Analysis of mycelial compatibility and pathogenicity of Sclerotinia sclerotiorum isolated from oilseed crops in Canada, China,USA and England

摘要

Objectives of this study were to understand the genetic and pathogenic variations of Sclerotinia sclerotiorum isolates originating from a worldwide collectior. For this purpose, 160 isolates recovered from oiiseed crops in China (71 isolates), Canada (39 isolates), the United States (20 isolates) and England (30 isolates) were evaluated for their mycelial compatibility and pathogenicity by comparing their differences on radial growth, aggressiveness, sclerotial yield and productions of oxalic acid and total acids. Mycelial compatibility group (MCG) testing identified 44 MCGs, of which, 56.8% were represented by single strains.Isolates fiom different countries were incompatible except those in MCG11 and MCG17, which were collected from Manitoba (MB), Canada and its neighboring North Dakota (ND), USA. There were significant differences in terms of radial growth,sclerotial yield, aggressiveness, production of oxalic acid and total acids within tested isolates and among MCGs (P＜0.0001)regardless of their geographic origins. Correlation analysis indicated that mycelial growth was positively related to aggressiveness (r=0.46), oxalic acid production (r=0.2) and total acids secretion (r=0.31), but not to the yield of sclerotia produced on PDA (r=0.09). Aggressiveness was positively related to oxalic acid concentration (r=0.74) and negatively related to the production of total acids (r=-0.75). Additionally, there was high positive relationship between pH and oxalic acid production (r=0.9).