title: Overexpression of the PAP1 transcription factor reveals a complex regulation of flavonoid and phenylpropanoid metabolism in Nicotiana tabacum plants attacked by Spodoptera litura.
abstract: Anthocyanin pigments and associated flavonoids have demonstrated antioxidant properties and benefits for human health. Consequently, current plant bioengineers have focused on how to modify flavonoid metabolism in plants. Most of that research, however, does not consider the role of natural biotic stresses (e.g., herbivore attack). To understand the influence of herbivore attack on the metabolic engineering of flavonoids, we examined tobacco plants overexpressing the Arabidopsis PAP1 gene (encoding an MYB transcription factor), which accumulated anthocyanin pigments and other flavonoids/phenylpropanoids. In comparison to wild-type and control plants, transgenic plants exhibited greater resistance to Spodoptera litura. Moreover, herbivory suppressed the PAP1-induced increase of transcripts of flavonoid/phenylpropanoid biosynthetic genes (e.g., F3H) and the subsequent accumulation of these genes' metabolites, despite the unaltered PAP1 mRNA levels after herbivory. The instances of down-regulation were independent of the signaling pathways mediated by defense-related jasmonates but were relevant to the levels of PAP1-induced and herbivory-suppressed transcription factors, An1a and An1b. Although initially F3H transcripts were suppressed by herbivory, after the S. litura feeding was interrupted, F3H transcripts increased. We hypothesize that in transgenic plants responding to herbivory, there is a complex mechanism regulating enriched flavonoid/phenylpropanoid compounds, via biotic stress signals.
authors.affiliation: Department of Biological Science & Technology, Faculty of Industrial Science & Technology, Tokyo University of Science, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Mitsunami
authors.affiliation: Iwate Biotechnology Research Center, Kitakami, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishihara
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki, Japan.
authors.forename: Ivan
authors.initials: I
authors.lastname: Galis
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki, Japan.
authors.forename: Kabir Md
authors.initials: KM
authors.lastname: Alamgir
authors.affiliation: Institute of Plant Science and Resources, Okayama University, Kurashiki, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hojo
authors.affiliation: Iwate Biotechnology Research Center, Kitakami, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Iwate Biotechnology Research Center, Kitakami, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Sasaki
authors.affiliation: Proteo-Science Center, Ehime University, Matsuyama, Japan.
authors.forename: Keichiro
authors.initials: K
authors.lastname: Nemoto
authors.affiliation: Proteo-Science Center, Ehime University, Matsuyama, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sawasaki
authors.affiliation: Department of Biological Science & Technology, Faculty of Industrial Science & Technology, Tokyo University of Science, Tokyo, Japan.
authors.forename: Gen-ichiro
authors.initials: G
authors.lastname: Arimura
mesh_terms: D000818:Animals; D000872:Anthocyanins / Q000737:chemistry / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism; D015536:Down-Regulation; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D060434:Herbivory; D007814:Larva / Q000502:physiology; D054883:Oxylipins / Q000378:metabolism; D000073718:Pancreatitis-Associated Proteins; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism / Q000469:parasitology; D020005:Propanols / Q000737:chemistry / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018411:Spodoptera / Q000254:growth & development; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D005419:Flavonoids; D054883:Oxylipins; D000073718:Pancreatitis-Associated Proteins; D010940:Plant Proteins; D020005:Propanols; D012333:RNA, Messenger; D014157:Transcription Factors; C502612:AT1G56650 protein, Arabidopsis; C000612141:REG3A protein, human; C439395:1-phenylpropanol; C011006:jasmonic acid