Abstract

Jasmonates are lipid-derived phytohormones that regulate plant development and defense across the green lineage. Thus, understanding the intricacies of jasmonate biosynthesis and signaling is of paramount importance to improve crop yields and food safety. For the last 40 years, the canonical jasmonate biosynthetic pathway has been thoroughly dissected in angiosperms; however, only recent efforts have started to decode the alternative jasmonate biosynthetic networks that operate in bryophytes. In the nonvascular model Marchantia polymorpha, a cis-to-iso isomerization constitutes a key step in the formation of dn-iso-OPDA and Δ4-dn-iso-OPDA, the bioactive jasmonates recognized by a conserved COI1/JAZ co-receptor complex. Their biosynthesis depends on a uniquely expanded fatty acid repertoire that includes, alongside the canonical C16 and C18 omega-3 polyunsaturated fatty acids (PUFAs) found in angiosperms, substantial pools of eicosanoids such as arachidonic acid and eicosapentaenoic acid, essentially absent from flowering plants. Here we trace the jasmonate biosynthetic pathway in bryophytes step-by-step, from PUFA precursors production through lipoxygenase oxygenation and downstream reactions to the processing and catabolic modifications of bioactive compounds. By integrating current knowledge across bryophyte lineages, we identify mechanistic parallels and divergences relative to angiosperms, highlight key unresolved questions, and propose future directions for the field. Deciphering jasmonate biosynthesis in bryophytes is essential for reconstructing the evolutionary origins of jasmonate signaling and understanding how this pathway contributed to the successful colonization of land by plants.

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