Аннотация:Abstract Twenty‐four isolates of Verticillium dahliae from various geographic regions and host origins were assigned to vegetative compatibility groups (VCG) based on complementation between nitrate‐non‐utilizing ( nit ) mutants. The VCG assignment was associated with clearly distinguishable morphological and physiological characteristics. Most isolates of VCG 2B produced deep black colonies, small conidia (3.62 × 0.02 μ m), and spherical microsclerotia. They exhibited polyphenol oxidase (PPO) activity, high sporulation rate in shake cultures, fluorescence on sanguinarine‐amended PDA (snPDA) and excretion of dark pigment on Czapek Dox agar. The isolates assigned to VCG 4B had significantly longer conidia (4.73 × 0.04 μ m), spherical microsclerotia and white, fluffy colonies due to enhanced production of aerial mycelium. They excreted only traces of dark pigment, exhibited PPO activity, did not fluoresce on snPDA and had limited ability to sporulate in shake cultures. Except for lacking PPO activity the only heterokaryon self‐incompatible isolate (HSI) was similar to VCG 4B. Ten isolates of Verticillium longisporum from cruciferous hosts did not produce nit mutants. They had clearly longer conidia (7.41 × 0.05 μ m), formed elongate microsclerotia, and only poorly sporulated in shake cultures. They did not excrete dark pigment, lacked PPO, and failed to fluoresce on snPDA. The results indicate a clear morphological and physiological differentiation not only between the two species V. longisporum and V. dahliae but also among the VCGs of V. dahliae .
