mycorrhizasignalen

Mycorrhizasignalen (mycorrhizal signals) are the chemical signals exchanged between plant roots and mycorrhizal fungi that underpin the establishment and function of mycorrhizal associations. These signals coordinate recognition, compatibility, and the developmental steps leading to symbiosis. In arbuscular mycorrhizal and ectomycorrhizal systems, signaling is bidirectional: the plant releases signals that stimulate fungal competence, and fungal signals that trigger plant molecular responses.

Plant-to-fungi signals: The most studied class are root exudates called strigolactones, a diverse group of carotenoid-derived diterpenoids. Strigolactones stimulate spore germination and hyphal branching in many AMF and can influence fungal community composition. Other root-derived signals may include amino acids and sugars that serve as cues or nutrients for fungi.

Fungi-to-plant signals: Fungi release lipochitooligosaccharides (LCOs) and short-chain chitooligosaccharides, termed Myc factors. These molecules are perceived by plant LysM receptor-like kinases, triggering intracellular signaling cascades that activate the common symbiosis signaling pathway (CSSP). The CSSP involves calcium oscillations, activation of calcium/calmodulin-dependent kinases (CCaMK), and downstream transcription factors such as CYCLOPS/IPD3, leading to gene expression changes necessary for root colonization and arbuscule development in the cortex or Hartig net formation in the outer root tissues.

Through these signals, plants and fungi coordinate nutrient exchange, with arbuscules delivering phosphorus and other nutrients to the plant in exchange for carbon, and fungi receiving carbohydrates. Mycorrhizal signaling also modulates plant defense responses and root morphology, affecting symbiosis efficiency and plant performance under stress.

Research on mycorrhizasignalen contributes to understanding of plant nutrition, soil ecology, and sustainable agriculture by revealing targets to enhance symbiotic efficiency and reduce fertilizer inputs.