Ligand diversity guarantees full activation of the jasmonate pathway in Marchantia polymorpha (array). Ligand diversity guarantees full activation of the jasmonate pathway in Marchantia polymorpha (array)

In plants, jasmonate signalling regulates a wide range of processes from growth and develop-ment to defence responses and thermotolerance. Bioactive jasmonates, such as JA, JA-Ile, OPDA and dn-OPDA, are derived from C18- and C16- fatty acids (FAs), which are found ubiquitously in the plant kingdom. Bryophytes also contain long chain C20- and C22- FAs (LCFAs), which are absent in most vascular plants but are found in organisms of other king-doms, including mammals. The existence of bioactive jasmonates derived from LCFAs is cur-rently unknown. Here, we describe the identification of an OPDA-like molecule derived from a C20-FA in Marchantia polymorpha, which we term C20-OPDA. This molecule accumulates upon wounding, and when applied exogenously can activate known COI1-dependent and -independent jasmonate responses. Furthermore, we identify a dn-OPDA-like molecule (Δ4-dn-OPDA) deriving from C20-OPDA and demonstrate it to be a ligand of the jasmonate co-receptor (MpCOI1-MpJAZ) in Marchantia. By analysing mutants involved in the production of LCFAs, we elucidate the major biosynthetic pathway of C20-OPDA and Δ4-dn-OPDA. Moreover, using a double mutant compromised in the production of both Δ4-dn-OPDA and dn-OPDA, we demonstrate the additive nature of these molecules in the activation of jasmonate responses. Taken together, our data identify LCFAs as a source of bioactive jasmonates that are essential to plant plasticity and resilience. Overall design: 4 replicates for mock and wound-treated samples