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Physiology and Biochemistry

Partial Characterization and Grouping of Isolates of Blackeye Cowpea Mosaic and Cowpea Aphidborne Mosaic Viruses. M. A. Taiwo, Former graduate student, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; D. Gonsalves(2), R. Provvidenti(3), and H. D. Thurston(4). (2)(3)Associate professor, and senior research associate, respectively, Department of Plant Pathology, New York State Agricultural Experiment Station, Cornell University, Geneva 14456; (4)Professor, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Phytopathology 72:590-596. Accepted for publication 18 August 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-590.

The biological, physical, and some biochemical properties of single isolates of blackeye cowpea mosaic virus (BICMV) from Florida and New York were compared with those of single isolates of cowpea aphidborne mosaic virus (CAMV) from Cyprus, Morocco, Kenya, and Nigeria. On the basis of reactions on selected cowpea lines, the six isolates were classified into the BICMV or CAMV group. No common source of resistance was found for both CAMV and BICMV, but cowpea lines with resistance to each virus group were identified. These resistant lines were used for differentiating the isolates as BICMV or CAMV. The BICMV group consisted of the Florida and New York isolates of BICMV and the Kenya and Nigeria isolates of CAMV, whereas the CAMV group included the Morocco and Cyprus isolates. In reciprocal cross-protection tests, neither the Kenya nor Florida isolates cross-protected against the Morocco isolate, and vice versa. However, the size of the capsid protein, the sedimentation rate of the nucleic acid, and the length of the particles of the six isolates were very similar. The impact of this regrouping on the taxonomic status of BICMV and CAMV is discussed.