Abstract:

Assessing the genetic diversity of Sclerotinia sclerotiorum isolates from different eco-geographical regions and host plants is crucially important for understanding the evolution of this fungal pathogen and its control. We detected DNA polymorphism of 76 S. sclerotiorum isolates from different regions and host plants using sequence-related amplified polymorphism (SRAP) markers. A total of 260 scorable fragments were identified with seven SRAP primer combinations; among them 114 were polymorphic loci (43.85%). UPMGA (Unweighted Pair Group Method with Arithmetic Mean) indicated that the dendrogram consisted of four groups, which included 54, 18, 2, and 2 isolates, respectively, when the genetic similarity coefficient was 0.64. Little genetic difference was identified among the isolates from different host species by cluster and principal component analyses. AMOVA (Analysis of Molecular Variance) revealed that the percentage of variation among populations differed by geographical region (24.8%, P<0.001) and by ecological region (18.8%, P<0.001), but variation among populations of different host plants was not different than expected at random (2.4%, P = 0.8673). One of our most significant results was that S. sclerotiorum isolates on rapeseed plants from winter and spring ecological regions can be divided into two clusters, and that genetic diversity in isolates of spring rapeseed ecological regions was higher than that of winter rapeseed ecological regions.