An antenna-biased carboxylesterase is specifically active to plant volatiles in Spodoptera exigua.
Odorant-degrading enzymes (ODEs) in sensillar lymph are proposed to play important roles in the maintenance of the sensitivity of the olfactory sensilla, by timely degrading the odorants that have already fulfilled the activation of the odorant receptor (OR). Here we reported the cloning and characterization of an ODE gene (SexiCXE10) from the polyphagous insect pest Spodoptera exigua. SexiCXE10 is a carboxylesterase (CXE) gene, encoding a protein with 538 amino acid residues, and bearing typical characteristics of Carboxyl/cholinesterase (CCE, EC 3.1.1.1.) gene family. Tissue-temporal expression pattern by qPCR revealed that the SexiCXE10 mRNA was highly antenna biased, and maintained at high level throughout the adult stage. Further fluorescence in situ hybridization demonstrated that SexiCXE10 mRNA signal was detected under sensilla basiconica and short and long sensilla trichodea. Finally, enzymatic study using purified recombinant enzyme showed that SexiCXE10 had high activity specifically for ester plant volatiles with 7-10 carbon atoms, while no activity was found with S. exigua sex pheromone components and plant volatiles with more carbon atoms. In addition, SexiCXE10 displayed lower activity at acidic pH (pH 5.0), while higher activity was found at neutral and alkaline conditions (pH 6.5-9.0). Our results suggest that SexiCXE10 may play an important role in the degradation of the host plant volatiles, and thus contributes to the high sensitivity of the olfactory system in S. exigua. Meanwhile, the CXE would be a potential target for developing behavioral antagonists and pesticides against S. exigua.
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Guizhou University, Ministry of Education, Guiyang 550025, China.
Peng
P
He
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China; College of Life Sciences, Huaibei Normal University, Huaibei 235000, China.
Ya-Nan
YN
Zhang
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Ke
K
Yang
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Zhao-Qun
ZQ
Li
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: sldong@njau.edu.cn.
Shuang-Lin
SL
Dong
D000818:Animals; D057506:Arthropod Antennae / Q000201:enzymology; D043182:Carboxylesterase / Q000235:genetics* / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D018411:Spodoptera / Q000201:enzymology*
D019476:Insect Proteins; D043182:Carboxylesterase
Spodoptera exigua; antennae-enriched expression, general odorant-degrading enzyme; carboxylesterase; kinetic parameters