Rhizosphere fungal communites of resistant banana varieties

Beneficial interactions between plants and rhizosphere microorganisms are key determinants of plant health with potential to enhance the sustainability of agricultural practices. However, pinpointing the mechanisms that determine plant disease protection is difficult due to the complexity of microbial and plant-microbe interactions and links with the plant's own defense systems. We therefore sought to disentangle a number of components related to suppression of Fusarium oxysporum f. sp cubense tropical Race 4 (Foc TR4), including the impact of plant (banana) variety, rhizosphere fungi and the plant metabolome. Using cultivation-independent approaches, we sought to identify fungal taxa associated with disease suppression and further used cultivation-based approaches to examine the potential of such taxa to inhibit the pathogen. We found that different banana varieties were associated with distinctive rhizosphere fungal communities that differed in their ability to inhibit the pathogen. Trichoderma and Penicillium were detected as potential key taxa of resistant banana varieties, and the suppressive activities of these two genera against Foc TR4 were confirmed using pot experiments with inoculation of isolated strains of these taxa. Metabolome analysis showed that resistant banana varieties promoted the proliferation of Trichoderma and Penicillium through specific metabolites, such as shikimic acid, D-ribofuranose and propylene glycol. In summary, our findings suggest that the ability to recruit pathogen-suppressive fungal taxa may be an important component determining the level of pathogen resistance exhibited by plant cultivars. This perspective opens up new avenues for improving plant health in which both plant and associated microbial properties are considered.