Abstract
Biosolid application is an effective strategy, alternative to synthetic chemicals, for enhancing plant growth and performance and improving soil properties. In previous research, biosolid application has shown promising results with respect to tomato resistance against Fusarium oxysporum f. sp. radicis-lycopersici (Forl). Herein, we aimed at elucidating the effect of biosolid application on the plant–microbiome response mechanisms for tomato resistance against Forl at a molecular level. More specifically, plant–microbiome interactions in the presence of biosolid application and the biocontrol mechanism against Forl in tomato were investigated. We examined whether biosolids application in vitro could act as an inhibitor of growth and sporulation of Forl. The effect of biosolid application on the biocontrol of Forl was investigated based on the enhanced plant resistance, measured as expression of pathogen-response genes, and pathogen suppression in the context of soil microbiome diversity, abundance, and predicted functions. The expression of the pathogen-response genes was variably induced in tomato plants in different time points between 12 and 72 h post inoculation in the biosolid-enriched treatments, in the presence or absence of pathogens, indicating activation of defense responses in the plant. This further suggests that biosolid application resulted in a successful priming of tomato plants inducing resistance mechanisms against Forl. Our results have also demonstrated that biosolid application alters microbial diversity and the predicted soil functioning, along with the relative abundance of specific phyla and classes, as a proxy for disease suppression. Overall, the use of biosolid as a sustainable soil amendment had positive effects not only on plant health and protection, but also on growth of non-pathogenic antagonistic microorganisms against Forl in the tomato rhizosphere and thus, on plant–soil microbiome interactions, toward biocontrol of Forl.
Highlights
The fungus Fusarium oxysporum f.sp. radicis-lycopersici (Forl) is a destructive pathogen limiting crop productivity and causing significant losses in commercial tomato production worldwide [1,2]
Forlincreased increasedin inthe thedifferent different mixtures mixtures of of biosolid biosolid leachates leachates with compared to the control. This increase was greater with PDA compared to the control (Figure 1A)
The effect of biosolid application on the biocontrol of Forl was investigated based on the enhanced plant resistance measured as expression of pathogenresponse genes and the pathogen suppression in the context of soil microbiome diversity, abundance, and predicted functions
Summary
The fungus Fusarium oxysporum f.sp. radicis-lycopersici (Forl) is a destructive pathogen limiting crop productivity and causing significant losses in commercial tomato production worldwide [1,2]. Radicis-lycopersici (Forl) is a destructive pathogen limiting crop productivity and causing significant losses in commercial tomato production worldwide [1,2]. Forl is a saprotrophic soilborne pathogen causing tomato foot and root rot disease (TFFR) [2] by intense colonization of the root hair zone and especially the crown of the plant [1]. Due to the resistant nature of all formae speciales of F. oxysporum, this fungus is extremely difficult to control with synthetic fungicides [2]. Several methods have been used to limit the spread of Forl in field, and greenhouse conditions, such as the use of resistant tomato hybrids and rootstocks, as well as soil disinfection [5], which is a rather expensive practice as it must be repeatedly applied, leading in turn to the increase in hazardous inputs in agriculture
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