Responses of Soil Microbial Communities to the Invasion of Fusarium Oxysporum and Screening for Fusarium Antagonistic Microorganisms From Pathogenic Soil

Abstract

BackgroundFusarium oxysporum is known as a biological pollutant in the farmland soil, that causes vascular wilt on a wide range of cash crops, which is the most destructive disease of plant worldwide. F. oxysporum is a fungus that can colonize and grow saprophytically in plant debris and increase pathogen viability in soil. It is almost impossible to remove once successful colonization. How to effectively reduce the pathogen population and restore the beneficial microbial community in soil is an important subject to control the Fusarium wilt. The main objective of this study is to explore influences of F. oxysporum invasion on the microbial community and to screen efficient biocontrol agents from microorganisms with changing relative abundance.ResultsIn this study, we evaluated that responses of the soil microbial communities to invasion of F. oxysporum. We found that F. oxysporum invasion could modify soil physical-chemical properties, soil enzymes activities, microbial community structure and diversity of the soil microbes. We screened and identified an efficient biocontrol strain, Talaromyces purpurogenus Q2, which could be used for defense and suppression of F. oxysporum in bitter gourd and efficiently decreasing incidence of the Fusarium wilt of bitter gourd in the greenhouse and in the field. The research results of biocontrol mechanisms showed that T. purpureogenus strain Q2 involved in the resistance of soil microbial communities to invasion of F. oxysporum, and the density of F. oxysporum was inhibited by exogenous T. purpureogenus and the resident microbes that strain Q2 promoted their growth. In the co-culture of strain Q2 and F. oxysporum, we further observed that T. purpurogenus Q2 could significantly suppress the mycelia growth and development of F. oxysporum by secreting cell wall degrading enzymes, and hinder cell wall formation by suppressing the gene expression of cell wall biosynthesis, such as FomCFEM that is essential for full virulence and stress tolerance in F. oxysporum.ConclusionTogether we screened a efficient biocontrol agents from microorganisms with resistance to the invasion of F. oxysporum. The mechanisms of Talaromyces purpurogenus strain Q2 protected bitter gourd from F. oxysporum is to reduce the relative abundance of rhizospheric F. oxysporum by inhibiting the growth and development of F. oxysporum. This work can provide a new biocontrol agent for biocontrol of Fusarium wilt and soil-born diseases of other horticultural crops.