Extracts from Environmental Strains of Pseudomonas spp. Effectively Control Fungal Plant Diseases

Abstract

The use of synthetic chemical products in agriculture is causing severe damage to the environment and human health, but agrochemicals are still widely used to protect our crops. To counteract this trend, we have been looking for alternative strategies to control plant diseases without causing harm to the environment or damage to our health. However, these alternatives are still far from completely replacing chemical products. Microorganisms have been widely known as a biological tool to control plant diseases, but their use is still limited due to the high variability in their efficacy, together with issues in product registration. However, the metabolites produced by these microorganisms can represent a novel tool for the environment-friendly management of plant diseases, while reducing the issues mentioned above. In this study, we explore the soil microbial diversity in natural systems to look for microorganisms with the potential to be used in pre- and post-harvest protection against fungal plant pathogens. Using a simple workflow, we isolated 22 bacterial strains that were tested both in vitro and in vivo for their ability to counteract the growth of common plant pathogens. The three best isolates, identified as members of the bacterial genus Pseudomonas, were used to produce a series of alcoholic extracts, which were then tested for their action against plant pathogens in simulated real-world applications. Results show that extracts from these isolates have an exceptional biocontrol activity and can be successfully used to control plant pathogens in operational setups. Thus, this study shows that the environmental microbiome is an important source of microorganisms producing metabolites that might provide an alternative strategy to synthetic chemical products.

The Isolate Pseudomonas multiresinivorans QL-9a Quenches the Quorum Sensing Signal and Suppresses Plant Soft Rot Disease

“…Recent studies have shown that a variety of Pseudomonas sp. are widely used as biological control agents and have the advantage of colonizing plant roots and inhibiting a variety of plant diseases [55][56][57][58][59]. They prevent and control plant diseases by producing pathogen-resisting agents, such as antibacterial metabolites, proteases, lipases, and chitinases [60][61][62].…”

Biotechnological and Biocontrol Approaches for Mitigating Postharvest Diseases Caused by Fungal Pathogens and Their Mycotoxins in Fruits: A Review

“…Another notable biocontrol agent is the bacterium Pseudomonas fluorescens . P. fluorescens has been extensively studied for its antagonistic activity against various postharvest fungal pathogens in fruits, including B. cinerea , P. expansum , and Monilinia spp . , It produces a range of secondary metabolites, such as phenazines and cyclic lipopeptides, which inhibit fungal growth and spore germination . For example, Kurniawan et al demonstrated that Pseudomonas effectively controlled gray mold caused by A. alternata and B. cinerea in postharvest strawberries, resulting in reduced disease severity and prolonged the fruit shelf life .…”

Paraburkholderia phytofirmans PsJN delays Botrytis cinerea development on grapevine inflorescences

“…Among these, plant growth promoting rhizobacteria are of great interest ( Lugtenberg and Kamilova, 2009 ) since they induce not only stimulation of plant growth but can also protect against pathogens ( Beneduzi et al, 2012 ). Different studies described biological control agents (BCAs) that protect grapevine against gray mold disease ( Abbey et al, 2019 ; Bruisson et al, 2019 ; Esmaeel et al, 2019 , 2020 ; Amarouchi et al, 2021 ; Librizzi et al, 2022 ). Previous work on grapevine in vitro -plantlets demonstrated that Paraburkholderia phytofirmans strain PsJN can protect leaves against Botrytis by a combined effect: defense priming and direct antifungal effect ( Miotto-Vilanova et al, 2016 ).…”