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. 4 replicates for mock and wound-treated samples

在植物中，茉莉酸信号通路（jasmonate signalling）调控从生长发育到防御响应及耐热性在内的多种生物学过程。具有生物活性的茉莉酸类化合物，如茉莉酸（JA）、茉莉酸-异亮氨酸结合物（JA-Ile）、12-氧-植物二烯酸（OPDA）与去甲二氢茉莉酸类衍生物（dn-OPDA），均源自广泛分布于植物界的C18和C16脂肪酸（FAs）。苔类植物同样含有长链C20及C22脂肪酸（LCFAs），这类脂肪酸在多数维管植物中缺失，但存在于包括哺乳动物在内的其他生物界类群中。目前，源自长链脂肪酸的生物活性茉莉酸类化合物是否存在仍未可知。本研究在地钱（Marchantia polymorpha）中鉴定出一种源自C20脂肪酸的类OPDA分子，我们将其命名为C20-OPDA。该分子可在创伤胁迫后积累，外源施加时能够激活已知的依赖于COI1与不依赖于COI1的茉莉酸响应途径。此外，我们还鉴定出一种源自C20-OPDA的类dn-OPDA分子（Δ4-dn-OPDA），并证实其为地钱中茉莉酸共受体复合体（jasmonate co-receptor，MpCOI1-MpJAZ）的配体。通过分析长链脂肪酸合成相关突变体，我们阐明了C20-OPDA与Δ4-dn-OPDA的主要生物合成通路。进一步利用同时缺陷Δ4-dn-OPDA与dn-OPDA合成的双突变体，我们证实这两类分子在激活茉莉酸响应过程中具有协同增效效应。综上，本研究的数据表明长链脂肪酸是一类可调控植物可塑性与抗逆性的生物活性茉莉酸类化合物的来源。本研究设置了空白对照（mock）与创伤处理两组样本，每组均包含4次生物学重复。