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Constitutive and MeJA-induced terpenes in Pinus pinaster and Pinus radiata in relation to Hylobius abietis
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. (AKBK/Ecological Chemistry Group)ORCID iD: 0000-0003-2867-2004
Grupo de Xenetica e Ecoloxía da Resistencia en Coníferas, Misión Biológica de Galicia (MBG-CSIC), Pontevedra, Spain.
Grupo de Xenetica e Ecoloxía da Resistencia en Coníferas, Misión Biológica de Galicia (MBG-CSIC), Pontevedra, Spain.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. (AKBK/Ecological Chemistry Group)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The feeding preference of the pine weevil to Maritime pine (Pinus pinaster Ait.) and Monterey pine (Pinus radiata D. Don) differ in laboratory tests and in the field: Can this be explained by the volatile compounds released by the seedlings? Understanding the interaction between the chemical defenses of young pines and feeding preferences of the pine weevil (Hylobius abietis (L.)) may improve protection methods of conifer seedlings in Europe and Asia. In order to increase the resistance of seedlings of P. pinaster and P. radiata, these were treated with the chemical elicitor methyl jasmonate (MeJA). The effects of the MeJA treatments on the amounts and composition of volatile terpenes in tissues (needles and phloem) were investigated by extracting these in hexane, whereafter the volatile constituents of the extracts were separated and identified by gas chromatography-mass spectrometry (GC-MS). In addition, the most abundant monoterpenes (α-pinene and β-pinene) were separated on a chiral column in their enantiomers. Already at the lowest concentration of MeJA treatment, 5 mM, the amounts of volatile terpenes in the needles of P. radiata increased and the seedling heights were reduced. In P. pinaster, on the other hand, no effect from the MeJA treatment was observed on the total volatile terpenes in the needles, and only at the strongest MeJA concentration, the seedling heights were affected. In the phloem of P. pinaster the composition of volatile contents, changed after MeJA treatment, showing a reduction in the (+)-α-pinene. In contrast, the amounts of (+)-α-pinene increased in P. radiata. In a previous study, controls and MeJA-treated pine seedlings, from the same MeJA treatment batches as in this study, were subjected to a field trial. In the field, the pine weevils preferred the seedlings of P. radiata over those of P. pinaster. We propose that the differences in induction of (+)-α-pinene may be important for explaining the differences in pine weevil feeding preferences.

Keyword [en]
Pinus pinaster, Pinus radiata, Hylobius abietis, needles, phloem, monoterpenes, methyl jasmonate
National Category
Organic Chemistry Analytical Chemistry Other Chemistry Topics Ecology
Research subject
Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-183265OAI: oai:DiVA.org:kth-183265DiVA: diva2:908923
Funder
Swedish Foundation for Strategic Research , Parasite Resistant Trees
Note

QS 2016

Available from: 2016-03-03 Created: 2016-03-03 Last updated: 2016-03-04Bibliographically approved
In thesis
1. Effects of methyl jasmonate on chemical defenses of conifer seedlings in relation to feeding by Hylobius abietis
Open this publication in new window or tab >>Effects of methyl jasmonate on chemical defenses of conifer seedlings in relation to feeding by Hylobius abietis
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The chemical elicitor methyl jasmonate (MeJA) could replace insecticides in Europe and Asia for protection of young conifers against the pine weevil (Hylobius abietis). This thesis mainly focuses on the effects of MeJA treatment on chemical defenses of conifers from seedling batches with documented field resistance. Tissues of three pine species and one spruce species, with various treatments, were here extracted in hexane, whereafter volatile contents of tissues were separated and analyzed by 2D GC-MS.

Induced responses of seedlings of Maritime pine (Pinus pinaster) and Monterey pine (Pinus radiata) to the folivore pine processionary (Thaumetopoea pityocampa), and the phloem-feeder H. abietis, have been studied. Amounts of mono- and sesqui-terpenes (and also non-volatile resin) in conifer tissues (needles and phloem) were less induced by T. pityocampa than by H. abietis.

The MeJA-treated seedlings of Scots pine (Pinus sylvestris) changed their composition of phloem monoterpenes (induction of (-)-β-pinene), and were better protected in field than the seedlings of Norway spruce (Picea abies), which increased their total amounts of monoterpenes. Orientation bioassays with H. abietis showed deterrent effects of (-)-β-pinene, (+)-3-carene, (-)-bornyl acetate and 1,8-cineole. Conversely, (-)-α-pinene (induced in P. abies but not in P. sylvestris) was non-deterrent.

MeJA-treated seedlings fed on by H. abietis contained higher amounts of the H. abietis antifeedant 2-phenylethanol, in tissues and emissions. Phloem of control seedlings instead induced the (+)-α-pinene, which is one of the enantiomers of the H. abietis attractant α-pinene.

In response to MeJA treatment, the relative amounts of the (+)-α-pinene increased in the phloem of  P. radiata, while it decreased in P. pinaster phloem. The preference of H. abietis in the field for P. radiata before P. pinaster may be explained by these changes in enantiomers of the H. abietis attractant α-pinene.

Abstract [sv]

Barrträd är viktiga för skogsindustrin. I Sverige består 57% av ytan av produktiv skogsmark, och av dessa träd utgörs 80% av gran och tall. Som försvar mot insekter och sjukdomar, producerar barrträden kådämnen. För unga barrträd i Europa och Asien är snytbaggen (Hylobius abietis) en allvarlig skadegörare, som orsakar skogsnäringen stora kostnader. För att skydda små gran- och tallplantor före utplanteringen, skulle växthormonet metyljasmonat (MeJA) kunna användas.

I denna avhandling har effekter av MeJA-behandling och insektsangrepp undersökts på de två viktigaste barrträden i Sverige, tall och gran (Pinus sylvestris och Picea abies) och på två arter i medelhavsområdet (Pinus radiata och Pinus pinaster). De kemiska försvarsämnena i barrträd har analyserats för att utvärdera effekterna av MeJA-behandling. Vävnader från barrträd med olika behandling har extraherats i organiska lösningsmedel och dofterna från plantorna har insamlats genom fastfas-mikroextraktion. De flyktiga ämnena har separerats och identifierats med hjälp av gaskromatografi och masspektrometri (GC-MS). Dessutom har optiskt aktiva doftämnen separerats med hjälp av en tvådimensionell GC-MS.

Plantornas olika försvarsreaktioner har studerats vid angrepp av snytbaggen, som är en floemätare, och av tallfjärilslarv (Thaumetopoea pityocampa), som huvudsakligen äter barr. De lättflyktiga ämnena (mono- och seskviterpener) och de icke-flyktiga ämnena (kådsyror) ökade mer i stam och barr från angrepp av H. abietis än av T. pityocampa.

Sammansättning av monoterpener ändrades i de MeJA-behandlade tallplantorna i Sverige, specifikt ökade (-)-β-pinene i stamfloemet. Tallplantorna var bättre skyddade i fält än granplantorna, där den totala mängden monoterpener ökade.

(-)-β-Pinene, (+)-3-carene, (-)-bornyl acetate och 1,8-cineole visade sig ha en negativ effekt på snytbaggens orientering mot talldoft i orienteringstester. En av monoterpenerna, (-)-α-pinene, som av MeJA-behandlingen inducerats i granen, men inte i tallen, hade ingen negativ effekt på snytbaggen.

MeJA-behandlade tallplantor som angripits av snytbaggen, innehöll större mängder av snytbagge-äthämmaren 2-fenyletanol, både i vävnader och i emissioner. Stam från kontrollplantor inducerade istället (+)-α-pinene, vilken är en av de optiska isomererna av snytbagge-attrahenten α-pinene.

För de spanska arterna, som svar på MeJA-behandling, ökade de lättflyktigaste terpenerna i barren hos P. radiata men inte hos P. pinaster, vilken redan innehöll en hög terpenhalt. De relativa mängderna av (+)-α-pinene ökade också i stammen hos P. radiata, medan de minskade i P. pinaster. I fält väljer snytbaggen att gå till P. radiata- framför P. pinaster-plantor, vilket kan vara kopplat till de skillnader i α-pinene-isomerer, vilka här har observerats.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xii, 49 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:7
Keyword
Pinaceae, Pinus pinaster, Pinus radiata, Pinus sylvestris, Picea abies, Thaumetopoea pityocampa, Hylobius abietis, Needles, Phloem, Feeding, Vaccination, Priming, Methyl jasmonate, Aromatics, Phenolics, Monoterpenes, Pinaceae, Pinus pinaster, Pinus radiata, Pinus sylvestris, Picea abies, Thaumetopoea pityocampa, Hylobius abietis, Barr, Floem, Ätning, Vaccinering, Metyljasmonat, Aromater, Fenoler, Monoterpener
National Category
Other Chemistry Topics Organic Chemistry Analytical Chemistry Ecology
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-183268 (URN)978-91-7595-863-7 (ISBN)
Public defence
2016-03-30, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Foundation for Strategic Research , Parasite Resistant Trees
Note

QC 20160304

Available from: 2016-03-04 Created: 2016-03-03 Last updated: 2016-04-01Bibliographically approved

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