Graduate School of Biostudies, Kyoto University, Kyoto 606-8502,Japan.
Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, 183-8509,Japan.
Plant Cell. 2023 Oct 30;35(11):4111-4132. doi: 10.1093/plcell/koad216.
Gibberellins (GAs) are key phytohormones that regulate growth, development, and environmental responses in angiosperms. From an evolutionary perspective, all major steps of GA biosynthesis are conserved among vascular plants, while GA biosynthesis intermediates such as ent-kaurenoic acid (KA) are also produced by bryophytes. Here, we show that in the liverwort Marchantia polymorpha, KA and GA12 are synthesized by evolutionarily conserved enzymes, which are required for developmental responses to far-red light (FR). Under FR-enriched conditions, mutants of various biosynthesis enzymes consistently exhibited altered thallus growth allometry, delayed initiation of gametogenesis, and abnormal morphology of gamete-bearing structures (gametangiophores). By chemical treatments and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses, we confirmed that these phenotypes were caused by the deficiency of some GA-related compounds derived from KA, but not bioactive GAs from vascular plants. Transcriptome analysis showed that FR enrichment induced the up-regulation of genes related to stress responses and secondary metabolism in M. polymorpha, which was largely dependent on the biosynthesis of GA-related compounds. Due to the lack of canonical GA receptors in bryophytes, we hypothesize that GA-related compounds are commonly synthesized in land plants but were co-opted independently to regulate responses to light quality change in different plant lineages during the past 450 million years of evolution.
赤霉素（GAs）是调节被子植物生长、发育和环境响应的关键植物激素。从进化的角度来看，所有主要的 GA 生物合成步骤在维管植物中都是保守的，而 GA 生物合成中间体，如 ent-贝壳杉烯酸（KA），也存在于苔藓植物中。在这里，我们表明，在苔类植物 Marchantia polymorpha 中，KA 和 GA12 是由进化保守的酶合成的，这些酶是对远红光（FR）发育反应所必需的。在 FR 富集条件下，各种生物合成酶的突变体表现出明显的藻体生长比例改变、配子发生延迟以及配子囊结构（配子囊柄）的异常形态。通过化学处理和液相色谱-串联质谱（LC-MS/MS）分析，我们证实这些表型是由 KA 衍生的某些 GA 相关化合物的缺乏引起的，而不是来自维管植物的生物活性 GA。转录组分析表明，FR 富集诱导了与 M. polymorpha 应激反应和次生代谢相关的基因上调，这在很大程度上依赖于 GA 相关化合物的生物合成。由于苔藓植物中缺乏典型的 GA 受体，我们假设 GA 相关化合物在陆生植物中普遍合成，但在过去 4.5 亿年的进化过程中，在不同的植物谱系中被独立地用来调节对光质变化的反应。
