Wound induced TAG biosynthesis is JA-Ile and ABA independent.

Triacylglycerol (TAG) plays a significant role during plant stress - it maintains lipid homeostasis. Upon wounding plants start to accumulate TAG, most likely as a storage of fatty acids (FA) originated from damaged membranes. The major goal of this study was to analyze if this process is depended on the two phytohormones jasmonoyl-isoleucine (JA-Ile) and abscisic acid (ABA) which are involved in wound-signaling. To analyze the regulation of wound-induced TAG accumulation we used mutants deficient in JA-Ile, reduced in ABA and the myb96 mutant which is deficient in an ABA-dependent transcription factor. The expression of genes involved in TAG biosynthesis, and the TAG content after wounding analyzed via LC-MS and GC-FID, as well as plastidial lipid content in all mentioned mutant lines were determined. Moreover, the localization of newly synthesized TAG was investigated by lipid droplet staining. TAG accumulation upon wounding was confirmed in our studies as well as the fact that the newly synthesized TAG is mostly composed of polyunsaturated fatty acids. Nevertheless, all tested mutant lines were able to accumulate TAG in similar to WT manner. We observed differences in reduction of plastidial lipids - in WT plants this reduction was higher than in the mutant lines. Newly synthesized TAG was stored in lipid droplets present at and around the wounded area. Our results showed that TAG accumulation upon wounding is not dependent on JA-Ile nor on ABA. The newly synthesized TAG is composed of unsaturated fatty acids, which have membrane origin, and most likely serves as a transient energy storage.