crosskingdom

Crosskingdom is a term used to describe interactions, signals, or processes that span more than one biological kingdom, most often involving plants, fungi, bacteria, and animals. In biology it denotes communication and functional effects that cross taxonomic boundaries and is applied to both ecological relationships and molecular mechanisms.

Key areas include cross-kingdom signaling, where molecules produced by one kingdom influence physiology in another; cross-kingdom RNA exchange, in which small RNAs move between organisms; and cross-kingdom gene transfer, including horizontal transfer events that cross kingdom lines, though relatively rare. Mechanisms include chemical signaling, metabolites, extracellular vesicles, and the movement of small RNAs.

Examples are found in plant–microbe interactions such as mycorrhizal signaling, bacterial or fungal effectors that modulate plant immunity, and plant exudates shaping microbial communities; animal–microbe interactions in the gut and skin also involve cross-kingdom communication.

Research methods combine genomics, transcriptomics, metabolomics, and proteomics across interacting organisms; experimental approaches include co-culture systems, receptor–ligand assays, and imaging of signaling processes.

Applications and significance include improving crop resilience through enhanced biocontrol and biofertilizers, guiding breeding for resistance, and deepening understanding of ecosystem networks and host–microbiome relationships. Crosskingdom research highlights how interconnected life is across biological boundaries and informs both basic biology and applied sciences.