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Physiology and Biochemistry

Effect of Heat Treatment upon Cowpea Chlorotic Mottle Virus Ribonucleic Acid Replication. W. O. Dawson, Department of Plant Pathology and Cell Interaction Group, University of California, Riverside, CA 92521; J. L. White(2), and G. L. Grantham(3). (2)(3)Department of Plant Pathology and Cell Interaction Group, University of California, Riverside, CA 92521. Phytopathology 68:1042-1048. Accepted for publication 24 January 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1042.

The synthesis of cowpea chlorotic mottle virus (CCMV) RNA was suppressed in cowpea leaves maintained at supraoptimal temperatures. Viral RNA synthesis was reduced about 80% in leaves maintained continuously at 35 C, and there was no evidence of viral RNA synthesis in leaves incubated continuously at 40 C. When leaves in which the virus was replicating rapidly at 25 C were shifted to 40 C, the synthesis of single-stranded CCMV RNA was immediately inhibited followed by a more gradual decline in capacity for synthesis of all species of viral RNA, even when returned to 25 C. The concentration of CCMV replicase declined in leaves incubated at 40 C in a manner suggesting that the decline in virus synthesis capacity resulted from prolonged incubation at 40 C was due to loss of replicase activity. When leaves that had been incubated at 40 C were returned to 25 C and maintained at that temperature, synthesis of CCMV RNA resumed after 4 to 12 hr. Single-stranded CCMV RNA produced at 25 C was stable when incubated at 40 C.