**3. Survey of AMF that colonize maize**

Host specificity of AMF is a longtime debate among researchers. Although many authors argued that AMF have no host-plant specificity [58], several studies tend to demonstrate the preference of some AMF genus to some plant species [59]. Crops like maize have a relatively high mycorrhizal dependency for plant growth and nutrient uptake [60]. Mycorrhizal dependency is an intrinsic property of every plant species that depend on the AMS. The type of crop, the soil properties, and the effect of the cropping system characterize mycorrhizal dependency [61]. There are three categories of plant species according to their mycorrhizal dependency. First, non-mycotrophic plants are capable of developing without the intervention of mycorrhizal fungi. Secondly, facultative mycotrophs require that reproduction occurs in the presence of mycorrhizal symbiosis only when the environment in which they grow is nutrient-limited. Lastly, obligate mycotrophs can only complete their development cycle associated with AMF. To study mycorrhizal dependency, the percentage of root colonized by AMF is a critical index. For example, the root colonization rate is 0% for *Brassica napus* and between 50 and 70% for *Z. mays* [62].


Furthermore, researchers use different methods such as trap cultures, wet sieving, morphological identification of spores, and molecular tools to determine AMF

### **Table 1.**

*Examples of AMF species associated with maize.*

*Climate-Smart Maize Breeding: The Potential of Arbuscular Mycorrhizal Symbiosis… DOI: http://dx.doi.org/10.5772/intechopen.100626*

communities associated with maize. Based on such methods, many authors showed that maize crops could associate with different AMF species belonging to various genera (**Table 1**). *Paraglomeraceae, Aucolosporaceae, Gigasporaceae, Glomeraceae, Archaeosporaceae,* and *Paraglomeraceae* are the AMF families that associated with maize; however, the Glomus group preponderant [63, 64, 66, 68, 69, 71]. Although it is well established that the genus Glomus has the most widespread dispersion, maize genotypes and agricultural systems influence the mycorrhizal community. Evaluation of maize varieties with different genomes revealed colonization levels depend largely and continuously on maize genotypes within each germplasm [70]. Maize monoculture also reduces AMF diversity [68, 71, 72]. For instance, Archaeosporaceae and Paraglomeraceae group are not colonizers of maize grown in monoculture [69].
