Intraspecific Diversity of Monilinia fructicola and M. laxa Populations from Blossoms and Fruit of Different Hosts in Greece.

The genetic variation among 145 isolates of Monilinia fructicola and 156 isolates of M. laxa collected from two distinct regions of Greece (Imathia and Larissa) was analyzed using intersimple-sequence repeat markers. The Monilinia spp. isolates had been collected from infected fruit or blossoms of peach, apricot, sweet cherry, and plum. Calculation of Nei's gene diversity and Shannon's diversity indices showed that M. fructicola populations had higher genetic diversity compared with M. laxa populations in both regions sampled. The levels of genetic diversity were similar between populations obtained from diseased blossoms and fruit for each species and the main variances were all from within rather than between populations for the respective regions, hosts, and organ of origin. Genetic distance (Nei's analysis) was lower between peach and apricot populations than between cherry and plum populations of M. fructicola. M. fructicola isolates from peach and apricot and from sweet cherry and plum were clustered together, while M. laxa isolates clustering based on the host of origin was not possible. The analysis of index of association showed the absence of sexual recombination for both species. The derived data support the hypothesis of a long presence of M. fructicola in Greece, and provide evidence of specialization of M. fructicola populations based on their host of origin.