|Rush, Charles - TEXAS A&M, AG EXPER STA|
|Steddom, Karl - TEXAS A&M, AG EXPER STA|
|Jones, David - TEXAS A&M, AG EXPER STA|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 25, 2005
Publication Date: July 30, 2005
Citation: Rush, C.M., Steddom, K., Jones, D.C., Campbell, L.G. 2005. Association of the Rz gene with plants expressing symptoms of rhizomania in disease tolerant cultivars [abstract.]Phytopathology. 95:S91. Technical Abstract: In 1996, <i>Beet necrotic yellow vein virus</i>(BNYVV), the cause of rhizomania, was identified in sugar beet fields in Southern Minnesota. Fortunately, cultivars with strong genetic tolerance to the disease, conferred by a single dominant gene name <i>Rz1</i>, were available and are now widely planted. In 2003 individual plants exhibiting typical symptoms of rhizomania were identified in fields planted to rhizomania tolerant cultivars. These symptomatic plants, termed "blinkers", and apparently healthy plants were collected, rated for disease severity, tested for the presence of the virus and the <i>Rz</i> gene, percent sucrose was determined, and leaf chlorosis was quantified with an integrating sphere. When data was sorted between blinkers and healthy plants, blinkers had significantly higher disease ratings, higher reflectance at 555nm, higher virus titer, and lower sugar content. When only blinkers were included in the analysis, 42% tested positive for presence of the <i>Rz</i> gene but there was no difference in disease severity ratings between blinkers with and without the <i>Rz</i>gene. This suggests that disease tolerence conferred by the <i>Rz</i> gene has been overcome by BNYVV, but the specific cause for the genetic breakdown is unknown.