Lipoxygenase pathway in model bryophytes: 12-oxo-9(13),15-phytodienoic acid is a predominant oxylipin in Physcomitrella patens

The model moss Physcomitrella patens and liverwort Marchantia polymorpha possess all enzymatic machinery responsible for the initial stages of jasmonate pathway, including the active 13(S)-lipoxygenase, allene oxide synthase (AOS) and allene oxide cyclase (AOC). At the same time, the jasmonic acid is missing from both P. patens and M. polymorpha. Our GC-MS profiling of oxylipins of P. patens gametophores and M. polymorpha tissues revealed some distinctive peculiarities. The 15(Z)-cis-12-oxo-10,15-phytodienoic acid (12-OPDA) was the major oxylipin in M. polymorpha. In contrast, the 12-OPDA was only a minor constituent in P. patens, while another cyclopentenone 1 was the predominant oxylipin. Product 1 was identified by its MS, 1H-NMR, 1H–1H–COSY, HSQC and HMBC data as 15(Z)-12-oxo-9(13),15-phytodienoic acid, i.e., the iso-12-OPDA. The corresponding C16 homologue, 2,3-dinor-iso-12-OPDA (2), have also been detected as a minor component in P. patens and a prominent product in M. polymorpha. Besides, the 2,3-dinor-cis-12-OPDA (3) was also present in M. polymorpha. Apparently, the malfunction of cyclopentenone reduction by the 12-OPDA reductase in P. patens and (to a lesser extent) in M. polymorpha leads to the isomerization of 12-OPDA and formation of specific cyclopentenones 1 and 2, which are uncommon in flowering plants. [Display omitted] •Oxylipin profiles of Physcomitrella patens and Marchantia polymorpha were studied.•The iso-12-OPDA is a predominant oxylipin in P. patens.•Dinor-iso-12-OPDA is prominent in both P. patens and M. polymorpha.•M. polymorpha possesses 12-OPDA and dinor-12-OPDA.•Unusual cyclopentenone metabolism is related to jasmonate loss in Bryophyta.