Novel molecular Mechanisms Associated with Different Phenotype of Benzimidazole Fungicide Resistance in the Wheat Scab Gibberella zeae
会议名称：《中国植物病理学会2005年学术年会暨植物病理学报创刊50周年纪念会》
会议日期：2005年
学科分类：09[农学] 0904[农学-植物保护] 090401[农学-植物病理学] 090402[农学-农业昆虫与害虫防治]
摘 要：Three sensitivity phenotypes of wild-type sensitivity, high and moderate resistance were identified among field strains of Gibberella zeae to the benzimidazole fungicide carbendazim (MBC). The whole sequence of the beta-tubulin gene from twenty-eight G. zeae strains representing the three field phenotypes and from five G. zeae laboratory MBC-resistance mutants was separated using PCR. No alternative change was found at the beta-tubulin gene in all MBC-resistant strains both from field and laboratory. Thus, it can be concluded that the mechanism of G. zeae to MBC-resistance is different from other filamentous fungi, which was caused by point mutation at amino acid position 198 or other position of beta-tubulin gene. To look for the carbendazim resistance mechanism of G. zeae, microtubule-associated protein gene (map) and other members of tubulin gene family, i.e. alpha-, alpha2-, gamma-, and no-named tubulins were also cloned and analyzed. The results revealed that there was not any mutation found in alpha-, alpha2-, gamma-tubulins genes and map among three sensitivity phenotypes. However, alternation at codon 33, 64 and 66 in a no-named tubulin gene, which had 997 bp lengths, including one intron, encoding 313 amino acids, corresponded to the different phenotype sensitivities, respectively. At Codon 33, TTT encoding phenylalanine in MBC-sensitive isolates was converted to TAT coding tyrosine in field middle MBC-resistance strains. At codon 64, GAG was altered into CTG resulting in substitution of glutamic acid for leucine in a field high benzimidazole-resistance isolate. While one-nucleotide mutation GAG into AAG also at the same codon 64 resulted in the single amino acid substitution of glutamic acid for lysine in UV induced high MBC-resistance mutants. But at codon 66, only a different single point mutation of TTC (in sensitive isolates) to TAC (in the NT07 isolate) caused a change of phenylalanine (Phe) to a tyrosine (Tyr) expressing middle resistance level, too.