Arbuscular mycorrhizal fungi and plant root exudates bio-communications in the rhizosphere

Abstract

The pre-symbiosis of arbuscular mycorrhizal fungi (AMF) is induced by the production of specific plant root exudates. Mycorrhizal fungi symbiotic relationships have many benefits to the plants. These benefits include, improved plant growth and developments, and enhanced plant tolerance to several diseases. Over the pre-symbiotic phase, the root releases essential metabolites necessary for fungal growth and root colonization. Root exudates compounds were reported and identified by several researchers. Root exudates have sugar, amino acids, proteins, carbon, some lipophilic compounds, flavonoids, and other bio-molecules. These compounds were presented as a critical and fundamental signal in plant, fungal and microbe bio-communications in the soil. Root-microbe interactions are continuous occurrences in the biological active soil zone. Mycorrhizal fungi bio-interaction can be classified as positive (symbiotic) to the host or could be negative to the plant. Root exudates may act as messengers that communicate and initiate biological and physical interactions between soil organisms and roots. The current review will illustrate the role of root exudates in mycorrhizal fungi association, the major components of root exudates and more focus on the disease control by root exudates derived from plants mycorrhizosphere.