Changes of microbiome in response to sugars in a wilt pathogen-infested soil

Sugars are frequently and abundantly found in root exudates, but influence of specific sugars on the fate of soil-borne pathogens, microbiome structure, and particularly microbial interactions are not well understood. A 42-day of microcosm incubation was conducted with two soils: a natural watermelon Fusarium wilt pathogen (i.e., Fusarium oxysporum f. sp. niveum (FON))-infested soil (Low-FON soil) and the soil further receiving the wilt pathogen inocula (High-FON soil). Both soils were supplemented with four simple sugars before incubation. The results show that, in both soils, FON was enriched by all sugars although co-living with tremendously diverse microbes; and bacterial richness, evenness, and diversity were decreased and bacterial community structure was changed by all sugars. Bacterial richness and evenness were negatively correlated with FON quantity in both Low-FON and High-FON soils, indicating that FON may tend to live in soil with low alpha-diversity. In both Low-FON and High-FON soils, the sugar-spiked networks had more links, higher density, larger modules, and shorter harmonic geodesic distance, suggesting greater potentials for microbial interaction and niche-sharing. The positive links between some of the keystone taxa and FON indicates that these keystone taxa may have promoted FON. This may be one of reasons why FON could proliferate vigorously after sugar supplementation.