Sequence Analysis Of The ITS Region For The Phytopathogenic Fungi Sclerotinia Species And Botrytis Cinerea

Isolates belonging to 4 species of Sclerotinia and Botrytis cinerea were identified based on pathogenicity analysis, determination of mycelial growth rate, observation of cultural characteristics on potato dextrose agar plates and analyses of their internal transcribed spacer sequence of the ribosomal gene. Results achieved so far are summarized below:1. Sclerotinia sclerotiorum grew faster than other 3 species belonging to this genus including S. trifloliorum, S. minor, and S. nivalis with radial growth rate of 18.5-19.8 mm/d for S. sclerotiorum, 13.5-14.0 mm/d for S. trifoliorum, 13.8-14.5 mm/d for S. minor and 11.9-12.4 mm/d for S. nivalis. The colonies of S. sclerotiorum, S. minor and S. nivalis formed on potato dextrose agar were thicher than those of S. trifoliorum. S. sclerotiorum, S. trifoliorum and S. nivalis produced larger, but fewer sclerotia than S. minor and the sclerotial yield for these 4 species were 11-22 per dish for S. sclerotiorum, 56-62 per dish for S. trifoliorum, 135-151 per dish for S. nivalis, but 522-551 per dish for S. minor. Both S. sclerotiorum and S. minor were strongly pathogenic to leaves of Chinese cabbage, S. trifoliorum was less pathogenic than the two species mentioned above and S. nivalis was weakly pathogenic.2. 5.8S-ITS regions of rDNA for 15 isolates belonging to Sclerotinia spp. and B. cinerea was amplified using the universal primer pair ITS 1 and ITS4, sequenced, aligned and analysis. The resultds showed that the ITS region has no variation or major variation for different strains within each species, regardless of their origin. Phylogenetic analysis of ITS aligned sequence reveals all strains of each species from different locations and different hosts formed a clade, which can be used to distinguish the other species.Sequences of the internal transcript spacer (ITS) region of Sclerotinia nivalis Saito isolated from three different hosts in Japan and Shengnongjia, Hubei, China, were determined. The comparison of ITS sequences among these strains and other strains of Sclerotinia spp. reported in GenBank was made. The results showed that no sequence of ITS identical to S. nivalis was found in GenBank. Therefore, the ITS sequences for the strain Let-19, AGT and C-1-2 were submitted to GenBank with the accessible number being DQ234388, DQ287338 and DQ287339. The ITS sequences of 11 tested strains of Sclerotinia spp. have been submitted to GenBank with accessible numbers.