DIFFERENTIATION OF COTTON ISOLATES OF VERTICILLIUM DAHLIAE FROM CHINA ON THE BASIS OF PATHOGENICITY, VEGETATIVE COMPATIBILITY ANDRAPD ANALYSIS

摘要

Based on pathogenicity test, 16 of the 50 isolates of Verticillium dahliae collected from 10 cotton-growing provinces in China were identified as defoliating strains and 35 as non-defoliating strains. With 5 isolates failing to produce any nit mutantsand 1 isolate being vegetatively self-incompatible, 16 defoliating isolates were classified into one group (VCG 1) where the American defoliating strains T9 and V-44 occurred, and 29 non-defoliating isolates into VCG 2. 44 Chinese isolates with T9, V-44and 115 as reference were analyzed by means of RAPD. Isolates tested were differentiated into 7 clusters designated RAPD Groups I-VII, respectively. RAPD Groups I, II, III and V each included only one isolate, while RAPD Groups IV, VI and VII contained43 of the 47 isolates tested. All the 28 isolates clustered into RAPD Groups I, II, III, IV and VI were non-defoliating strains and belonged to VCG 2. With one exception of the defoliating isolate HU0209 differentiated as a single RAPD Group, all the rest 15 Chinese defoliating isolates were clustered into RAPD VII, where the American defoliating strains T9 and V-44 occurred. RAPD Group VII also included a non-defoliating isolate (HB1610) which was assigned into VCG 2.This study first reports the occurrence of defoliating strains in Hubei and Beijing and suggests that RAPD analysis could be used as a powerful tool in population analysis of V. dahliae for the purpose of ecological and epidemical studies of Verticillium wilt of cotton.