Heavy metal stress can prime for herbivore-induced plant volatile emission

Department of Botany II, University of Würzburg, Julius-von-Sachs-Platz 3, 97082 Würzburg, Germany.
Plant Cell and Environment (Impact Factor: 5.91). 02/2012; 35(7):1287-98. DOI: 10.1111/j.1365-3040.2012.02489.x
Source: PubMed

ABSTRACT Heavy metals are important pollutants that can severely impact ecological foodwebs. In addition to direct toxic effects, these contaminants have been suggested to disrupt chemical communication channels between plants and insects that rely on volatile organic compounds (VOCs). We investigated how different concentrations of copper (Cu) and cadmium (Cd) stress affect the capacity of Zea mays to synthesize VOCs in the presence and absence of herbivorous insects. Hydroponically grown maize exposed to a high and low concentration of either Cu or Cd showed stunted growth and lower photosynthetic capacities. Herbivores feeding on stressed plants also had attenuated growth rates. Heavy metal treatment alone did not induce VOC emission in maize plants; however, the higher Cu dose was found to prime for enhanced volatile production that can be triggered by caterpillar feeding. Cu stress correlated with increased levels of reactive oxygen species in roots and priming of herbivore-induced jasmonic acid in leaves. Plants challenged with Cd and herbivory did not differ in responses compared with herbivore-damaged controls with no heavy metals added to the substrate. For Cu stress, our results support the 'single biochemical mechanism for multiple stressors' model which predicts overlapping signalling and responses to abiotic and biotic stress factors.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The effects of volatile emissions from plants exposed to individual abiotic and biotic stresses are well documented. However, the influence of multiple stresses on plant photosynthesis and defense responses, resulting in a variety of volatile profiles has received little attention. In this study, we investigated how temperature regimes in the presence and absence of the sucking insect Myzus persicae affected volatile organic compound (VOC) emissions in Arabidopsis over three time periods (0-24, 24-48, and 48-72 h). Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was used to evaluate Arabidopsis VOCs. The results showed that under laboratory conditions, eight volatile classes [alcohols (mainly 2-ethyl-hexan-1-ol), ketone (6-methyl hept-5-en-2-one), esters (mainly (Z)-3-hexenyl acetate), aldehydes (mainly phenylacetaldehyde), isothiocyanates (mainly 4-methylpentyl isothiocyanate), terpenes (mainly (E,E)-alpha-farnesene), nitrile (5-(methylthio) pentanenitrile), and sulfide (dimethyl trisulfide)] were observed on plants exposed to stress combinations, whereas emissions of six volatile classes were observed during temperature stress treatments alone (with the exception of nitriles and sulfides). Aphid density at high temperature combinations resulted in significantly higher isothiocyanate, ester, nitrile, and sulfide proportions. The results of the present study provide an insight into the effects of temperature-aphid interactions on plant volatile emissions.
    Arthropod-Plant Interactions 08/2014; 8(4). DOI:10.1007/s11829-014-9311-6 · 1.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rare earth elements (REEs) at proper concentrations were observed to alleviate heavy metal stress. However, the potential mechanisms are not clear. Thus, the present work focused on the mechanisms of lanthanum (La) ions on the generation and elimination of reactive oxygen species (ROS) production in leaves of rice seedlings hydroponically cultivated in 30 µM cadmium chloride (CdCl2) for two days. Results showed that the decline of O2 · - or H2O2 was attributed not only to the decreased expressions of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases-related gene, protein synthesis, and isozymes, but also to the decrease of xanthine oxidase (XOD), diamine oxidase (DAO), and guaiacol peroxidases (POD) isozymes and activities. Superoxide dismutase (SOD)-, catalase (CAT)- and ascorbate peroxidase (APX)-related genes and isozymes were also differentially upregulated to control ROS accumulation when proper concentrations of La were combined with 30 µM Cd. Based on the results, it may be concluded that La at proper concentrations not only limited the generation of O2 · - and H2O2 from the enzymatic sources, but also promoted the elimination of O2 · - and H2O2 via the up-regulating expressions of antioxidant enzymes-related genes and activities in the rice seedling's leaves under Cd stress. Environ Toxicol Chem © 2014 SETAC
    Environmental Toxicology and Chemistry 07/2014; 33(7). DOI:10.1002/etc.2610 · 2.83 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Several species of the fungus Trichoderma can promote plant health and are widely used as commercial biopesticides. Beneficial effects of this fungus are attributed to various mechanisms such as mycoparasitism, plant-growth promotion, increased stress tolerance and elicitation of induced systemic resistance against pathogens via jasmonic acid/ethylene-dependent pathways. Despite such well-established effects on pathogens, surprisingly little is known about the influence of Trichoderma on plant defences against herbivorous insects. This study investigated whether soil-supplementation of the established biocontrol agent Trichoderma atroviride LU132 affected the performance of oilseed rape (Brassica napus) and the development of Plutella xylostella caterpillars. Furthermore, induction and priming of defence-related phytohormones, genes and secondary metabolites by fungus and herbivore were assessed. Plants colonized by T. atroviride LU132 had significantly larger root and shoot biomass than controls. No effects of fungal inoculation were found on herbivore development. Leaf feeding of the herbivore induced higher jasmonic acid levels, but this was not influenced by fungal treatment. Similarly, the defence-related genes MYC2 and TPI were induced by herbivory but not primed or induced by T. atroviride. Expression of the gene PDF1.2 was repressed by herbivore feeding while no effects on the gene ACO and glucosinolates were observed. We conclude that T. atroviride LU132 has positive effects on the growth of oilseed but it does not enhance above-ground insect defences.
    BioControl 04/2014; 59(2):1-12. DOI:10.1007/s10526-013-9554-7 · 2.25 Impact Factor