The plant holobiont: integrating molecular priming and ecological legacies for climate-adaptive immunity.

Plants serve as central hubs of complex network connecting above- and below-ground inhabitants. These relationships are further shaped by abiotic factors that impact the performance of all organisms in direct or indirect contact. Plant immunity orchestrates the outcomes of these interactions through multiple layers of perception, signal integration, and chemical responses. Although biotic and abiotic dynamics are highly visible in the phyllosphere, the soil represents a vast interface of constant interaction, including the effects of abiotic stressors. As a core component of plant immunity, contact with soil organisms contributes to the complex architecture of plant defense, leveraging the second functional genome to bolster an extended plant immune response. Consequently, continuous contact with organisms will serve as a priming stimulus, fostering systemic resilience against future challenges, particularly in a landscape where environmental fluctuations directly modulate pathogen virulence and soil health. In light of recent literature, the present review calls for the integration of ecological contexts into molecular studies of plant immunity, bridging the gap between cellular mechanisms and ecological dynamics to address the challenges of climate uncertainty.