Arbuscular mycorrhizae (AM) are mutualistic symbiotic associations between fungi of the phylum Glomeromycota and most terrestrial plants. The formation and functioning of AM depend on a complex signal exchange process, which ultimately results in shifts in the metabolism of the symbionts and differentiation of a symbiotic interface in cortical root cells. The mechanisms regulating AM development are not well understood, but it is known that phosphate (P) concentration in plants plays a key role in this process. Plant P concentration may affect the balance of sugars and phytohormones (PH), as well as the expression of plant defense-related genes. With the advent of genomics and proteomics, several genes essential for the development of AM have been identified and their regulation mechanisms are being elucidated. Hitherto, it is known that plants secrete several compounds that stimulate spore germination and the growth of arbuscular mycorrhizal fungi (AMF). There is also evidence that AMF synthesize molecules that are recognized by the host plants. At least three genes are essential for the recognition of this molecule and the transduction of the molecular signal. The roles of these genes and the possible mechanisms regulating their expression, as well as the role of PH in controlling AM development are discussed in this review.
arbuscular mycorrhiza; signaling; phytohormones; defense genes; phosphate