| In this paper,91 samples including the stem and leaf of rice got bakanae disease were collected from Jiangyan, Jingjiang and Changzhou in Jiangsu province. After single spore isolation, and ITS sequences analysis.149 strains were isolated.77 strains were Fusarium fujikuroi,36 strains were F. graminearum,28 strains were F. equiseta and 8 strains were F. asiaticum.Among all isolated pathogens, there were 15 F. fujikuroi strains isolated from Jingjiang, accounting for 30.0% of the native populations.43 F. fujikuroi strains isolated from Changzhou, accounting for 76.8% of the native populations.19 F. fujikuroi strains isolated from Jiangyan accounting for 44.2% of the native populations. For the isolated Fusaria, F. fujikuroi had 51.68% proportion of the flora.By comparing the statistics of germination and excessive growth of rice seed treated by spores of different pathogens, the result showed that rice seed treated by spores of strain 81-1 had the lowest germination rate of 22.22%, rice seed treated by spores of strain 37-3 had the highest germination rate of 80.00%. Most of the rice plant seedling showed excessive growth, and excessive growth rate ranges from 4.10% to 61.14%. The maximum excessive growth plant was treated by strain 1-1. Only plant treated by strain 54-1 showed dwarf phenomenon, and plant excessive growth rate was -7.11%. Germination rate of more than 60% rice seeds was between 35% and 70% in Jingjiang and Jiangyan, however in Changzhou,56% rice seed was between 70% and 100%. Plant excessive rate is over 70% in Jingjiang, Jiangyan and Changzhou. These result showed that the isolates of Fusarium fujikuroi have different pathogenicities.Sensitivity of 77 F. fujikuroi strains to prochloraz was examined by mycelium growth rate method. EC50 of F. fujikuroi to prochloraz is 0.0196-1.3329 μg/mL, the maximum EC50 value is about 68 times of the minimum value. Strains had the lowest resistance in Jingjiang, average EC50 was 0.1589 μg/mL, and strains had the highest resistance in Changzhou, average EC50 was 0.2529 μg/mL. Average EC50 of strains in Jiangyan was 0.2021 μg/mL. To calculate the ratio of resistance, resistant strains accounted for 22.08% of the isolated strains,which showed F. fujikuroi had produced resistance to prochloraz in Jiangsu province.For cyp51 A sequences, compared with strain 30-2 (susceptible strain), thirty-eighth base of strain 54-3(resistant strain) changed from T to G, which equaled that the amino acid of 13th codon of resistant strain encods changed from glycine (Gly) to valine (Val). This change may be the reason for the high resistance.The sensitivity of 77 F. fujikuroi strains to JS399-19 was examined by mycelium growth rate method. The results showed that:EC50 of F. fujikuroi to JS399-19 is 0.0124-2.0400 μg/mL. Sensitivity frequency of 76 strains were unimodal distribution continuously, and the EC50 mean value was 0.6838)μg/mL±0.2649 μg/mL, which was considered as baseline-sensitivity of F. fujikuro to JS399-19 in Jiangsu. |
