Wounding stimulates the accumulation of glycerolipids containing oxophytodienoic acid and dinor-oxophytodienoic acid in Arabidopsis leaves.
Although oxylipins can be synthesized from free fatty acids, recent evidence suggests that oxylipins are components of plastid-localized polar complex lipids in Arabidopsis (Arabidopsis thaliana). Using a combination of electrospray ionization (ESI) collisionally induced dissociation time-of-flight mass spectrometry (MS) to identify acyl chains, ESI triple-quadrupole (Q) MS in the precursor mode to identify the nominal masses of complex polar lipids containing each acyl chain, and ESI Q-time-of-flight MS to confirm the identifications of the complex polar lipid species, 17 species of oxylipin-containing phosphatidylglycerols, monogalactosyldiacylglycerols (MGDG), and digalactosyldiacylglycerols (DGDG) were identified. The oxylipins of these polar complex lipid species include oxophytodienoic acid (OPDA), dinor-OPDA (dnOPDA), 18-carbon ketol acids, and 16-carbon ketol acids. Using ESI triple-Q MS in the precursor mode, the accumulation of five OPDA- and/or dnOPDA-containing MGDG and two OPDA-containing DGDG species were monitored as a function of time in mechanically wounded leaves. In unwounded leaves, the levels of these oxylipin-containing complex lipid species were low, between 0.001 and 0.023 nmol/mg dry weight. However, within the first 15 min after wounding, the levels of OPDA-dnOPDA MGDG, OPDA-OPDA MGDG, and OPDA-OPDA DGDG, each containing two oxylipin chains, increased 200- to 1,000-fold. In contrast, levels of OPDA-hexadecatrienoic acid MGDG, linolenic acid (18:3)-dnOPDA MGDG, OPDA-18:3 MGDG, and OPDA-18:3 DGDG, each containing a single oxylipin chain, rose 2- to 9-fold. The rapid accumulation of high levels of galactolipid species containing OPDA-OPDA and OPDA-dnOPDA in wounded leaves is consistent with these lipids being the primary products of plastidic oxylipin biosynthesis.
Buseman
Christen M
CM
Division of Biology, Kansas State University, Manhattan, 66506, USA.
Tamura
Pamela
P
Sparks
Alexis A
AA
Baughman
Ethan J
EJ
Maatta
Sara
S
Zhao
Jian
J
Roth
Mary R
MR
Esch
Steven Wynn
SW
Shah
Jyoti
J
Williams
Todd D
TD
Welti
Ruth
R
D017360:Arabidopsis / Q000737:chemistry / Q000378:metabolism*; D002736:Chloroplasts / Q000737:chemistry / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D038983:Galactolipids / Q000378:metabolism; D007659:Ketones / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism*; D010935:Plant Diseases; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
D004075:Diglycerides; D005231:Fatty Acids, Unsaturated; D038983:Galactolipids; D007659:Ketones; D010715:Phosphatidylglycerols; C025999:12-oxophytodienoic acid