title: Growth regulating properties of isoprene and isoprenoid-based essential oils.
abstract: Essential oils have growth regulating properties comparable to the well-documented methyl jasmonate and may be involved in localized and/or airborne plant communication. Aromatic plants employ large amounts of resources to produce essential oils. Some essential oils are known to contain compounds with plant growth regulating activities. However, the potential capacity of essential oils as airborne molecules able to modulate plant growth/development has remained uninvestigated. Here, we demonstrate that essential oils from eight taxonomically diverse plants applied in their airborne state inhibited auxin-induced elongation of Pisum sativum hypocotyls and Avena sativa coleoptiles. This response was also observed using five monoterpenes commonly found in essential oils as well as isoprene, the basic building block of terpenes. Upon transfer to ambient conditions, A. sativa coleoptiles resumed elongation, demonstrating an antagonistic relationship rather than toxicity. Inclusion of essential oils, monoterpenes, or isoprene into the headspace of culture vessels induced abnormal cellular growth along hypocotyls of Arabidopsis thaliana. These responses were also elicited by methyl jasmonate (MeJA); however, where methyl jasmonate inhibited root growth essential oils did not. Gene expression studies in A. thaliana also demonstrated differences between the MeJA and isoprenoid responses. This series of experiments clearly demonstrate that essential oils and their isoprenoid components interact with endogenous plant growth regulators when applied directly or as volatile components in the headspace. The similarities between isoprenoid and MeJA responses suggest that they may act in plant defence signalling. While further studies are needed to determine the ecological and evolutionary significance, the results of this study and the specialized anatomy associated with aromatic plants suggest that essential oils may act as airborne signalling molecules.
authors.affiliation: Department of Plant Agriculture, Gosling Research Institute for Plant Preservation, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Andrew Maxwell P
authors.initials: AM
authors.lastname: Jones
authors.affiliation: Department of Plant Agriculture, Gosling Research Institute for Plant Preservation, University of Guelph, Guelph, ON, N1G 2W1, Canada.
authors.forename: Mukund R
authors.initials: MR
authors.lastname: Shukla
authors.affiliation: Department of Plant Agriculture, Gosling Research Institute for Plant Preservation, University of Guelph, Guelph, ON, N1G 2W1, Canada.|Department of Horticulture, Faculty of Agriculture, Damanhour University, Al-Gomhuria St., PO Box 22516, Damanhour, Al-Behira, Egypt.
authors.forename: Sherif M
authors.initials: SM
authors.lastname: Sherif
authors.affiliation: British Columbia Institute of Technology, Burnaby, BC, V5G 3H2, Canada.
authors.forename: Paula B
authors.initials: PB
authors.lastname: Brown
authors.affiliation: Department of Plant Agriculture, Gosling Research Institute for Plant Preservation, University of Guelph, Guelph, ON, N1G 2W1, Canada. psaxena@uoguelph.ca.
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Saxena
mesh_terms: D000085:Acetates / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D018554:Avena / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D002070:Butadienes / Q000494:pharmacology; D028527:Cuminum / Q000737:chemistry*; D003517:Cyclopentanes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D045782:Hemiterpenes / Q000494:pharmacology; D018546:Hypocotyl / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D007210:Indoleacetic Acids / Q000378:metabolism; D009822:Oils, Volatile / Q000494:pharmacology*; D054883:Oxylipins / Q000494:pharmacology; D018532:Pisum sativum / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D010420:Pentanes / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010938:Plant Oils / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000187:drug effects; D013729:Terpenes / Q000494:pharmacology
chemical_list: D000085:Acetates; D002070:Butadienes; D003517:Cyclopentanes; D045782:Hemiterpenes; D007210:Indoleacetic Acids; D009822:Oils, Volatile; D054883:Oxylipins; D010420:Pentanes; D010937:Plant Growth Regulators; D010938:Plant Oils; D013729:Terpenes; C005059:isoprene; C072239:methyl jasmonate
keywords: Airborne signalling; Essential oils; Isoprene; Terpenoids