Graduate Program in Genetics and Molecular Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
Brazilian Biorenewables National Laboratory (LNBR), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, Brazil.
Nat Commun. 2024 Sep 12;15(1):7994. doi: 10.1038/s41467-024-52367-6.
Lignin, a major plant cell wall component, has an important role in plant-defense mechanisms against pathogens and is a promising renewable carbon source to produce bio-based chemicals. However, our understanding of microbial metabolism is incomplete regarding certain lignin-related compounds like p-coumaryl and sinapyl alcohols. Here, we reveal peripheral pathways for the catabolism of the three main lignin precursors (p-coumaryl, coniferyl, and sinapyl alcohols) in the plant pathogen Xanthomonas citri. Our study demonstrates all the necessary enzymatic steps for funneling these monolignols into the tricarboxylic acid cycle, concurrently uncovering aryl aldehyde reductases that likely protect the pathogen from aldehydes toxicity. It also shows that lignin-related aromatic compounds activate transcriptional responses related to chemotaxis and flagellar-dependent motility, which might play an important role during plant infection. Together our findings provide foundational knowledge to support biotechnological advances for both plant diseases treatments and conversion of lignin-derived compounds into bio-based chemicals.
木质素是植物细胞壁的主要成分之一，在植物防御机制中对抗病原体方面起着重要作用，并且是一种有前途的可再生碳源，可以用于生产基于生物的化学品。然而，我们对某些与木质素有关的化合物（如对香豆醇和松柏醇）的微生物代谢的理解还不完全。在这里，我们揭示了植物病原体柑橘黄单胞菌中三种主要木质素前体（对香豆醇、松柏醇和松柏醇）的分解代谢的周边途径。我们的研究表明，这些单酚类物质进入三羧酸循环所需的所有酶促步骤，同时揭示了芳基醛还原酶，这些酶可能保护病原体免受醛类毒性的影响。它还表明，与木质素有关的芳香族化合物激活与趋化性和鞭毛依赖运动相关的转录反应，这在植物感染过程中可能起着重要作用。总之，我们的研究结果为支持生物技术的进步提供了基础，既可用于植物疾病的治疗，也可用于将木质素衍生化合物转化为基于生物的化学品。
