Abstract
Abiotic and biotic stresses typically trigger the formation of an array of enzymatically and non-enzymatically oxidized lipids including α,β-unsaturated aldehydes and ketones. Several members of the later group are chemically reactive and covalently bind to proteins both in vitro and in Arabidopsis thaliana in vivo. We show that cyclopentenone oxylipins (12-oxo-phytodienoic acid and several phytoprostanes) induce a common pattern of genes involved in secondary metabolism and detoxification while genes involved in cell division and growth are down regulated. Gene regulation by reactive cyclopentenones is to a large part independent of COI1 but dependent on TGA transcription factors. Some of the strongly up-regulated detoxification genes such as GST6 and OPR1 detoxify cyclopentenones in vitro but at the same time GST6 becomes itself gradually covalently modified and inactivated. Hence, endogenous reactive oxylipins may be involved in signalling and cell rescue at low levels but may significantly damage proteins at high levels.
