B. mac has been used for many years in the virology programs at Salinas as an indicator host for virus assays. B. mac shows other reactions to viruses that are of interest. When infected young, Beet yellows, Beet mosaic, and Beet curly top viruses kill B. mac. Other "nonbeet" viruses, e.g., Lettuce mosaic virus, readily produce systemic infection in B. mac but not in sugarbeet. It was of interest to determine the genetic basis of these different host-plant reactions. B. mac is a very easy bolting annual and highly self-fertile and successful crosses were achieved only when sugarbeet was used as the female. Color patterns and annualism were used as markers to positively identify F1 hybrids. The very limited number of F1 plants tested had the virus reaction of sugarbeet or were intermediate. The F2 suggested that BNYVV systemic infection was conditioned by a homozygous recessive factor but the lack of fit may have been caused by escapes and lethal and sublethal mutant plants and to incomplete expressivity. F3 population and F3 line patterns also suggested recessive inheritance, but again ratios appeared disturbed. Most F3 plants produced from F2 plants with systemic infection to BNYVV were susceptible to systemic infection and there was no evidence for seed transmission. Evaluation of segregating populations is continuing with the intent to produce a biennial line with the virus reactions of B. mac and to determine if different genes for host reaction are involved for each virus or if one recessive factor is predisposing B. mac to be widely susceptible to systemic infection by numerous viruses.