Taki et al. used microarray analysis to show that, although some of the genes regulated by jasmonates (JAs) and the jasmonate precursor 12-oxo-phytodienoic acid (OPDA) are the same, OPDA also regulates the expression of a separate subset of genes. Selected genes were further evaluated using a mutant that could not convert OPDA to JA to verify that OPDA regulated their expression. Wounding regulated 50% of the genes affected by either exogenous JA or exogenous ODPA, consistent with JA and OPDA having roles in the wound response. Using two mutants in the biosynthetic pathway of JA--one downstream of OPDA and one upstream of OPDA--the authors provided further support for an OPDA-specific role in wound signaling. Unlike the effects of JAs, OPDA stimulation of gene expression appeared not to require the F-box protein COI1, because Arabidopsis coi1-16 mutants continued to exhibit OPDA-mediated gene transcription but lacked JA-mediated gene transcription. Thus, OPDA appears to activate a pathway that is separate from the JA pathway, which requires COI1.
N. Taki, Y. Sasaki-Sekimoto, T. Obayashi, A. Kikuta, K. Kobayashi, T. Ainai, K. Yagi, N. Sakurai, H. Suzuki, T. Masuda, K.-i. Takamiya, D. Shibata, Y. Kobayashi, H. Ohta, 12-oxo-phytodienoic acid triggers expression of a distinct set of genes and plays a role in wound-induced gene expression in Arabidopsis. Plant Phys. 139, 1268-1283 (2005). [Abstract] [Full Text]