Identification of two acetylcholinesterases in Pardosa pseudoannulata and the sensitivity to insecticides.
Pardosa pseudoannulata is an important predatory enemy against insect pests, such as rice planthoppers and leafhoppers. In order to understand the insecticide selectivity between P. pseudoannulata and insect pests, two acetylcholinesterase genes, Pp-ace1 and Pp-ace2, were cloned from this natural enemy. The putative proteins encoded by Pp-ace1 and Pp-ace2 showed high similarities to insect AChE1 (63% to Liposcelis entomophila AChE1) and AChE2 (36% to Culex quinquefasciatus AChE2) with specific functional motifs, which indicated that two genes might encode AChE1 and AChE2 proteins respectively. The recombinant proteins by expressing Pp-ace1 and Pp-ace2 genes in insect sf9 cells showed high AChE activities. The kinetic parameters, Vmax and Km, of two recombinant AChE proteins were significantly different. The sensitivities to six insecticides were determined in two recombinant AChEs. Pp-AChE1 was more sensitive to all tested insecticides than Pp-AChE2, such as fenobucarb (54 times in Ki ratios), isoprocarb (31 times), carbaryl (13 times) and omethoate (6 times). These results indicated that Pp-AChE1 might be the major synaptic enzyme in the spider. By sequence comparison of P. pseudoannulata and insect AChEs, the key amino acid differences at or close to the functional sites were found. The locations of some key amino acid differences were consistent with the point mutation sites in insect AChEs that were associated with insecticide resistance, such as Phe331 in Pp-AChE2 corresponding to Ser331Phe mutation in Myzus persicae and Aphis gossypii AChE2, which might play important roles in insecticide selectivity between P. pseudoannulata and insect pests. Of course, the direct evidences are needed through further studies.
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China.
Yixi
Y
Zhang
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Ying
Y
Shao
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Feng
F
Jiang
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Jian
J
Li
Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: jemunson@njau.edu.cn.
Zewen
Z
Liu
D000110:Acetylcholinesterase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D060829:Arthropod Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D007306:Insecticides / Q000633:toxicity*; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013112:Spiders / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics
D060829:Arthropod Proteins; D007306:Insecticides; D000110:Acetylcholinesterase
Acetylcholinesterase; Insecticide selectivity; Pardosa pseudoannulata