Conjugation of antifungal benzoic acid derivatives as a path for detoxification in Penicillium brasilianum, an endophyte from Melia azedarach

Biotransformation ability of endophytic fungi: from species evolution to industrial applications

Increased understanding of the interactions between endophytic fungi and plants has led to the discovery of a new generation of chemical compounds and processes between endophytic fungi and plants. Due to the long-term co-evolution between fungal endophytes and host plants, endophytes have evolved special biotransformation abilities, which can have critical consequences on plant metabolic processes and their composition. Biotransformation or bioconversion can impact the synthesis and decomposition of hormones, sugars, amino acids, vitamins, lipids, proteins, and various secondary metabolites, including flavonoids, polysaccharides, and terpenes. Endophytic fungi produce enzymes and various bioactive secondary metabolites with industrial value and can degrade or sequester inorganic and organic small molecules and macromolecules (e.g., toxins, pollutants, heavy metals). These fungi also have the ability to cause highly selective catalytic conversion of high-value compounds in an environmentally friendly manner, which can be important for the production/innovation of bioactive molecules, food and nutrition, agriculture, and environment. This work mainly summarized recent research progress in this field, providing a reference for further research and application of fungal endophytes. KEY POINTS: •The industrial value of degradation of endophytes was summarized. • The commercial value for the pharmaceutical industry is reviewed.

Bioconversion of antifungal viridin to phytotoxin viridiol by environmental non-viridin producing microorganisms

Biotransformation of viridin, an antifungal produced by biocontrol agent, with non-viridin producing microorganisms is studied. The results show that some environmental non-targeted microorganisms are able to reduce it in the known phytotoxin viridiol, and its 3-epimer. Consequently, this reduction, which happens in some cases by detoxification mechanism, could be disastrous for the plant in a biocontrol of plant disease. However, a process fermentation/biotransformation could be an efficient approach for the preparation of this phytotoxin.

Disarming the Host: Detoxification of Plant Defense Compounds During Fungal Necrotrophy

While fungal biotrophs are dependent on successfully suppressing/subverting host defenses during their interaction with live cells, necrotrophs, due to their lifestyle are often confronted with a suite of toxic metabolites. These include an assortment of plant defense compounds (PDCs) which can demonstrate broad antifungal activity. These PDCs can be either constitutively present in plant tissue or induced in response to infection, but are nevertheless an important obstacle which needs to be overcome for successful pathogenesis. Fungal necrotrophs have developed a number of strategies to achieve this goal, from the direct detoxification of these compounds through enzymatic catalysis and modification, to the active transport of various PDCs to achieve toxin sequestration and efflux. Studies have shown across multiple pathogens that the efficient detoxification of host PDCs is both critical for successful infection and often a determinant factor in pathogen host range. Here, we provide a broad and comparative overview of the various mechanisms for PDC detoxification which have been identified in both fungal necrotrophs and fungal pathogens which depend on detoxification during a necrotrophic phase of infection. Furthermore, the effect that these mechanisms have on fungal host range, metabolism, and disease control will be discussed.

Microbial Biotransformation of Iridoid Glycosides from Gentiana Rigescens by Penicillium Brasilianum

This study aimed to investigate the metabolic effects of endophytic fungi in Gentiana rigescens. From the 100 selected morphospecies, strain 7-2 (Penicillium brasilianum) showed a remarkable biocatalytic activity for gentiopicroside and swertiamarin, yielding seven products, including one new compound, 5-ethylidene-8-hydroxy-4,5,6,8-tetrahydropyrano[3,4-c]pyran-1-one (M04), alongside six known compounds. Gentianine (M01) was the only metabolite of swertiamarin in this study, while the remaining ones were all gentiopicroside metabolites. Among these, five compounds: gentianine (M01), (5S,6S)-5-(hydroxymethyl)-6-methyl-5,6-dihydro-1H,3H-pyrano[3,4-c]pyran-1-one (M02), (5R,6S)-5-(hydroxymethyl)-6-methyl-5,6-dihydro-1H,3H-pyrano[3,4-c]pyran-1-one (M03), 2-(3-formyl-2-oxo-3,6-dihydro-2H-pyran-4-yl)but-3-enoic acid (M06), and 2-oxo-4-(1-oxobut-3-en-2-yl)-3,6-dihydro-2H-pyran-3-carboxylic acid (M07) were similar to gentiopicroside metabolites in humans. Screening the metabolic potential of endophytic fungi in Gentiana rigescens provides an outstanding source for assessing the bioactive metabolites of iridoid glycosides. The above findings suggested that the endophytic fungi of G. rigescens possess multi-enzyme systems that mimic metabolic reactions in mammalian organisms.

Virulence Factors in the Phytopathogen-Host Interactions: An Overview

Phytopathogens are responsible for great losses in agriculture, once they are able to subvert or elude the host defense mechanisms through virulence factors secretion for their dissemination. Herein, it is reviewed phytotoxins that act as virulence factors and are produced by bacterial phytopathogens (Candidatus Liberibacter spp., Erwinia amylovora, Pseudomonas syringae pvs and Xanthomonas spp.) and fungi (Alternaria alternata, Botrytis cinerea, Cochliobolus spp., Fusarium spp., Magnaporthe spp., and Penicillium spp.), which were selected in accordance to their worldwide importance due to the biochemical and economical aspects. In the current review, it is sought to understand the role of virulence factors in the pathogen-host interactions that result in plant diseases.