Nonenzymatic oxidation of trienoic fatty acids contributes to reactive oxygen species management in Arabidopsis.
In higher plants such as Arabidopsis thaliana, omega-3 trienoic fatty acids (TFAs), represented mainly by alpha-linolenic acid, serve as precursors of jasmonic acid (JA), a potent lipid signal molecule essential for defense. The JA-independent roles of TFAs were investigated by comparing the TFA- and JA-deficient fatty acid desaturase triple mutant (fad3-2 fad7-2 fad8 (fad3 fad7 fad8)) with the aos (allene oxide synthase) mutant that contains TFAs but is JA-deficient. When challenged with the fungus Botrytis, resistance of the fad3 fad7 fad8 mutant was reduced when compared with the aos mutant, suggesting that TFAs play a role in cell survival independently of being the precursors of JA. An independent genetic approach using the lesion mimic mutant accelerated cell death2 (acd2-2) confirmed the importance of TFAs in containing lesion spread, which was increased in the lines in which the fad3 fad7 fad8 and acd2-2 mutations were combined when compared with the aos acd2-2 lines. Malondialdehyde, found to result from oxidative TFA fragmentation during lesion formation, was measured by gas chromatography-mass spectrometry. Its levels correlated with the survival of the tissue. Furthermore, plants lacking TFAs overproduced salicylic acid (SA), hydrogen peroxide, and transcripts encoding several SA-regulated and SA biosynthetic proteins. The data suggest a physiological role for TFAs as sinks for reactive oxygen species.
Mène-Saffrané
Laurent
L
Plant Molecular Biology Department, University of Lausanne, Biophore, 1015 Lausanne, Switzerland.
Dubugnon
Lucie
L
Chételat
Aurore
A
Stolz
Stéphanie
S
Gouhier-Darimont
Caroline
C
Farmer
Edward E
EE
D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001203:Ascomycota; D003517:Cyclopentanes / Q000378:metabolism*; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D009154:Mutation; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000235:genetics / Q000378:metabolism*
D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D054883:Oxylipins; D017382:Reactive Oxygen Species; D017962:alpha-Linolenic Acid; D008315:Malondialdehyde; C011006:jasmonic acid; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D044943:Fatty Acid Desaturases; C408689:ACD2 protein, Arabidopsis; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase; D020156:Salicylic Acid