Mycorrhiza consortia suppress the fusarium root rot (Fusarium solani f. sp. Phaseoli) in common bean (Phaseolus vulgaris L.)

Abstract

The ability of Arbuscular Mycorrhizal Fungi (AMF) to alleviate the lethal effects incited by root pathogens in a range of plant hosts has been demonstrated. Accumulated evidence also shows that multiple rather than single AMF species exhibit greater potential against pathogens and could mimic natural systems. Nevertheless, it is well established that the effectiveness of a consortium of beneficial organisms is function of interaction among the partners and the involved host. In the present study, four AMF formulations made up of three strains each (1:1:1 w/w) from propagated units of selected AMF strains, Glomus intraradices, Glomus hoi, Gigaspora margarita, and Scutellospora gigantea were evaluated in enhancing common bean (Phaseolus vulgaris L.) growth and biocontrol vis-à-vis Fusariumsolani under greenhouse conditions. The results revealed that all the mycorrhizal preparations significantly reduced the levels of disease severity and incidence in infected bean plants. The biocontrol efficiency of AMF was a function of genera diversity. Though, either neutral or significantly increased growth parameters were recorded upon mycorrhizal colonization. The rhyzospheric competence (root colonization and spore density) of the mycorrhizal formulations was negatively affected upon Fusarium solani inoculation. Moreover, the total soluble phenols and flavonoids contents as well as the specific activity of Phenylalanine Ammonia Lyase (PAL) were boosted after mycorrhizal colonization, indicating the strengthening of plant immune system against the pathogen. Further studies should confirm our formulations after open field assays as alternatives to agrochemicals.