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: 6.96).
02/2012; 35(7):1287-98. DOI: 10.1111/j.1365-3040.2012.02489.x
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.
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- "Changes in leaf JA levels were determined by using a modification of the vapour-phase extraction method (Winter et al., 2012) developed by Schmelz et al. (2004). After 3 days of exposure to salt stress each plant was transferred to a single plastic vessel containing 120 ml of the respective hydroponic solution. "
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ABSTRACT: In nature, plants are often exposed to multiple stress factors at the same time. The effects of single biotic or abiotic stresses on plant metabolism are well documented but how plants respond to a combination of these is little researched. Here we studied the effects of high salinity and herbivory on levels of secondary compounds and gene expression associated with defences against insects. Hydroponically grown maize plants were subjected to sodium chloride (1, 50, 100 mM NaCl) and/or damage by caterpillars of Spodoptera exigua. Salt-stressed plants showed stunted growth, reduced chlorophyll fluorescence and enhanced levels of reactive oxygen species and 1,4-benzoxazin-3-one aglycones (aBX). Herbivory induced higher transcript levels of the Zm-Bx1 gene involved in aBX biosynthesis and of the Zm-SerPIN gene coding for a serine proteinase inhibitor which might affect plant feeding insects. Herbivory also triggered the emission of volatile organic compounds (VOCs) that are attractive signals for parasitoids and predators and thus regarded as an indirect defence. Herbivore-induced metabolites were differentially affected in salt-stressed plants. High salinity resulted in transient priming of jasmonic acid while aBX levels were reduced in double-stressed plants. Salt stress led to lower herbivore-induced VOC emission per plant but not per unit biomass. However, quantitative shifts in individual compounds were found in both cases. Our study confirms the notion that combined stresses produce a unique phenotype that cannot be derived from single-stress effects. The ecological implications of these changes for organisms from different trophic levels and for plant fitness remain to be tested.
Environmental and Experimental Botany 09/2015; 122. DOI:10.1016/j.envexpbot.2015.09.007
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ABSTRACT: Volatile compounds emitted by plants in response to herbivory serve as important cues within and between trophic levels, and as cues over more than two trophic levels, such as in the attraction of enemies of herbivores. However, many of the volatiles elicited by herbivory are highly reactive with key atmospheric
pollutants, implying that the signal is communicated over increasingly shorter distances with increasing pollutant concentrations in the atmosphere. Thus, polluted atmospheres can importantly alter the multitrophic interactions between trees, herbivores and herbivore enemies. This chapter highlights the alterations in multitrophic interactions and resulting modifications in plant fitness in polluted atmospheres.
Biology, Controls and Models of Tree Volatile Organic Compound Emissions, Tree Physiology volume 5 edited by U¨ . Niinemets, R.K. Monson, 01/2013: chapter Multitrophic Signalling in Polluted Atmospheres: pages 285-314; Springer., ISBN: 978-94-007-6606-8
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ABSTRACT: Iron (Fe) homeostasis is essential for life and has been intensively investigated for dicots, while our knowledge for species in the Poaceae is fragmentary. This study presents the first proteome analysis (LC-MS/MS) of plasma membranes isolated from roots of 18-days old maize (Zea mays L.). Plants were grown under low and high Fe conditions in hydroponic culture. In total, 227 proteins were identified in control plants, whereas 204 proteins were identified in Fe deficient plants and 251 proteins in plants grown under high Fe conditions. Proteins were sort by functional classes, most of the identified proteins were classified as signalling proteins. A significant number of PM-bound redox proteins could be identified including quinone reductases, heme and copper-containing proteins. Most of these components were constitutive, others could hint at an involvement of redox signalling and redox homeostasis by change in abundance. Energy metabolism and translation seem to be crucial in Fe homeostasis. The response to Fe deficiency includes proteins involved in development, whereas membrane remodelling and assembly and/or repair of Fe-S clusters is discussed for Fe toxicity. The general stress response appears to involve proteins related to oxidative stress, growth regulation, an increased rigidity and synthesis of cell walls and adaption of nutrient uptake and/or translocation.
Journal of proteomics 01/2013; 91. DOI:10.1016/j.jprot.2013.01.006
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