Abstract

Over the last decades, post‐illumination bursts (PIBs) of isoprene, acetaldehyde and green leaf volatiles (GLVs) following rapid light‐to‐dark transitions have been reported for a variety of different plant species. However, the mechanisms triggering their release still remain unclear. Here we measured PIBs of isoprene‐emitting (IE) and isoprene non‐emitting (NE) grey poplar plants grown under different climate scenarios (ambient control and three scenarios with elevated CO2 concentrations: elevated control, periodic heat and temperature stress, chronic heat and temperature stress, followed by recovery periods). PIBs of isoprene were unaffected by elevated CO2 and heat and drought stress in IE, while they were absent in NE plants. On the other hand, PIBs of acetaldehyde and also GLVs were strongly reduced in stress‐affected plants of all genotypes. After recovery from stress, distinct differences in PIB emissions in both genotypes confirmed different precursor pools for acetaldehyde and GLV emissions. Changes in PIBs of GLVs, almost absent in stressed plants and enhanced after recovery, could be mainly attributed to changes in lipoxygenase activity. Our results indicate that acetaldehyde PIBs, which recovered only partly, derive from a new mechanism in which acetaldehyde is produced from methylerythritol phosphate pathway intermediates, driven by deoxyxylulose phosphate synthase activity.

Highlights

  • Acetaldehyde and compounds commonly referred to as green leaf volatiles [GLVs, different C6 compounds originating from the lipoxygenase (LOX) pathway, such as E-2-hexenal, Z-3-hexenal and Z-3-hexenol], are among the most prominent

  • Our experiments showed that post-illumination bursts’ (PIBs) of acetaldehyde, ethanol and GLVs are potential markers for the heat and drought stress status of poplar plants

  • While PIBs of acetaldehyde were lower in plants recovering from HDS in respect to the corresponding control plants, PIBs of GLVs were enhanced

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Summary

Introduction

Green leaf volatiles are often released in considerable amounts by plants under abiotic stress and herbivory or pathogen infection (Loreto & Schnitzler 2010; Holopainen & Gershenzon 2010; Scala et al 2013). In the algae Eremosphaera viridis, a quick light-to-dark transition leads to a short-term (1–3 min) acidification of the cytosol (Bethmann et al 1998) This effect could trigger the activation of LOX, which has its activity optimum at pH values of 6.3 and 4.5 (Hatanaka 1993). Fast dark-to-light transitions lead to an alkalization (Bethmann et al 1998), which might explain why fast, repeated light-to-dark transitions do not cause PIBs, as has been shown previously using grey poplar leaves (Graus et al 2004)

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