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Physiology and Biochemistry

A New Strain of Southern Bean Mosaic Virus Derived at Low Temperatures. M. H. McGovern, Department of Plant Pathology, University of Georgia, Athens 30602; C. W. Kuhn, Department of Plant Pathology, University of Georgia, Athens 30602. Phytopathology 74:95-99. Accepted for publication 24 June 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-95.

A new strain of southern bean mosaic virus (SBMV), designated NCP, was derived when certain cowpea lines were inoculated with the cowpea strain (CP) and maintained at 21 and 24 C. NCP was serologically different from CP and three other strains of SBMV. Strain CP caused necrotic local lesions on cowpea cultivar Clay and plant introduction (PI) 399419, while NCP caused no symptoms on Clay and local chlorosis and systemic mosaic on PI 399419. The two strains also differed in susceptibility of their RNAs to proteinase K and virion accumulation in cultivar Clay. NCP partially overcame the resistance in cultivar Clay, but had no appreciable effect on the resistance of three other cultivars. Four interacting factors were responsible for the derivation of NCP: host, temperature, viral replication, and viral movement. We speculate that the new strain induces some substance that aids or is required for systemic movement of the virus within the host.