Studies On Resistance Of Fusarium Spp. From Wheat To Carbendazim And Polymorphism Of Fusarium Graminearum In Sichuan

Fusarium Head Blight(FHB) is an important disease on triticeae crops production around the world. It is also one of the three serious disease of wheat in Sichuan China. It has been for several decades of using carbendazim(MBC) to control the wheat scab(Fusarium spp.) and other fungal diseases. Studies showed that many fungi which include Fusarium graminearum had already produced serious drug resistance to benzimidazole fungicide. The first stain F.graminearum which is drug-resistance to MBC was found in Zhejiang in 1992. Today, F. graminearum has had a serious resistance to MBC. In order to determine the resistance level of F.graminearum to MBC and the genetic diversity of F.graminearum in Sichuan Province, the Fusarium spp. of wheat scab were identified, studied on resistance to MBC and analysised by RAPD which were collected from 14 areas in Sichuan Province between 2008 and 2010.The results revealed that 185 strains of Sichuan Province were grouped into six Fusarium species, which were 176 F.graminearum,4 F. avenaceum,2 F. tricinctum, 1 F. moniliforme,1 F. culmorum and 1 F.nivale. The isolation frequency of them were 95.14%,2.16%,1.08%,0.54%,0.54% and 0.54%,respectively. Using three different resistant wheat varieties to determinate the differentiation of pathogenicity, the results shows that:all the isolates had pathogenicity, and there are significantly different of the pathogenicity of Fusarium spp.The resistance to MBC of the 185 strains Fusarium spp. which were collected from Sichuan between 2008 and 2010 were determined. Our results shown that, there was no found the strain which EC50 was up to more than triple. The EC50 of all the strains were between 0.3853～1.5243μg/mL, they have difference 3.956 times, and the average of EC50 was 0.6238μg/mL. The strains which EC50 are more than the baseline were 62.05% of all tested strains. The MIC of all strains were between 0.8910～5.3910μg/mL. The strain collected from Suining is of the highest value of MIC, also it is of the maximum value of EC50. The average EC50 and MIC of Fusarium spp. of Sichuan are respectively 0.6255μg/mL and 1.7381μ/mL. The result reveals that the extremum resistant level to MBC of Fusarium spp. of Sichuan is higher than contrast.Six random primers were used for RAPD analysis for eighty-seven Fusarium graminearum. A total of 69 patterns were multiplied, and the patterns are between 300 and 1000bp. The frequency of polymorphic were accounted for 79.71%.The research illustrated that the F. graminearum had rich genetic diversity in Sichuan. The genetic distance is between 0.0581 and 0.6380. All strains obviously forming there groups after clustering analysis. GroupⅡcontains 82 isolates, the percentage was 94.3%. GroupⅠandⅢrespectively had 3 and 2 strains. Clustering analysis showed that most F. graminearum from a single area could not cluster together. It is provided that the F. graminearum did not have distinct geographic division.