rhizoplane

The rhizoplane is the root surface in direct contact with soil and the adherent microbial community that remains attached to the root after gentle washing. It represents the immediate interface through which the plant exchanges signals and nutrients with soil organisms.

It is a component of the broader rhizosphere, the zone of soil influenced by root activities, and is distinct from the endosphere, the interior of root tissues where internal colonization occurs. The rhizoplane hosts a diverse assemblage of microorganisms, typically including bacteria and fungi, and often functions as a selective arena where root exudates and mucilage shape community structure and activity.

Microbial residents of the rhizoplane participate in nutrient cycling, hormone production, and defense-related interactions. They can solubilize phosphorus, fix nitrogen, sequester iron through siderophores, and produce enzymes or antibiotics that influence nutrient availability and pathogen suppression. By competing with pathogens and modulating signaling with the plant, rhizoplane microbes can affect plant growth, health, and stress responses. Their activity is linked to nutrient uptake efficiency and the plant’s overall performance in various environments.

The composition and function of the rhizoplane microbiome are influenced by plant genotype and developmental stage, root architecture and exudate profile, soil type, moisture, pH, and other abiotic factors. In turn, the rhizoplane microbial community helps determine plant resilience and productivity.

Methods to study the rhizoplane often involve washing or sonication to separate loosely attached soil from the root, followed by DNA sequencing, microscopy, or culturing to characterize the adherent microbiota. Definitions of the rhizoplane can be operational, depending on the washing strength used to distinguish tightly bound microbes from the surrounding rhizosphere.