Acrolein is formed from trienoic fatty acids in chloroplast: A targeted metabolomics approach

Abstract

Aldehydes and ketones produced from lipid peroxides (oxylipin carbonyls) exhibit a variety of biological activities ranging from the induction of defense genes to the irreversible damage to cells. Short oxylipin carbonyls such as acrolein and (E)-2-pentenal are responsible for tissue injury under environmental stress, but their production mechanism remains unclear. In this study, we elucidated the source fatty acids of short oxylipin carbonyls in leaves. We first established a comprehensive analysis of oxylipin carbonyls for quantitation and structural estimation. Carbonyls were extracted from rosette leaves of Arabidopsis thaliana, derivatized with 2,4-dinitrophenylhydrazine and separated with a reverse-phase HPLC equipped with a photodiode array detector and an Fourier transform ion cyclotron resonance mass spectrometer. Thirty-three distinct carbonyls were detected, in which 19 species were identified on the MS/MS spectrum. Using this analysis system, we compared the carbonyl composition in the leaves between two A. thaliana lines that have different fatty acid composition. The mutant fad7fad8, which lacks the biosynthesis of trienoic fatty acids in the plastid, contained significantly lower amounts of malondialdehyde, acrolein and (E)-2-pentenal and higher amounts of acetone, 3-pentanone, and n-hexanal than the wild type Col-0. This difference in the carbonyl composition agreed with the oxidative degradation of dienoic and trienoic fatty acids in vitro, showing that similar non-enzymatic reactions occur in the thylakoid membrane. Consideration of the formation mechanism of acrolein from trienoic fatty acid suggests that membrane lipids in chloroplasts are constitutively oxidized by singlet oxygen.

Suppression of Chloroplastic Alkenal/One Oxidoreductase Represses the Carbon Catabolic Pathway in Arabidopsis Leaves during Night

“…Based on these reports, lipid-derived RCS diffused in plant cells might modify the gene expression network, which is not analyzed in this study, and cause the decrease of carbon utilization during the night and the growth retardation in aor mutants. Combining the results of Mano et al (2014a) and our study, we concluded that chloroplasts are a major production site of lipid-derived RCS and might be an initiator for lipidderived RCS-dependent signaling cascades in plant cells. Accordingly, further intensive studies are required to elucidate the molecular targets of lipidderived RCS, especially the receptors of lipid-derived RCS triggering the signal cascade in plant cells (Farmer and Mueller, 2013;Biswas and Mano, 2015).…”

“…These facts suggest that chloroplasts are exposed to a high risk of lipid peroxidation. Indeed, Mano et al (2014a) reported that the Arabidopsis (Arabidopsis thaliana) fad7fad8 double mutant contained less lipidderived RCS (acrolein, crotonaldehyde, and malondialdehyde) in its leaves compared with wild-type leaves. Both Arabidopsis FAD7 and FAD8 encode chloroplastic v-3 fatty acid desaturases that convert 16:2 and 18:2 fatty acids into 16:3 and 18:3 fatty acids (Iba et al, 1993;McConn et al, 1994).…”

Lipid Peroxide-Derived Short-Chain Carbonyls Mediate Hydrogen Peroxide-Induced and Salt-Induced Programmed Cell Death in Plants

“…oxylipin carbonyls; Farmer and Mueller, 2013). The chemical species of oxylipin carbonyl formed in the cells differ according to the fatty acids and the type of ROS involved (Grosch, 1987;Mano et al, 2014a).…”

Reactive oxygen species: Reactions and detection from photosynthetic tissues

“…Formaldehyde, acetaldehyde, propionaldehyde, acrolein, malondialdehyde, (E)-2-hexenal, (Z)-3-hexenal, 4-hydroxy-(E)-2-hexenal and other carbonyls are found to be products of degradation of polyunsaturated fatty acids [450], and therefore aldehydes can be used as markers of lipid peroxidation. Measurement of coloured substances produced in a reaction between aldehydes and thiobarbituric acid (TBA) is the most commonly applied method [451].…”

“…Measurement of coloured substances produced in a reaction between aldehydes and thiobarbituric acid (TBA) is the most commonly applied method [451]. A new method for a comprehensive analysis of oxylipin carbonyls (quantitation and structural estimation) in plants with reverse-phase HPLC has recently been established [450,452]. …”