Hladík Pavel, Brunoni Federica, Žukauskaitė Asta, Zatloukal Marek, Bělíček Jakub, Kopečný David, Briozzo Pierre, Ferchaud Nathan, Novák Ondřej, Pěnčík Aleš
Laboratory of Growth Regulators, Institute of Experimental Botany, The Czech Academy of Sciences & Faculty of Science, Palacký University, Olomouc, Czech Republic.
Department of Chemical Biology, Faculty of Science, Palacký University, Olomouc, Czech Republic.
J Exp Bot. 2025 Mar 24. doi: 10.1093/jxb/eraf092.
In recent years, substantial progress has been made in exploring auxin conjugation and metabolism, primarily aiming at indole-3-acetic acid (IAA). However, the metabolic regulation of another key auxin, phenylacetic acid (PAA), remains largely uncharacterized. Here, we provide a comprehensive exploration of PAA metabolism in land plants. Through LC-MS screening across multiple plant species and their organs, we identified four previously unreported endogenous PAA metabolites: phenylacetyl-leucine (PAA-Leu), phenylacetyl-phenylalanine (PAA-Phe), phenylacetyl-valine (PAA-Val), and phenylacetyl-glucose (PAA-glc). Enzyme assays, genetic evidence, crystal structures, and docking studies demonstrate that PAA and IAA share core metabolic machinery, revealing a complex regulatory network that maintains auxin homeostasis. Furthermore, our study of PAA conjugation with amino acids and glucose suggests limited compensatory mechanisms within known conjugation pathways, pointing to the existence of alternative metabolic routes in land plants. These insights advance our knowledge of auxin-specific metabolic networks and highlight the unique complexity within plant hormone regulation.
近年来，在探索生长素缀合和代谢方面取得了重大进展，主要针对吲哚 - 3 - 乙酸（IAA）。然而，另一种关键生长素苯乙酸（PAA）的代谢调控在很大程度上仍未得到充分研究。在此，我们对陆地植物中的PAA代谢进行了全面探索。通过对多种植物物种及其器官进行液相色谱 - 质谱筛选，我们鉴定出四种先前未报道的内源性PAA代谢物：苯乙酰 - 亮氨酸（PAA - Leu）、苯乙酰 - 苯丙氨酸（PAA - Phe）、苯乙酰 - 缬氨酸（PAA - Val）和苯乙酰 - 葡萄糖（PAA - glc）。酶活性测定、遗传学证据、晶体结构和对接研究表明，PAA和IAA共享核心代谢机制，揭示了一个维持生长素稳态的复杂调控网络。此外，我们对PAA与氨基酸和葡萄糖缀合的研究表明，已知缀合途径中的补偿机制有限，这表明陆地植物中存在替代代谢途径。这些见解推进了我们对生长素特异性代谢网络的认识，并突出了植物激素调控中独特的复杂性。
