Luminescence imaging of leaf damage induced by lipid peroxidation products and its modulation by β‐cyclocitral

Abstract

Lipid peroxidation is a primary event associated with oxidative stress in plants. This phenomenon secondarily generates bioactive and/or toxic compounds such as reactive carbonyl species (RCS), phytoprostanes, and phytofurans, as confirmed here in Arabidopsis plants exposed to photo‐oxidative stress conditions. We analyzed the effects of exogenous applications of secondary lipid oxidation products on Arabidopsis plants by luminescence techniques. Oxidative damage to attached leaves was measured by autoluminescence imaging, using a highly sensitive CCD camera, and the activity of the detoxification pathway, dependent on the transcription regulator SCARECROW‐LIKE 14 (SCL14), was monitored with a bioluminescent line expressing the firefly LUCIFERASE (LUC) gene under the control of the ALKENAL REDUCTASE (AER) gene promoter. We identified 4‐hydroxynonenal (HNE), and to a lesser extent 4‐hydroxyhexenal (HHE), as highly reactive compounds that are harmful to leaves and can trigger AER gene expression, contrary to other RCS (pentenal, hexenal) and to isoprostanoids. Although the levels of HNE and other RCS were enhanced in the SCL14‐deficient mutant (scl14), exogenously applied HNE was similarly damaging to this mutant, its wild‐type parent and a SCL14‐overexpressing transgenic line (OE:SCL14). However, strongly boosting the SCL14 detoxification pathway and AER expression by a pre‐treatment of OE:SCL14 with the signaling apocarotenoid β‐cyclocitral canceled the damaging effects of HNE. Conversely, in the scl14 mutant, the effects of β‐cyclocitral and HNE were additive, leading to enhanced leaf damage. These results indicate that the cellular detoxification pathway induced by the low‐toxicity β‐cyclocitral targets highly toxic compounds produced during lipid peroxidation, reminiscent of a safener‐type mode of action.

Lipid Peroxide-Derived Reactive Carbonyl Species as Mediators of Oxidative Stress and Signaling

“…Gas chromatography-mass spectrometry (GC-MS) is also used for determining RCS and oxylipin carbonyls (Michalski et al, 2008). The exposure of A. thaliana plants to high light (1,500 µmol photons m −2 s −1 ) at low temperature (7 • C) for 24 h increased the levels of 4-hydroxy-2-hexenal (HHE), HNE, and hexenal (Rac et al, 2021). The C3-C17 volatile compounds emitted during wounding were determined quantitatively in the leaves of five tropical crops (Portillo-Estrada et al, 2021).…”

Imaging of Lipid Peroxidation-Associated Chemiluminescence in Plants: Spectral Features, Regulation and Origin of the Signal in Leaves and Roots

“…In particular, alkenal reductase (AER) is one such enzyme which targets several lipid oxidation metabolites with a particular affinity for hydroxynonenal (HNE) [ 40 , 41 ]. Figure 10 a shows the effect of wounding on AER expression using the pAER:Luc line that expresses the LUC gene, coding for the luciferase enzyme, under the control of the AER promoter [ 18 ]. Spraying pAER:Luc plants with luciferin induces a luminescence signal if luciferase is present, i.e., under conditions promoting AER expression.…”

“…The SCL14-TGA system governs the expression of various detoxifying enzymes, such as reductases, dehydrogenases and glutathione transferases, which play an important role in the metabolization of exogenous or endogenous toxic compounds [ 43 , 44 , 57 ]. Lipid oxidation-derived metabolites are among the targets of this pathway [ 18 ]. Therefore, we can propose that some of the lipid peroxidation products that emit photons or whose decomposition generates light-emitting species are targeted by the SCL14-dependent detoxification pathway.…”

“…Arabidopsis plants (Arabidopsis thaliana, ecotype Col-0) were grown for 4–5 weeks in a phytotron in the Phytotec platform of the BIAM Institute (CEA/Cadarache) under controlled conditions: temperature, 24/20 °C (day/night); photon flux density, 120 µmol photons m −2 s −1 ; photoperiod, 8 h; air humidity, 55%. The following mutant lines were also used: the variegated thf1 mutant [ 16 ], the lipoxygenase2-deficient lox2-1 mutant [ 17 ] and the transgenic luminescent line pAER:LUC [ 18 ]. Pea seeds (Pisum sativum) were germinated on wet filter paper in Petri dishes for 3 d. Pea, rather than Arabidopsis, was used for root analyses because Arabidopsis roots are too small to be easily injured with a scalpel and for their luminescence to be easily measured with this treatment.…”

Wheat Oxylipins in Response to Aphids, CO2 and Nitrogen Regimes

“…It develops as a result of the overproduction and accumulation of ROS [ 25 ]. PhytoPs and PhytoFs are both an oxidation index of plant lipids [ 26 , 27 ], and a biomarker for quality control of plant food products during manufacturing and storage [ 16 ]. Processing techniques, such as roasting or frying and storage at different temperatures, were found to affect the generation of PhytoPs in food products such as sea buckthorn, vegetables, olives, grape must, almond kernels, nuts and pistachios [ 20 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ].…”