|Effects of temperature on virus titer development and population growth of the wheat curl mite in wheat streak-resistant wheat cultivars.|
J. A. PRICE (1), A. Simmons (1), E. Evans (1), C. M. Rush (2). (1) Texas AgriLife Research, Amarillo, TX, U.S.A.; (2) Texas AgriLife Research, Bushland, TX, U.S.A.
The majority of winter wheat production in the Southern Great Plains serves as a dual purpose crop for both grazing and grain production, which exposes plants to warmer fall temperatures and a variety of pathogens, including <i>Wheat streak mosaic virus</i> (WSMV). Wheat varieties have been developed with resistance to WSMV; however the resistance is ineffective above 25C. Little is known about plant/virus interactions as temperatures fluctuate during the growing season, therefore, a study was conducted to determine the affects of temperature fluctuations on virus titer development and mite population dynamics in resistant winter wheat cultivars. Wheat cultivars Ron L and Mace, containing resistance, TAM 112, containing field tolerance, and TAM 111 and Karl 92, control plants, were grown in a growth chamber at 27C, infested with viruliferous wheat curl mites and moved to 18C and then to 5C. After three weeks exposure to each temperature, three tillers were collected from each plant for mite population counts and virus quantification, using real-time PCR. Preliminary results revealed that once infection occurred at high temperatures, Mace and Ron L were not able to recover, even at temperatures below the resistance threshold. However, TAM 112, which possesses no known specific resistance genes, supported a reduced number of mites and lower virus titer when compared with the other cultivars, thereby exhibiting an uncharacterized tolerance to both the virus and its vector.<p><p>Keywords: Virus-Viroid, Cereals-Grains, Wheat