GENETIC DIVERSITY OF MICRODOCHIUM-NIVALE ISOLATES FROM TURFGRASS

Conserved primers were used in a polymerase drain reaction to amplify the ITS region of the rDNA of 100 Microdochium nivale isolates collect ed from different turfgrasses in southern Ontario. The profile of the restriction digestion of the amplified ITS region revealed that all th e M. nivale isolates analysed belonged to var. nivale. RAPD profiling and RFLP analyses of the IGS regions of rDNA revealed extensive geneti c diversity within var. nivale. With RAPD markers, the average similar ity coefficient was 66% and the estimate of genotypic diversity was 0. 179. Population subdivision analysis showed that 92.2% of the total ge netic diversity was found among individuals within populations compare d to 7.8% among populations. In dendrograms derived from genetic dista nces using RAPD and IGS-RFLP markers, there was some evidence for host specialization. Most RAPD markers were shared by individuals from dif ferent turfgrasses, and the populations were not highly differentiated . The high level of genotypic diversity detected within populations an d the low level of genetic differentiation among populations show that recombination and migration are likely playing important roles in the population biology of M. nivale var. nivale.