New findings on OPDA: No signaling effect in the early wound response
The plant stress hormone jasmonic acid (JA) and its bioactive form jasmonoyl isoleucine (JA-Ile) play a central role in the plant's defense scenario, especially in cases of wounding due to crushing or feeding damage. JA-Ile accumulates within minutes at the wounding site and, as a signaling molecule, induces the activation of defense genes. The precursor of JA-Ile, the compound OPDA (12-cis-oxo-phytodienoic acid), was also previously considered an important player in wound defense. It was attributed a signaling effect that supposedly manifested in OPDA-dependent activation of various defense genes. This thesis has now been refuted by IPB scientists and partners at the University of Göttingen. In their study in Nature Communications, the plant researchers demonstrate that OPDA has no signaling effect in the early wound response in Arabidopsis. According to their findings, endogenous OPDA does not induce a clear transcriptional signature in either wounded or control plants, and the previously identified OPDA-responsive genes are activated independently of OPDA solely by the wounding.
A genuine transcriptional signature of OPDA has so far only been observed in experiments in which the compound was applied exogenously and in high doses to the plants. This exogenous supply of OPDA led to a clear response in the form of multiple activated defense genes, including in particular the genes involved in sulfur assimilation and glutathione production. In addition, OPDA was shown to disrupt redox homeostasis and inhibit photosynthesis in this scenario. According to the scientists, this transcriptional response to exogenous OPDA could be a general detoxification response, since OPDA, as an electrophilic compound, generally subjects the plant to oxidative stress. A parallel article published by Japanese colleagues even shows that OPDA itself is rapidly converted and that the downstream metabolites of cis-OPDA could function as endogenous chemical signals in A. thaliana. These metabolites are also electrophilic compounds and induce the expression of general stress-responsive genes only at high concentrations.
The apparent toxic effect of high doses of OPDA led scientists to suspect that the JA precursor only accumulates in closed cell compartments. They were able to confirm this hypothesis. Accordingly, OPDA accumulates only in those compartments where it is synthesized, transported, and converted—namely, in the plastids, the cytosol, and the peroxisomes. These results reinforce the assumption that OPDA has no signaling function in the early wound response of Arabidopsis plants.
Original Publication:
Khansa Mekkaoui, Ranjit Baral, Fiona Smith, Moritz Klein, Ivo Feussner & Bettina Hause. Transcriptomics and trans-organellar complementation reveal limited signaling of 12-cis-oxo-phytodienoic acid during early wound response in Arabidopsis. Nature Communications 2025 ,
doi: 10.1038/s41467-025-61832-9.