Genetic diversity of Microdochium nivale isolates from turfgrass

Conserved primers were used in a polymerase chain reaction to amplify the ITS region of the rDNA of 100 Microdochium nivale isolates collected from different turfgrasses in southern Ontario. The profile of the restriction digestion of the amplified ITS region revealed that all the M. nivale isolates analysed belonged to var. nivale. RAPD profiling and RFLP analyses of the IGS regions of rDNA revealed extensive genetic diversity within var. nivale. With RAPD markers, the average similarity coefficient was 66% and the estimate of genotypic diversity was 0±179. Population subdivision analysis showed that 92±2% of the total genetic diversity was found among individuals within populations compared to 7±8% among populations. In dendrograms derived from genetic distances using RAPD and IGS-RFLP markers, there was some evidence for host specialization. Most RAPD markers were shared by individuals from different turfgrasses, and the populations were not highly differentiated. The high level of genotypic diversity detected within populations and 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.