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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. |