Stomatal constraints may affect emission of oxygenated monoterpenoids

 

 

Stomatal Constraints May Affect Emission of Oxygenated Monoterpenoids from the Foliage of Pinus pinea

by Niinemets ÜReichstein M.Staudt M.Seufert G., Tenhunen J. D. (2002)

Ülo Niinemets, Markus ReichsteinMichael StaudtGünther SeufertJohn D. Tenhunen,

Department of Plant Physiology, Institute of Molecular and Cell Biology, University of Tartu, Riia 23, EE 51010 Tartu, Estonia (Ü.N.);

Department of Plant Ecology, University of Bayreuth, D–95440 Bayreuth, Germany (M.R., J.D.T.);

Joint Research Centre of the European Commission, Environment Institute, 21020 Ispra (Va), Italy (M.S., G.S.)

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in Plant Physiol. 130(3): 1371–1385 – doi:  10.1104/pp.009670 – 

Abstract/FREE Full TextGoogle Scholar

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC166656/

http://www.plantphysiol.org/content/130/3/1371

ABSTRACT

Dependence of monoterpenoid emission and fractional composition on stomatal conductance (GV) was studied in Mediterranean conifer Pinus pinea, which primarily emits limonene and trans-β-ocimene but also large fractions of oxygenated monoterpenoids linalool and 1,8-cineole.

Strong decreases in GV attributable to diurnal water stress were accompanied by a significant reduction in total monoterpenoid emission rate in midday. However, various monoterpenoids responded differently to the reduction in GV, with the emission rates of limonene and trans-β-ocimene being unaffected but those of linalool and 1,8-cineole closely following diurnal variability in GV.

A dynamic emission model indicated that stomatal sensitivity of emissions was associated with monoterpenoid Henry’s law constant (H, gas/liquid phase partition coefficient). Monoterpenoids with a large H such as trans-β-ocimene sustain higher intercellular partial pressure for a certain liquid phase concentration, and stomatal closure is balanced by a nearly immediate increase in monoterpene diffusion gradient from intercellular air-space to ambient air.

The partial pressure rises also in compounds with a low H, but more than 1,000-fold higher liquid phase concentrations of linalool and 1,8-cineole are necessary to increase intercellular partial pressure high enough to balance stomatal closure. The system response is accordingly slower, and the emission rates may be transiently suppressed by low GV.

Simulations further suggested that linalool and 1,8-cineole synthesis rates also decreased with decreasing GV, possibly as the result of selective inhibition of various monoterpene synthases by stomata.

We conclude that physicochemical characteristics of volatiles not only affect total emission but also alter the fractional composition of emitted monoterpenoids.

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Key role of stomatal conductance in controlling ozone uptake, leaf injury and volatile release

 

Ozone-induced foliar damage and release of stress volatiles is highly dependent on stomatal openness and priming by low-level ozone exposure in Phaseolus vulgaris

by Li S., Harley P. C., Niinemets Ü. (2017)

  1. Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, Estonia
  2. Estonian Academy of Sciences, Tallinn, Estonia

Shuai Li,

Peter C. Harley,

Ülo Niinemets

in Plant, Cell & Environment – doi: 10.1111/pce.13003. –

http://onlinelibrary.wiley.com/doi/10.1111/pce.13003/abstract

Abstract

Acute ozone exposure triggers major emissions of volatile organic compounds (VOC), but quantitatively, it is unclear how different ozone doses alter the start and the total amount of these emissions, and the induction rate of different stress volatiles. It is also unclear whether priming (i.e., pre-exposure to lower O3 concentrations) can modify the magnitude and kinetics of volatile emissions.

We investigated photosynthetic characteristics and VOC emissions in Phaseolus vulgaris following acute ozone exposure (600 nmol mol-1 for 30 min) under illumination and in darkness and after priming with 200 nmol mol-1 O3 for 30 min.

Methanol and lipoxygenase (LOX) pathway product emissions were induced rapidly, followed by moderate emissions of methyl salicylate (MeSA).

Stomatal conductance prior to acute exposure was lower in darkness and after low O3 priming than in light and without priming. After low O3 priming, no MeSA and lower LOX emissions were detected under acute exposure.

Overall, maximum emission rates and the total amount of emitted LOX products and methanol were quantitatively correlated with total stomatal ozone uptake.

These results indicate that different stress volatiles scale differently with ozone dose and highlight the key role of stomatal conductance in controlling ozone uptake, leaf injury and volatile release.