Does egg deposition by herbivorous pine sawflies affect transcription of sesquiterpene synthases in pine?
Scots pine (Pinus sylvestris; Pinaceae, Pinales) is known to defend against egg deposition by herbivorous sawflies by changing its terpenoid volatile blend. The oviposition-induced pine odor attracts egg parasitoids that kill the sawfly eggs. Here, we investigated whether sawfly egg deposition activates genes encoding pine terpene synthases by extracting mRNA from oviposition-induced P. sylvestris. Three new sesquiterpene synthases, PsTPS 1, PsTPS 2, and PsTPS 3, were isolated that were shown on heterologous expression in Escherichia coli to produce (E)-beta-caryophyllene and alpha-humulene (PsTPS 1), 1(10),5-germacradiene-4-ol (PsTPS 2), and longifolene and alpha-longipinene (PsTPS 3) as their principal products. Quantitative RT-PCR analyses revealed that transcript levels of PsTPS 1 and PsTPS 2 were significantly higher in oviposition-induced twigs that were attractive to the parasitoids than in non-attractive, artificially damaged twigs. Thus, our results demonstrate a specific transcription response to egg deposition, distinct from that caused by artificial wounding. Transcripts of PsTPS 3 did not change in response to egg deposition. The transcript levels of PsTPS 1, PsTPS 2, and PsTPS 3 were also determined in relation to time after egg deposition, since pine odor is attractive to the parasitoid only 72 h after egg deposition. Transcription rates of PsTPS 1 and PsTPS 2 were significantly enhanced only 72 h after egg deposition, thus matching the timing of odor attractiveness, while for PsTPS 3, enhanced transcription was not detected at any time period studied after egg deposition. The ecological significance of the oviposition-induced increase of sesquiterpene synthase transcripts is discussed.
Köpke
Diana
D
Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knöll-Str. 8, 07745, Jena, Germany.
Schröder
Roland
R
Fischer
Hanna M
HM
Gershenzon
Jonathan
J
Hilker
Monika
M
Schmidt
Axel
A
D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017753:Ecosystem; D005247:Feeding Behavior; D008401:Gas Chromatography-Mass Spectrometry; D018506:Gene Expression Regulation, Plant; D006927:Hymenoptera / Q000502:physiology*; D008969:Molecular Sequence Data; D010058:Oviposition / Q000502:physiology*; D010802:Phylogeny; D028223:Pinus / Q000201:enzymology* / Q000235:genetics* / Q000469:parasitology; D018515:Plant Leaves / Q000469:parasitology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D012717:Sesquiterpenes / Q000032:analysis / Q000737:chemistry; D013997:Time Factors; D014158:Transcription, Genetic
D012333:RNA, Messenger; D012717:Sesquiterpenes; D019883:Alkyl and Aryl Transferases; C108877:terpene synthase