title: Role of aromatic aldehyde synthase in wounding/herbivory response and flower scent production in different Arabidopsis ecotypes.
abstract: Aromatic L-amino acid decarboxylases (AADCs) are key enzymes operating at the interface between primary and secondary metabolism. The Arabidopsis thaliana genome contains two genes, At2g20340 and At4g28680, encoding pyridoxal 5'-phosphate-dependent AADCs with high homology to the recently identified Petunia hybrida phenylacetaldehyde synthase involved in floral scent production. The At4g28680 gene product was recently biochemically characterized as an L-tyrosine decarboxylase (AtTYDC), whereas the function of the other gene product remains unknown. The biochemical and functional characterization of the At2g20340 gene product revealed that it is an aromatic aldehyde synthase (AtAAS), which catalyzes the conversion of phenylalanine and 3,4-dihydroxy-L-phenylalanine to phenylacetaldehyde and dopaldehyde, respectively. AtAAS knock-down and transgenic AtAAS RNA interference (RNAi) lines show significant reduction in phenylacetaldehyde levels and an increase in phenylalanine, indicating that AtAAS is responsible for phenylacetaldehyde formation in planta. In A. thaliana ecotype Columbia (Col-0), AtAAS expression was highest in leaves, and was induced by methyl jasmonate treatment and wounding. Pieris rapae larvae feeding on Col-0 leaves resulted in increased phenylacetaldehyde emission, suggesting that the emitted aldehyde has a defensive activity against attacking herbivores. In the ecotypes Sei-0 and Di-G, which emit phenylacetaldehyde as a predominant flower volatile, the highest expression of AtAAS was found in flowers and RNAi AtAAS silencing led to a reduction of phenylacetaldehyde formation in this organ. In contrast to ecotype Col-0, no phenylacetaldehyde accumulation was observed in Sei-0 upon wounding, suggesting that AtAAS and subsequently phenylacetaldehyde contribute to pollinator attraction in this ecotype.
authors.affiliation: Department of Horticulture and Landscape Architecture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Gutensohn
authors.forename: Antje
authors.initials: A
authors.lastname: Klempien
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Kaminaga
authors.forename: Dinesh A
authors.initials: DA
authors.lastname: Nagegowda
authors.forename: Florence
authors.initials: F
authors.lastname: Negre-Zakharov
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Huh
authors.forename: Hongli
authors.initials: H
authors.lastname: Luo
authors.forename: Renate
authors.initials: R
authors.lastname: Weizbauer
authors.forename: Tesfaye
authors.initials: T
authors.lastname: Mengiste
authors.forename: Dorothea
authors.initials: D
authors.lastname: Tholl
authors.forename: Natalia
authors.initials: N
authors.lastname: Dudareva
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives / Q000378:metabolism; D000085:Acetates / Q000494:pharmacology; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000469:parasitology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D005247:Feeding Behavior; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D007313:Insecta / Q000472:pathogenicity; D007814:Larva / Q000472:pathogenicity; D009812:Odorants; D054883:Oxylipins / Q000494:pharmacology; D010802:Phylogeny; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology / Q000469:parasitology; D011058:Pollen / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D017386:Sequence Homology, Amino Acid; D014445:Tyrosine Decarboxylase / Q000235:genetics / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism; D014835:Volatilization
chemical_list: D000085:Acetates; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; D055549:Volatile Organic Compounds; C072239:methyl jasmonate; D014445:Tyrosine Decarboxylase; D001142:Aromatic-L-Amino-Acid Decarboxylases; D000079:Acetaldehyde; C013192:phenylacetaldehyde