title: Activation of the Phenylpropanoid pathway in Nicotiana tabacum improves the performance of the whitefly Bemisia tabaci via reduced jasmonate signaling.
abstract: BACKGROUND
  Phloem-feeding insects can manipulate plant-induced resistance and are able to suppress effective jasmonic acid/ethylene (JA/ET) defenses by the induction of inefficient salicylic acid (SA) based responses. As a result, activation of the phenylpropanoid biosynthesis pathway in transgenic plants is anticipated to cause complex interactions between phloem-feeding insects and their host plants due to predicted contradiction between two defense forces: the toxicity of various phenylpropanoids and the accumulation of SA via a branch of the activated pathway.
  
  
  RESULTS
  Here, we investigated the effect of activating the phenylpropanoids pathway in Nicotiana tabacum, by over-expression of the PAP1 transcription factor, on the whitefly Bemisia tabaci, a phloem-feeding insect model. Our performance assays indicated that the over-expression made the transgenic plants a more suitable host for B. tabaci than wild-type (WT) plants, although these plants accumulated significantly higher levels of flavonoids. Transcription analyses of indicator genes in the SA (PR1a) and JA/ET (ERF1, COI1 and AOC) pathways followed by quantification of the SA and JA hormone levels, indicated that B. tabaci infestation periods longer than 8 hours, caused higher levels of activity of SA signaling in transgenic plants and higher levels of JA/ET signaling in WT plants.
  
  
  CONCLUSIONS
  Taken together, these results emphasize the important role JA/ET-induced defenses play in protecting plants from successful infestation by B. tabaci and likely other phloem-feeding insects. It also indicates the necessity of phloem feeders to suppress these defenses for efficient utilization of plant hosts. Our data also indicate that the defensive chemistry produced by the phenylpropanoids pathway has only a minor effect on the insect fitness.
authors.affiliation: Department of Entomology, the Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Michal
authors.initials: M
authors.lastname: Alon
authors.forename: Osnat
authors.initials: O
authors.lastname: Malka
authors.forename: Galit
authors.initials: G
authors.lastname: Eakteiman
authors.forename: Moshe
authors.initials: M
authors.lastname: Elbaz
authors.forename: Michal
authors.initials: M
authors.lastname: Moyal Ben Zvi
authors.forename: Alexander
authors.initials: A
authors.lastname: Vainstein
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
mesh_terms: D000818:Animals; D003517:Cyclopentanes / Q000378:metabolism*; D005260:Female; D015870:Gene Expression; D006430:Hemiptera / Q000502:physiology*; D060434:Herbivory; D008297:Male; D053858:Metabolic Networks and Pathways; D054883:Oxylipins / Q000378:metabolism*; D000073718:Pancreatitis-Associated Proteins; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D020005:Propanols / Q000378:metabolism*; D015398:Signal Transduction; D014026:Nicotiana / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D000073718:Pancreatitis-Associated Proteins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D020005:Propanols; C000612141:REG3A protein, human; D014157:Transcription Factors; C439395:1-phenylpropanol; C011006:jasmonic acid