Resistant mechanism of Fusarium graminearum against carben-dazim,unrelative to alpha2-tubulin gene

Abstract:

[Objective] We studied the resistance of Fusarium graminearum against carbendazim, to confirm if the resistance was related to the whole nucleotide sequence of alpha2-tubulin. [Methods] The whole nucleotide sequence of alpha2-tubulin and morphological characteristic were analyzed from different sensitivie strains when treated with carbendazim. [Results] The results indicated that both sensitive strains and moderately resistant strains produced tube with swelled abnormality or germlings with more branches or cells of conidium swelled greatly, when treated with carbendazim at their EC50 or EC90. The full-length nucleotide sequence of α2-tubulin gene from each of 8 F. graminearum strains from China, which had different carbendazim (MBC) sensitivity phenotypes, were separated by using PCR with 4 primer sets designed in accordance with nucleotide sequence of the gene from the genomic sequencing strain, NRRL 31084 (PH-1). The DNA sequence comparison showed no difference in the nucleotide sequence of α2-tubulin gene among 4 sensitive and 4 resistant strains. This result demonstrates that there was no relationship between MBC-resistance and alpha2-tubulin gene. The full-length of the gene spanned 1712 bp, including 4 introns, encoding 453 amino acids. With 100% homology, there were 5 nucleotide differences in alpha2-tubulin gene between PH-1 isolate and the 6 strains from China. The homology of the deduced amino acid sequence of the gene was 100% among the 6 strains and PH-1 isolate, and 64%-89% among other 9 species of fungi. [Conclusion] The resistance of F. graminearum against carbendazim was irrelative to the nucleotide sequence of alpha2-tubulin.

Key words:Fusarium graminearum; alpha2-tubulin gene; morphology characteristics; carbendazim-resistance