Mycoviruses infecting Colletotrichum spp.: A comprehensive review

Colletotrichum is one of the most economically important fungal genera, which affects a wide range of hosts, specifically tropical and subtropical crops. Thus far, there have been several records of mycovirus infection in Colletotrichum spp., primarily by viruses of the Partitiviridae family. There have also been records of infections by mycoviruses of the Chrysoviridae family. Mycoviruses are (+)ssRNA and dsRNA genome viruses, which may or may not be enveloped. To date, no mycovirus with a DNA genome has been isolated from Colletotrichum spp. Typically, mycoviruses cause latent infections, although hypo- and hypervirulence have also been reported in Colletotrichum spp. In addition to its effects on pathogenic behavior, mycovirus infection can lead to important physiological changes, such as altered morphological characteristics, reduced vegetative growth, and suppressed conidia production. Therefore, research on mycoviruses infecting phytopathogenic fungi can help develop alternative methods to chemical control, which can cause irreversible damage to humans and the environment. From an agricultural perspective, mycoviruses can contribute to sustainable agriculture as biological control agents via changes in fungal physiology, ultimately resulting in the total loss of or reduction in the virulence of these pathogens.

Recent Advances in Sorbicillinoids from Fungi and Their Bioactivities (Covering 2016–2021)

Sorbicillinoids are a family of hexaketide metabolites with a characteristic sorbyl side chain residue. Sixty-nine sorbicillinoids from fungi, newly identified from 2016 to 2021, are summarized in this review, including their structures and bioactivities. They are classified into monomeric, dimeric, trimeric, and hybrid sorbicillinoids according to their basic structural features, with the main groups comprising both monomeric and dimeric sorbicillinoids. Some of the identified sorbicillinoids have special structures such as ustilobisorbicillinol A, and sorbicillasins A and B. The majority of sorbicillinoids have been reported from fungi genera such as Acremonium, Penicillium, Trichoderma, and Ustilaginoidea, with some sorbicillinoids exhibiting cytotoxic, antimicrobial, anti-inflammatory, phytotoxic, and α-glucosidase inhibitory activities. In recent years, marine-derived, extremophilic, plant endophytic, and phytopathogenic fungi have emerged as important resources for diverse sorbicillinoids with unique skeletons. The recently revealed biological activities of sorbicillinoids discovered before 2016 are also described in this review.

Effect of Plant Growth Promoting Bacillus spp. on Germination and Seedling Growth of Soybean

Background: Bacillus spp., known to promote growth and reduce disease of various field and vegetable crops, are frequently found in soils. The objective of the study was to select effective Bacillus spp. isolates with multiple plant growth properties and antifungal activities and to examine their effect on germination of soybean. Methods: Bacterial isolates were screened for production of indole-3-acetic acid (IAA) and siderophores and solubilization of phosphate. The ability of bacterial isolates to inhibit the growth of seven phytopathogenic fungi affecting soybean was determined using a dual plate assay. Bacillus spp. were further selected and examined in a seed germination test. Result: All Bacillus spp. isolates were positive for IAA production, while siderophore production and P-solubilization were observed in 80% and 20% bacterial isolates, respectively. Bacillus spp. exhibited the highest antifungal activity against Diaporthe caulivora, followed by Diaporthe sojae, Diaporthe eres, Diaporthe longicolla and Macrophomina phaseolina and the least antagonistic effect toward Fusarium graminearum and Fusarium subglutinans. Selected isolates of B. subtilis significantly affected final germination, shoot length, root length, shoot dry weight and root dry weight of two soybean cultivars. The most effective Bacillus spp. isolates could be used as potential inoculants for improving soybean productivity.

A Metabolomic Study of Epichloë Endophytes for Screening Antifungal Metabolites

Epichloë endophytes, fungal endosymbionts of Pooidae grasses, are commonly utilized in forage and turf industries because they produce beneficial metabolites that enhance resistance against environmental stressors such as insect feeding and disease caused by phytopathogen infection. In pastoral agriculture, phytopathogenic diseases impact both pasture quality and animal production. Recently, bioactive endophyte strains have been reported to secrete compounds that significantly inhibit the growth of phytopathogenic fungi in vitro. A screen of previously described Epichloë-produced antifeedant and toxic alkaloids determined that the antifungal bioactivity observed is not due to the production of these known metabolites, and so there is a need for methods to identify new bioactive metabolites. The process described here is applicable more generally for the identification of antifungals in new endophytes. This study aims to characterize the fungicidal potential of novel, ‘animal friendly’ Epichloë endophyte strains NEA12 and NEA23 that exhibit strong antifungal activity using an in vitro assay. Bioassay-guided fractionation, followed by metabolite analysis, identified 61 metabolites that, either singly or in combination, are responsible for the observed bioactivity. Analysis of the perennial ryegrass-endophyte symbiota confirmed that NEA12 and NEA23 produce the prospective antifungal metabolites in symbiotic association and thus are candidates for compounds that promote disease resistance in planta. The “known unknown” suite of antifungal metabolites identified in this study are potential biomarkers for the selection of strains that enhance pasture and turf production through better disease control.

Perception of fungi by farmers in the Cerrado

Fungi are important in several aspects of human life. In particular, to agriculture, pathogenic fungi are of great importance, as they are responsible for production losses of the most diverse types. Because of this, knowledge about pathogenic fungus is of extreme importance for farmers and professionals working in agricultural areas. Among farmers who use specific agroecological practices, this knowledge is even more valuable, since by not adopting conventional methods of production, they resort to non-invasive alternatives that are less or not harmful at all to the environment in consideration of production management methods. This study aimed to assess farmer perception in the Cerrado biome in the city of Goiás (GO), Brazil, in order to understand their ethnomycological perceptions to verify historical management practices, their knowledge about phytopathogenic fungi, and how these producers perceive fungi. We used the theoretical reference method “From peasant to peasant” formulated by ANPA - National Association of Small Farmers. Some aspects of farmers’ ethnomycological knowledge are discussed. These ease identification the representatives of the Fungi Kingdom is associated with organisms that present easily recognizable characteristics, such as wood-ears or disease-causing fungi. In general, farmers are able to identify representatives of the Fungi Kingdom that are found in their daily lives. The perception of farmers about fungi, a group still much unknown by society, is very relevant for future actions of ethnomycology.

THE COMPOST, A SOURCE OF PLANT BENEFICIAL BACTERIA WITH BIOCONTROL POTENTIAL

Recycling the sewage sludge from treatment plants is a common activity. The resulting compost is usually rich in plant nutrients and beneficial microorganisms. However, compost properties greatly differ depending on the nature of the fermented biomass and fermentation processes. The aim of this study was to analyze the microbial load of three different composts, in order to detect new bacterial strains with plant protection properties. Isolated bacteria were microbiologically characterized and evaluated for their potential to reduce soil-borne phytopathogenic fungi. Results showed a microbial load of approximately 106 CFU/g of compost. In the analyzed samples it was revealed that as bacterial load increases, the fungal amount decreases. Analyzing some newly isolated bacteria obtained from these composts, a good biocontrol potential against soil-borne pathogenic fungi was revealed. Some of the isolated bacterial strains revealed antifungal activity against Rhizoctonia solani and Sclerotinia sclerotiorum. These bacteria showed good colonization capacity and lytic enzymes production, correlated to antimicrobial activity. These compost-originated bacteria reveal high potential in pathogens inhibition. Therefore, the analyzed composts are recommended not only as soil fertility improvers, but also as potential suppressors of soil-borne pathogens. Results revealed these composts as source of plant beneficial bacteria with biological control potential.

Thymol and its Derivatives for Management of Phytopathogenic fungi of maize

Background: Thymol is a bioactive compound having many pharmacological activities. Objective: The present study was carried out to evaluate the fungi toxic effects of thymol and derivatives against phytopathogenic fungi of maize. Method: Thymol was derivatized to get formylated thymol, Mannich bases, and imine derivatives. All the synthesized thymol derivatives were characterized by their physical and spectral properties. Synthesized thymol derivatives were screened for their in vitro antifungal effects using poisoned food technique against three maize pathogenic fungi namely Fusarium moniliforme, Rhizoctonia solani and Dreschlera maydis. Results: Thymol and formylated thymol showed promising results for control of D. maydis with ED50 values less than standard carbendazim and comparable to standard mancozeb. These two compounds were further evaluated for control of D. maydis causative maydis leaf blight disease on maize plants grown in the field during the Kharif season (June to October) 2018. Conclusion: Thymol exhibited significant control of maydis leaf blight disease of maize and emerged as a potential alternative to synthetic fungicides used in cereal crops.

Penicillium Amapaense sp. nov. Exilicaulis Section and New Records of Penicillium Labradorum in Brazil Isolated from Amazon River Sediments with Potential Applications in Agriculture and Biotechnology

The genus Penicillium is recognized for its ability to produce bioactive molecules with a wide range of biotechnological applications. Currently, the genus is distributed in 28 sections, with more than 50 species in the Exilicaulis section. Representative species of this section are responsible for the production of antimicrobial compounds, but they can also produce genotoxic compounds that affect commercial mushroom production or cause disease in immunosuppressed animals. In the present study, based on morphological characters such as the length of the conidia, phialides and stipes, as well as sequence analysis of the ITS region and partial sequence of CAM, TUB2 and RPB2 loci, we describe a new fungal species denominated Penicillium amapaense and report for the first time the occurrence of Penicillium labrodorum in Brazil, both of which were isolated from sediments of the Amazon River. The isolates obtained in this study for each species were submitted to antibiosis assays against 12 phytopathogenic fungi that affect important agricultural crops in Brazil and showed inhibition of 11 out of 12 of them. The production of amylase, cellulase and siderophore as well phosphate solubilization was also detected. Metabolomic analysis indicates the ability of P. labrodorum and Penicillium amapaense sp nov. to produce polyketides such as known curvularins and anthraquinones. In addition to these, unknown compounds were also detected. These results indicate the biotechnological and agricultural potential of P. labradorum and P. amapaense.