L-arabinose: a strategic modulator of pathogen virulence for food system safety.

L-arabinose is a natural pentose sugar widely present in plant cell walls and agricultural residues. It functions both as a carbon source and a signaling molecule, endowing it with significant potential for applications. This article reviews the sources, microbial metabolism, and signal transduction pathways of L-arabinose, with a focus on its regulatory roles and mechanisms in the gut ecosystem and the plant rhizosphere microenvironment. In the gut, L-arabinose modulates microbiota composition, repairs the intestinal barrier, maintains water and salt balance, and influences gastrointestinal hormones and neurotransmitters, thereby inhibiting foodborne pathogens and alleviating constipation. In the plant rhizosphere, L-arabinose activates defense pathways, enhances crop resistance against pathogens, and improves the disease-suppression ability of biocontrol agents. This review aims to provide a theoretical foundation for developing L-arabinose-based functional food ingredients and sustainable crop protection strategies, offering innovative approaches to improve the safety and resilience of food systems.