AMF’s Main Structures

Abstract

In this chapter I discuss about the AMF main structures. So, I introduce you the main structures of arbuscular mycorrhizal fungi, like: hyphae, arbuscules, vesicles, and auxiliary cells, as well as, the development of the symbiosis, how does it work, and the main abiotic and biotic factors that can mediate the development of the mycorrhiza. The development of the symbioses begins with the spore germination (Asymbiotic phase) because spore germination does not depend of the host plant. It depends of biotic and abiotic favorable conditions to occur like: moisture, temperature, pH, mineral nutrients level, organic matter, soil microorganisms, and pollutants action. Pre-symbiotic phase starts even before physical contact between symbionts, where both AMF species and host plants start to exchange chemical and molecular signals, and its success is very dependent of soil properties (e.g., pH, moisture and temperature), and the host plant (e.g., root exudates, like flavonoids, CO2, and unknown ramification factors). After to establish physical contact with root surface, extraradical hyphae differentiate in appressorium, and here starts the Symbiotic phase. Once into root, AMF are able to develop extra- and intraradical hyphae, arbuscules, vesicles, auxiliary cells, and spores.