Pathogenesis versus symbiosis: a dual perspective on plant-microbe interactions

Plants function as integral components of soil ecosystems, embedded within diverse microbial consortia that engage in continuous chemical and informational exchange. This molecular dialog governs how plants distinguish harmful, neutral, and beneficial microbes, transforming the rhizosphere into a dynamic signaling interface. Microbial interactions operate along a chemical continuum in which metabolites, volatiles, peptides, and other small molecules act across aqueous, lipidic, and chemically heterogeneous microenvironments to shape recognition and response. The physicochemical organization of rhizosphere metabolites may influence their diffusion, stability, and accessibility, although direct evidence for these effects remains limited. Within this framework, plant recognition is reinterpreted as a fluid, context-dependent communication process rather than a binary separation of immunity and symbiosis. This review synthesizes recent advances in the molecular architecture of this continuum, from receptor-mediated signaling to metabolite-driven ecological filtering, and examines how these overlapping systems determine host specificity, community stability, and adaptive resilience. Special attention is given to the regulatory roles of reactive oxygen species (ROS), phytohormones, and redox metabolites as both stress indicators and inter-organismal communicators. By integrating biochemical, ecological, and systems perspectives, this review highlights implications for developing microbiome-based, climate-smart, and sustainable agricultural practices.