**4. Action of AM fungi against plant pathogens**

With increasing cost of pesticides and the negative effect of this on human health and the environment as well as pathogen resistance, AM fungi offers potential for more sustainable and environmentally friendlier alternative for sustainable agriculture. These fungi are nevertheless most important habitat of the rhizosphere and their activity has direct influence on disease incidence and severity especially on root diseases [71]. There are several reports of possible use of AM fungi in the biocontrol of plant diseases [72–74]. One communality among all these reported evidence are that, AM interactions with plant pathogens tends to reduce their damage to plants caused by fungi and nematodes; a symbiotic association with these plants enhances resistance or tolerance.

In the interaction between AM fungi and plant parasitic nematodes (PPM), for instance, the PPM are known to be very common agricultural soil inhabitants world over and cause extensive damages to many crop species. By their actions, they can be ectoparasites or endoparasites (semi-endoparasites and migratory endoparasites), sedentary endoparasites and causes about 50–60% yield losses and many often these damages are aggravated when other pathogens capitalize on them to cause severe diseases.

Both the nematodes and AM fungi tend to stablish relationship in the rhizosphere due to their common interest in nutrient provided by the host plant. The interaction between these two would have opposite effect on growth and yield that will tend to favor the host plant [75].

Also, plant pathogenic fungi are one of the common occupants of the soil matrix and causes wide range soil-borne diseases. The soil serves as host to these pathogens and cause severe damages to the roots of susceptible hosts. Soil-borne diseases caused by phytopathogenic fungi are also difficult to control due to their ability to develop over seasoning structures such as chlamydospore, sclerotia, rhizomorph, etc. The presence of AM fungi and their interaction with these plant pathogenic fungi in the rhizosphere gives the advantage to the AM fungi to exert its s opposite effect/influence on the plant pathogenic fungi thereby protecting the plant from their attacks, promoting plant growth and enhancing yield of the plant [76, 77].

Finally, there also reports on several other plant pathogens establishing opposite relationship with the AM fungi such as the bacteria, mycoplasma, plant viruses etc. thereby reducing disease incidence and severity in their interactions with AM fungi [78, 79].
