Allyl isothiocyanate depletes glutathione and upregulates expression of glutathione S-transferases in Arabidopsis thaliana

Abstract

Allyl isothiocyanate (AITC) is a phytochemical associated with plant defense in plants from the Brassicaceae family. AITC has long been recognized as a countermeasure against external threats, but recent reports suggest that AITC is also involved in the onset of defense-related mechanisms such as the regulation of stomatal aperture. However, the underlying cellular modes of action in plants remain scarcely investigated. Here we report evidence of an AITC-induced depletion of glutathione (GSH) and the effect on gene expression of the detoxification enzyme family glutathione S-transferases (GSTs) in Arabidopsis thaliana. Treatment of A. thaliana wild-type with AITC resulted in a time- and dose-dependent depletion of cellular GSH. AITC-exposure of mutant lines vtc1 and pad2-1 with elevated and reduced GSH-levels, displayed enhanced and decreased AITC-tolerance, respectively. AITC-exposure also led to increased ROS-levels in the roots and loss of chlorophyll which are symptoms of oxidative stress. Following exposure to AITC, we found that GSH rapidly recovered to the same level as in the control plant, suggesting an effective route for replenishment of GSH or a rapid detoxification of AITC. Transcriptional analysis of genes encoding GSTs showed an upregulation in response to AITC. These findings demonstrate cellular effects by AITC involving a reversible depletion of the GSH-pool, induced oxidative stress, and elevated expression of GST-encoding genes.

Brassica meal‐derived allyl‐isothiocyanate postharvest application: influence on strawberry nutraceutical and biochemical parameters

“…Although the interaction of AITC with GSSG was demonstrated in in vitro experiments, the GSH reversible depletion and consequent ROS accumulation has been previously observed in AITC treated A. thaliana seedlings . This action previously suggested a role of the glutathione system in the detoxification/control of isothiocyanates in plant tissue, in accordance with findings in insects and mammalian cells . Nonetheless, despite the different system and model plant considered in the other studies, the concentration used in the present study was much lower than that used for other in vitro/in vivo investigations and this might have played a critical role in expressing its pro‐ or anti‐oxidant action and biological effects .…”

“…Such a multifunctional role is also supported by a genome scale transcriptional profiling of A. thaliana exposed to AITC, which shows the induction of a rapid response involving numerous processes considered to be part of a plant defence strategy . In addition, AITC has been seen to induce, in Arabidopsis , cellular reversible glutathione depletion and up‐regulation of genes that encode glutathione S ‐transferase, which have been suggested as the plant isothiocyanate detoxification/control mechanism . At the same time, in small berry fruit, AITC has shown not only to reduce decay, but also to exert a pro‐oxidant action detected by an increased ROS production which, again, has been suggested as a possible plant defence mechanism induced by AITC …”

Cruciferous Vegetables, Isothiocyanates, and Bladder Cancer Prevention

“…A study by Overby et al showed that isothiocyanates disrupted microtubules in Arabodopsis thalinia and in AY-27 rat bladder cancer cells suggesting that plant and mammalian cells share isothiocyante-mediated antigrowth mechanisms. [142] Additionally, SFN was also shown to induce mitotic arrest, however, not in the G2 phase of the cell cycle. Park et al revealed that 5637 human bladder cancer cells treated with SFN underwent caspase-dependent apoptosis via accumulation of ROS.…”

Glutathione protects Candida albicans against horseradish volatile oil

“…This observation suggests that GSH depletion is not necessary for the antifungal activity of HREO. The induction of GST (Table ), an enzyme which catalyses the reaction between GSH and ITCs , at low‐HREO concentration, as well as the depletion of GSH pools at high concentration, suggest that HREO reacted with GSH in vivo but cells could counterbalance this process at low‐HREO levels. Not surprisingly CDNB, a well known chemical which decreases the GSH pool in C. albicans , showed strong synergism with HREO (Table ).…”

“…It induces oxidative stress most likely due to its effect on mitochondrial functions . Cells can detoxify HREO components by GSH . GSH reacts spontaneously with ITCs, and GST may also catalyze this reaction.…”