Disease Note.

Bean Calico Mosaic, a New Disease of Common Bean Caused by a Whitefly-Transmitted Geminivirus. J. K. Brown, Department of Plant Pathology, University of Arizona, Tucson 85721. M. A. Chapman, and M. R. Nelson. Department of Plant Pathology, University of Arizona, Tucson 85721. Plant Dis. 74:81. Accepted for publication 30 August 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0081D.

A geminivirus was isolated from common bean (Phaseolus vulgaris L.) plants collected in Obregon, Sonora, Mexico. Bright calico and mosaic symptoms and stunting were observed in about 60% of the plants in numerous fields. The virus was experimentally transmitted by Bemisia tabaci Genn. from field-infected bean to cv. Red Kidney bean, adzuki bean, cowpea, lima bean, Malva parviflora L., mungbean, soybean, and tepary bean but not to cotton, Datura stramonium L., lettuce, pepper, pumpkin, or tomato. In addition, the virus was transmitted by mechanical inoculation from field-infected bean to Red Kidney bean and Nicotiana benthamiana L. Transmission from virus source plants both by the whitefly vector and by mechanical means resulted in the development of typical calico and mosaic symptoms in bean test plants. Characteristic geminivirus particles (about 20 X 30 nm) were observed by TEM in extracts from symptomatic but not from healthy bean plants. Single-stranded DNA of approximately 2.6-2.7 kb was isolated from virus-containing preparations and visualized by gel electrophoresis. Sulfonated DNA probes prepared from the cloned 'A' component of bean golden mosaic virus (BGMV) as well as tomato golden mosaic virus (TGMV) showed only partial homology to the virus in dot-blot hybridization assays conducted under moderately stringent conditions (0.1 X SSC, 42 C). This is the first report of a whitefly-transmitted geminivirus causing a calico mosaic disease of bean in Sonora. The virus is tentatively designated herein as bean calico mosaic virus (BCMoV).