Arbuscular mycorrhizal fungi and mycorrhizal symbiosis: Physiological, biochemical and molecular aspects.

This review analyzes the physiological, biochemical and molecular implications related to the interaction between arbuscular mycorrhizal fungi (AMF) and plants in the pre-symbiotic and symbiotic stages.Factors involving spore germination, germ tube growth, signaling and recognition of mycorrhizal fungi are discussed from a macro context, in which the plant interacts with the environment, to a most intrinsic context, in which genes are involved in this interaction.The colonization stages, from the formation of hyphopodium to the differentiation of arbuscules, are described according to cellular changes and molecular mechanisms.The dynamics of nutrient exchanges are discussed bidirectionally, from the fungus to the plant and from the plant to the fungus.The regulation processes of absorption and transport of water, phosphorus, nitrogen and calcium, and carbohydrates via the periarbuscular membrane are described in cellular, functional and molecular terms.The most common changes in the secondary metabolism of plants associated to AMF are also presented, based on biochemical processes.The conjuncture analysis showed that in the last decade, studies made efforts to identify the mechanisms of communication and symbiosis functioning, differently from studies carried in the past decades, which extensively investigated the aspects related to the growth responses of symbionts, especially in plants.