Mineral and Organic Fertilizers Distinctly Affect Fungal Communities in the Crop Rhizosphere

Mikhail V Semenov,George S Krasnov,Vyacheslav M Semenov,Ariena Van Bruggen

doi:10.3390/jof8030251

Abstract

Fungi represent a diverse group of organisms that play an essential role in maintaining soil health and ecosystem functioning. Plant root exudates form nutrient-rich niches that harbor specific fungal communities, or so-called rhizosphere mycobiomes. The long-term application of fertilizers supplies the soil with nutrients that may override the plant-related effects on rhizosphere fungal communities. Here, we assessed the effect of contrasting fertilization regimes on the composition, diversity, and abundance of bulk soil and rhizosphere mycobiomes of potato, white mustard, and maize under NPK (mineral fertilizers) or fresh cattle manure (organic fertilizers). Mineral and organic fertilizers led to distinct fungal communities in the rhizospheres of all studied crops, and the plant-related effects on the mycobiome were overridden by the effect of fertilization. The abundances of Ascomycota and Olpidiomycota were higher under manure, while the abundances of Basidiomycota and Monoblepharomycota increased under NPK. Manure input strongly increased fungal abundance but decreased fungal diversity and the total number of species. NPK had a slight effect on fungal diversity, but significantly increased the relative abundances of fungal phytopathogens, such as Alternaria and Fusarium. Our study shows that that potential plant species effects on the abundance and diversity of the rhizosphere mycobiomes are governed by long-term fertilization. Fertilization management could therefore be used to manipulate rhizosphere fungal communities and soilborne pathogen suppressiveness.

Highlights

Fungi represent a highly diverse group of organisms that play an essential role in maintaining soil health and ecosystem functioning [1]
Fungi interact with plants at various niches, including the rhizosphere—a narrow zone of soil adjacent to the roots of living plants that is directly influenced by root exudates
We considered the genera Trichoderma, Cladorrhinum, and Humicola, which are known as biocontrol agents against plant pathogens and opportunistic avirulent plant symbionts

Summary

Introduction

Fungi represent a highly diverse group of organisms that play an essential role in maintaining soil health and ecosystem functioning [1]. Fungi are important decomposers and recyclers of recalcitrant or labile organic materials [2]. They are often involved in symbiosis with plant roots [3], they can be soil-borne plant pathogens [4]. Many fungal groups combine these opposite lifestyles—saprophytic, pathogenic, or symbiotic—and they can switch between different strategies depending on the environmental conditions [5]. Despite their high biomass and importance for ecosystem sustainability, the fungal diversity in soil is significantly less studied than the bacterial diversity [4]. The rhizosphere mycobiome includes many potential plant pathogens and their antagonists, and can influence plant health and soil disease suppressiveness [7,8]. Understanding the factors that shape the composition and intermicrobial relationships of the rhizosphere mycobiome is an important step to control plant health and productivity [10,11]

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Conclusion