Gossypol toxicity and detoxification in Helicoverpa armigera and Heliothis virescens.
Gossypol is a polyphenolic secondary metabolite produced by cotton plants, which is toxic to many organisms. Gossypol's aldehyde groups are especially reactive, forming Schiff bases with amino acids of proteins and cross-linking them, inhibiting enzyme activities and contributing to toxicity. Very little is known about gossypol's mode of action and its detoxification in cotton-feeding insects that can tolerate certain concentrations of this compound. Here, we tested the toxicity of gossypol and a gossypol derivative lacking free aldehyde groups (SB-gossypol) toward Helicoverpa armigera and Heliothis virescens, two important pests on cotton plants. Larval feeding studies with these two species on artificial diet supplemented with gossypol or SB-gossypol revealed no detectable toxicity of gossypol, when the aldehyde groups were absent. A cytochrome P450 enzyme, CYP6AE14, is upregulated in H. armigera feeding on gossypol, and has been claimed to directly detoxify gossypol. However, using in vitro assays with heterologously expressed CYP6AE14, no metabolites of gossypol were detected, and further studies suggest that gossypol is not a direct substrate of CYP6AE14. Furthermore, larvae feeding on many other plant toxins also upregulate CYP6AE14. Our data demonstrate that the aldehyde groups are critical for the toxicity of gossypol when ingested by H. armigera and H. virescens larvae, and suggest that CYP6AE14 is not directly involved in gossypol metabolism, but may play a role in the general stress response of H. armigera larvae toward plant toxins.
Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: ckrempl@ice.mpg.de.
Corinna
C
Krempl
Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: hfischer@ice.mpg.de.
Hanna M
HM
Heidel-Fischer
Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: gjimenez-aleman@ice.mpg.de.
Guillermo Hugo
GH
Jiménez-Alemán
Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: reichelt@ice.mpg.de.
Michael
M
Reichelt
Research Group Mass Spectrometry/Proteomics, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: rmenezes@ice.mpg.de.
Riya Christina
RC
Menezes
Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: boland@ice.mpg.de.
Wilhelm
W
Boland
Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: hvogel@ice.mpg.de.
Heiko
H
Vogel
Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: heckel@ice.mpg.de.
David G
DG
Heckel
Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745 Jena, Germany. Electronic address: nicole.joussen@gmx.de.
Nicole
N
Joußen
D000818:Animals; D000072472:Cytochrome P450 Family 6 / Q000235:genetics* / Q000378:metabolism; D006072:Gossypol / Q000378:metabolism*; D008658:Inactivation, Metabolic; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000254:growth & development / Q000378:metabolism*; D009036:Moths / Q000254:growth & development / Q000378:metabolism*
D019476:Insect Proteins; D000072472:Cytochrome P450 Family 6; D006072:Gossypol
CYP6AE14; Cytochrome P450; Gossypol detoxification; Helicoverpa armigera; Heliothis virescens; Insect plant interaction