The diversity of Sclerotinia sclerotiorum (Lib.) de Bary isolates from western Poland

Sclerotinia sclerotiorum (Lib.) de Bary is one of the most dangerous pathogens of rapeseed (Brassica napus L.). Rape plants are infested most often in spring during the flowering phase. The aggressive nature of this fungus as well as its pathogenicity is attributed to its mycotoxin, particularly oxalic acid. Oxalic acid is responsible for the development of acid environment in the plant which triggers off activity of hydrolytic enzymes. The developing crystals of calcium oxalate contribute to destabilisation of pectin compounds found in the cell wall. Moreover, oxalic acid also acts as a suppressor of reactive oxygen forms (H₂O₂). In this study isolates of the S. sclerotiorum were collected in the years 2012–2014 from three different locations. Collective of isolates described as populations. Two hundred twenty eight (228) isolates of S. sclerotiorum were characterized by evaluation of the total amount of acids produced by the pathogen and at molecular level using Random Amplified Polymorphic DNA (RAPD). Statistical differences were found in acids production by particular S. sclerotiorum isolates collected in the years 2012–2014. Moreover, a relationship was found between acids production and the rate of linear mycelium growth. High similarity between pathogen isolates from the same locality was found using RAPD analysis with twelve primers and small genetic differences between pathogen isolates depending on the place of origin.