Vegetative-compatibility groups in Verticillium dahliae from Israel.
Nitrate-nonutilizing (nit) mutants were used to determine vegetative compatibility among 34 isolates of V. dahliae from cotton, potatoes, olives, aubergines, chrysanthemums and tomatoes from 12 sites in Israel. Based on the formation of complementary heterokaryons, 33 isolates were assigned to 2 vegetative compatibility groups (VCGs). One VCG contained 15 isolates from cotton, aubergines, chrysanthemums and olives, and the other contained 18 isolates from potatoes, olives and cotton. One isolate from tomatoes was compatible with both VCGs. In a limited pathogenicity test with 10 isolates, 2 (from tomato and aubergines) were pathogenic on tomatoes, aubergines and cotton. Most isolates from cotton were only pathogenic on cotton and aubergines, and one isolate from cotton was non-pathogenic. Fewer isolates were pathogenic on tomatoes than on cotton or aubergines. It is concluded that the diversity of vegetative compatibility found in this V. dahliae collection was comparable to that found in studies of American populations.