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Resistance

Temperature-Influenced Virus Movement in Expression of Resistance to Soilborne Wheat Mosaic Virus in Hard Red Winter Wheat (Triticum aestivum). L. Drumm Myers, senior agriculturist, Department of Plant Pathology, Oklahoma State University, Stillwater 74078; J. L. Sherwood(2), W. C. Siegerist(3), and R. M. Hunger(4). (2)(4)professors, Department of Plant Pathology, Oklahoma State University, Stillwater 74078; (3)senior agriculturist, Department of Plant Pathology, Oklahoma State University, Stillwater 74078. Phytopathology 83:548-551. Accepted for publication 30 January 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-548.

Soilborne wheat mosaic (SBWM) disease, caused by the soilborne wheat mosaic furovirus (SBWMV), is a major disease of hard red winter wheat (Triticum aestivum) in the plains states. The virus is transmitted by the soilborne fungus (Polymyxa graminis. Although cultivars expressing resistance to SBWM have been developed, information regarding the mechanism(s) of resistance is lacking. When resistant (Hawk and Newton) and susceptible (Sage and Vona) cultivars were planted in soil containing viruliferous P. graminis under conditions conducive for fungal and subsequent viral infection, SBWMV was readily detected by ELISA in roots of all cultivars but was detected in the foliage of only the susceptible cultivars. When the cultivars were mechanically inoculated with SBWMV the virus was detected in the foliage and later in the roots of all cultivars, indicating downward translocation of virus was not impeded in any of the cultivars. The reaction of resistant and susceptible cultivars to SBWMV was similar when the cultivars were initially grown at 15 C, so infection by viruliferous P. graminis occurred, and then transferred to 23 C. Virus was detected in the roots and foliage of all cultivars. Thus, resistance to SBWMV may be related to differential virus movement in resistant versus susceptible cultivars with temperature modulating the expression of the resistance.