Thiabendazole resistance and mutations in the 13-tubulin gene ofPenicillium expansum strains isolated from apples and pears withblue mold decay

摘要

Penicillium expansum is the causal agent of blue mold rot, a postharvest decay ofstored fruits. This fungus also produces the mycotoxins patulin and citrinin.Control of P. expansum still relies mainly on the use of fungicides such asthiabendazole. Since its introduction, resistant strains have been reported. Theaim of this work was to investigate the thiabendazole resistance and mutations inthe β-tubulin gene of P. expansum strains isolated from apples and pears with bluemold decay from Spain. A total of 71 strains of P. expansum were scored forresistance to thiabendazole and the 13-tubulin gene was sequenced. Out of 71strains, 37 were sensitive and 34 were resistant to thiabendazole. Regarding theβ-tubulin gene sequence, 10 different genetic types were determined, with a99.7-100% similarity. When the amino acid sequence was deduced, five differentamino acid sequences were found. All except one of the sensitive strains lackedmutations in the region sequenced. Of the 34 resistant strains, only eight hadmutations that involved the residues 198 and 240. All the strains with mutations atposition 198 always corresponded to resistant isolates. However, a high percentageof resistant strains had no mutations in the region of the β-tubulin genesequenced, and so other mechanisms may be involved in thiabendazole resistance.