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Disease Note.

Systemic Infection of Cowpea by Two Isolates of Brome Mosaic Virus. R. A. Valverde, Department of Plant Pathology, University of California, Davis 95616. Plant Dis. 71:557. Accepted for publication 11 March 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0557C.

The reaction of 20 cowpea (Vigna unguiculata (L.) Walp. subsp. unguiculata) lines to three brome mosaic virus (BMV) isolates (BMV-I, BMV-2, and BMV-type [ATCC PV47]) (1) was evaluated after mechanical inoculation. Only one cowpea line, Tvu 612, developed necrotic local lesions and systemic mosaic after inoculation with BMVI or B MV -2. This same line reacted with only a few necrotic lesions and no systemic infection afterinoculation with BMV -type. The two isolates infecting cowpea systemically were back-inoculated to barley, then reisolated. These two isolates were confirmed by host reaction, serology, and electrophoretic analysis of their double-stranded RN As before and after passage through cowpea. The isolates showed no differences in serological properties or in mobilities of double-stranded RNAs. Symptoms induced by BMV-I and BMV-2 on barley did not change after passage through cowpea. This is the first report of BMV causing systemic infection in a legume.

Reference: (1) R. A. Valverde. Plant Dis. 67:1194,1983.