棉蚜抗氧化乐果品系的羧酸酯酶基因突变

用氧化乐果对室内敏感品系棉蚜Aphis gossypii (Glover)进行抗性选育，经24代筛选，抗性指数达到124.7倍。以α-乙酸萘酯（α-NA）为底物，比较了氧化乐果敏感和抗性品系棉蚜羧酸酯酶的比活力，发现抗性品系羧酸酯酶比活力明显小于敏感品系。对这两个品系的羧酸酯酶基因进行了克隆，通过对抗性和敏感品系羧酸酯酶基因核苷酸序列及推导的氨基酸序列比较，发现抗性品系有4个氨基酸残基发生了替代 (His¹⁰⁴→Arg, Ala¹²⁸→Val, Thr³³³→Asp, Lys⁴⁸⁴→Arg)。对其蛋白质三维结构分析推测只有His¹⁰⁴→Arg的替代是位于其活性中心。棉蚜氧化乐果敏感和抗性品系羧酸酯酶基因cDNA全长的GenBank登录号分别为AY485216和AY485214。

The mutation of carboxylesterase gene of cotton aphid, Aphis gossypii associated with omethoate resistance

 A laboratory susceptible strain （YSS） of cotton aphid, Aphis gossypii (Glover), was selected with omethoate in successive generations in the laboratory to develop a resistant strain (YRR ). After 24 generations, the resistance ratio of YRR strain was increased by 124.7-fold compared with the omethoate-susceptible strain. Carboxylesterase activity was significantly lower in the omethoate-resistant strain than in the omethoate-susceptible strain when α-naphthyl acetate （α-NA）was used as substrate. A  carboxylesterase gene had been fully cloned and equenced from both omethoate-susceptible and resistant strains. Comparison of both nucleic acid and deduced amino acid sequences revealed  four nucleotide acid differences between the omethoate-susceptible and resistant strain, which resulted in four amino acid substitutions (His¹⁰⁴→Arg, Ala¹²⁸→Val, Thr³³³→Asp, Lys⁴⁸⁴→Arg). Knowledge of the structure of a related enzyme acetylcholinesterase) suggests that one of these substitutions (His¹⁰⁴→Arg) lies within the active site of the enzyme. The GenBank accession numbers of carboxylesterase genes of omethoate-resistant (YRRAA) and susceptible (YSSAA) A. gossypii are AY485216 and AY485214，respectively.