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Genetics

Vegetative Compatibility Groups in Fusarium oxysporum f. sp. lycopersici. Karol S. Elias, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803-1720; R. W. Schneider, Department of Plant Pathology and Crop Physiology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803-1720. Phytopathology 81:159-162. Accepted for publication 12 September 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-159.

A worldwide collection of 115 isolates of Fusarium oxysporum f. sp. lycopersici from tomato was examined for pathogenicity, colony morphology, and vegetative compatibility. No correlations were found between colony morphology and length of time in culture, race, vegetative compatibility group (VCG), or geographic origin. Vegetative compatibility group 0030 contained all three races of F. o. lycopersici and all colony morphology types. Vegetative compatibility groups 0031 and 0032 contained races 1 and 2, but their geographic ranges were somewhat more limited. In addition, 50 isolates of F. o. lycopersici were the sole members of a VCG (VCG 003-). Thus, no correlation existed between VCG and race. The occurrence of all three races from diverse locations (Australia, Florida, and California) in the same VCG indicates that several genetic determinants responsible for race specificity may exist within genetically isolated clonal populations (VCGs). While VCG has no known association with pathogenicity, it provides a new trait with which to further characterize fungal strains. More importantly, these previously undefined entities suggest the existence of genetic limits that could govern paths of gene flow related to the origin of races in F. o. lycopersici.