Mechanisms of induction of the stress-responsive transcription factors HsfA2 and DREB2A by 12-oxo-phytodienoic acid in Arabidopsis thaliana.

OPDA (12-oxo-phytodienoic acid) not only is an intermediate in jasmonic acid biosynthesis but also regulates gene expression, although mechanisms of OPDA-induced signaling are largely unknown. Here, we measured transcriptional responses of the OPDA-responsive genes HsfA2 and DREB2A to the protein synthesis inhibitor cycloheximide and to the HSP90 inhibitor geldanamycin. The results suggest that HSP90 and other proteins suppress the expression.

Arabidopsis mutants affecting oxylipin signaling in photo-oxidative stress responses.

Plant oxylipins derive from oxygenation of polyunsaturated fatty acids in thylakoid membranes and oxylipins such as jasmonic acid (JA) and 12-oxo-phytodienoic acid (OPDA) play important roles in adaptation to photo-oxidative stress. OPDA functions both as a JA precursor and as a biologically active signaling molecule that induces expression of a specific set of genes. These genes can be induced by OPDA in the JA-insensitive coronatine insensitive1 (coi1) mutant, suggesting that there is an alternative pathway for OPDA signaling, independent of COI1-dependent JA signaling.