title: Silencing an N-acyltransferase-like involved in lignin biosynthesis in Nicotiana attenuata dramatically alters herbivory-induced phenolamide metabolism.
abstract: In a transcriptomic screen of Manduca sexta-induced N-acyltransferases in leaves of Nicotiana attenuata, we identified an N-acyltransferase gene sharing a high similarity with the tobacco lignin-biosynthetic hydroxycinnamoyl-CoA:shikimate/quinate hydroxycinnamoyl transferase (HCT) gene whose expression is controlled by MYB8, a transcription factor that regulates the production of phenylpropanoid polyamine conjugates (phenolamides, PAs). To evaluate the involvement of this HCT-like gene in lignin production as well as the resulting crosstalk with PA metabolism during insect herbivory, we transiently silenced (by VIGs) the expression of this gene and performed non-targeted (UHPLC-ESI/TOF-MS) metabolomics analyses. In agreement with a conserved function of N. attenuata HCT-like in lignin biogenesis, HCT-silenced plants developed weak, soft stems with greatly reduced lignin contents. Metabolic profiling demonstrated large shifts (up to 12% deregulation in total extracted ions in insect-attacked leaves) due to a large diversion of activated coumaric acid units into the production of developmentally and herbivory-induced coumaroyl-containing PAs (N',N''-dicoumaroylspermidine, N',N''-coumaroylputrescine, etc) and to minor increases in the most abundant free phenolics (chlorogenic and cryptochlorogenic acids), all without altering the production of well characterized herbivory-responsive caffeoyl- and feruloyl-based putrescine and spermidine PAs. These data are consistent with a strong metabolic tension, exacerbated during herbivory, over the allocation of coumaroyl-CoA units among lignin and unusual coumaroyl-containing PAs, and rule out a role for HCT-LIKE in tuning the herbivory-induced accumulation of other PAs. Additionally, these results are consistent with a role for lignification as an induced anti-herbivore defense.
authors.affiliation: Department of Molecular Ecology, Max Planck Institute for Chemical Ecology, Jena, Germany. egaquerel@ice.mpg.de
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gaquerel
authors.forename: Hemlata
authors.initials: H
authors.lastname: Kotkar
authors.forename: Nawaporn
authors.initials: N
authors.lastname: Onkokesung
authors.forename: Ivan
authors.initials: I
authors.lastname: Galis
authors.forename: Ian T
authors.initials: IT
authors.lastname: Baldwin
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000577:Amides / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D003373:Coumaric Acids / Q000737:chemistry / Q000378:metabolism; D020868:Gene Silencing; D060434:Herbivory / Q000502:physiology*; D008031:Lignin / Q000096:biosynthesis*; D018402:Manduca / Q000502:physiology; D013058:Mass Spectrometry; D008954:Models, Biological; D009538:Nicotine / Q000378:metabolism; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018547:Plant Stems / Q000033:anatomy & histology / Q000648:ultrastructure; D011700:Putrescine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D011801:Quinic Acid / Q000378:metabolism; D012995:Solubility; D013095:Spermidine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000469:parasitology*
chemical_list: D000577:Amides; D003373:Coumaric Acids; D010636:Phenols; D010940:Plant Proteins; D011801:Quinic Acid; D009538:Nicotine; D008031:Lignin; D000217:Acyltransferases; D013095:Spermidine; D011700:Putrescine