Overview

Abstract

In this chapter I introduce what are arbuscular mycorrhizal fungi (AMF). So, I respond four main answers about AMF, their biological characteristics, how AMF colonize the plant roots, and finally I describe their molecular characteristics. Basically, AMF are obligate root symbionts that establish a mutualistic symbiosis with several plants and have key role in increasing plant growth, resistance, and tolerance to abiotic and biotic stresses. They are incapable of independent growth (in nature or axenic culture) without host plants and their main structures are: arbuscules, vesicles, auxiliary cells, hyphae and spores. Root colonization is mediated by genetic, morphological and functional interactions between partners of the symbiosis that begins even before the physical contact between the host-plant and AMF species. For their molecular characteristic we can explain that they have a large variation in their genome (varying greatly between species). For example, Rhizophagus intraradices has a small genome, close to 16.54 Mb (of which 88.36 % are single copy DNA, 1.59 % are repetitive sequences and 10.05 % foldback DNA), while other species, like Scutellospora pellucida and Racocetra gregaria have genomes with much larger size may vary 127.4 Mb in the 1058.4 Mb respectively.