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17 pages, 9847 KB

Open AccessArticle

Characteristics and Biocontrol Activity of Soil Bacterial Isolates Against the Emerging Pathogen Fusarium solani in Thai Durian (Durio zibethinus)

by Parima Boontanom, Praphaphorn Prasertsit, Sukitta Kosol, Taweesak Srithong and Aiya Chantarasiri

Microbiol. Res. 2026, 17(6), 112; https://doi.org/10.3390/microbiolres17060112 - 8 Jun 2026

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Abstract

Fusarium solani is an emerging pathogen responsible for Fusarium-related diseases in durian trees in Thailand. Several chemical fungicides and biocontrol agents are ineffective in controlling these diseases, which affects durian trees and reduces yields. This study aimed to identify soil-derived bacteria with [...] Read more.

Fusarium solani is an emerging pathogen responsible for Fusarium-related diseases in durian trees in Thailand. Several chemical fungicides and biocontrol agents are ineffective in controlling these diseases, which affects durian trees and reduces yields. This study aimed to identify soil-derived bacteria with biocontrol activity against F. solani that surpasses traditional biocontrol bacteria. The characteristics and biocontrol efficacy of effective isolates were analyzed. Four isolates from 107 bacterial isolates were identified as effective biocontrol agents against F. solani. Isolate S301 exhibited the highest inhibition at 74.31%, exceeding that of the traditional biocontrol bacterium Bacillus subtilis. These isolates antagonized F. solani by producing siderophores, fungal cell wall lytic enzymes, and hydrogen cyanide, and by promoting plant growth. Molecular and phylogenetic analyses identified the four isolates as members of the Bacillus genus, specifically B. safensis, B. thuringiensis, B. subtilis, and B. cereus. The application of B. safensis strain S101 and B. subtilis strain S301 showed potential to reduce fungal disease symptoms on Monthong durian leaves. These findings are the first to demonstrate the potential of B. safensis and B. subtilis as promising bacterial biocontrol agents for managing F. solani-related diseases in durian trees in Thailand. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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17 pages, 842 KB

Open AccessArticle

Bioactivity of Pod and Seed Extracts from Leucaena leucocephala, Prosopis laevigata, and Pithecellobium dulce Collected in Oaxaca, Mexico

by Jesús Andres Morales-López, Teodulfo Aquino-Bolaños, Angélica Bautista-Cruz, Tamara Aquino-Aguilar, Edgar García-Sánchez, Tlacaelel Aquino-López and Keyla Cruz-García

Microbiol. Res. 2026, 17(5), 97; https://doi.org/10.3390/microbiolres17050097 - 19 May 2026

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Abstract

Guaje (Leucaena leucocephala), mezquite (Prosopis laevigata), and guamuchil (Pithecellobium dulce) are leguminous trees distributed throughout southeastern Mexico. Their pods and seeds constitute the main agroecological residues and represent a natural source of secondary metabolites with high biotechnological [...] Read more.

Guaje (Leucaena leucocephala), mezquite (Prosopis laevigata), and guamuchil (Pithecellobium dulce) are leguminous trees distributed throughout southeastern Mexico. Their pods and seeds constitute the main agroecological residues and represent a natural source of secondary metabolites with high biotechnological potential. The aim of this study was to determine the chemical composition, antimicrobial and antioxidant activities, and toxicity of the pods and seeds of L. leucocephala, P. laevigata, and P. dulce. It was found that pod extracts contained higher concentrations of phenolic compounds, flavonoids, and terpenes than seed extracts. Antimicrobial assays showed inhibition zones ranging from 8.1–14.7 mm (E. coli), 8.8–15.1 mm (S. aureus), 11.3–15.4 mm (E. faecalis), 8.9–24.1 mm (C. albicans), and 8.5–22.6 mm (C. krusei). The ethyl acetate (AVPD) and ethanolic (EVPD) extracts from P. dulce pods showed the highest antimicrobial activity, with MIC values ranging from 0.03 to 0.15 mg/mL, MBC values of 0.07 mg/mL (S. aureus and E. faecalis), and MFC values of 1.25 mg/mL (C. albicans) and 0.62 mg/mL (C. krusei). Antioxidant activity was higher in pod extracts, with AVPD and EVPD showing IC₅₀ values of 0.257 and 0.320 mg/mL, respectively. Consistently, EVPD exhibited the highest phenolic content (133.24 mg GAE/g) and flavonoid content (50.90 mg QE/g), followed by AVPD (87.29 mg GAE/g and 42.40 mg QE/g, respectively). The results indicate that pod extracts of L. leucocephala and P. dulce contain secondary metabolites with broad antimicrobial and antioxidant potential and low toxicity. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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13 pages, 5857 KB

Open AccessArticle

Detection and Host Range Investigation of Phytopythium helicoides and Phytopythium palingenes

by Petya Koeva Christova

Microbiol. Res. 2026, 17(5), 90; https://doi.org/10.3390/microbiolres17050090 - 30 Apr 2026

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Abstract

Phytopythium species are water molds that have been divided as a separate group of oomycetes about 10 years ago. They are associated with diverse environments worldwide, but the ecological function of most of the species is still under investigation. In the present study, [...] Read more.

Phytopythium species are water molds that have been divided as a separate group of oomycetes about 10 years ago. They are associated with diverse environments worldwide, but the ecological function of most of the species is still under investigation. In the present study, isolation and characterization of Pp. helicoides and Pp. palingenes are described. Both Phytopythium isolates originate from an aquatic environment and were derived from infected leaves. A host range of Pp. helicoides and Pp. palingenes using pathogenicity tests with leaves and cuttings from trees, bushes, perennial and herbaceous plants that belong to 15 different families was studied. Out of 21 tested plants, 18 were susceptible to infection with Pp. helicoides and nine were negatively affected by Pp. palingenes. Pp. helicoides is distinguished by higher aggressiveness and a wider range of potential host species. These results indicate that the impact of pathogenic species from the genus Phytopythium on forests and other natural ecosystems could be much more significant than is currently known. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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22 pages, 1579 KB

Open AccessArticle

Grape-Associated Yeasts as Promising Antagonists Against Fungal Pathogens

by Tamar Maghradze, Alessandra Di Canito, Carmen Cris De Oliveira Nobre Bezerra, Mathabatha Evodia Setati, Roberto Carmine Foschino, Daniela Fracassetti and Ileana Vigentini

Microbiol. Res. 2026, 17(2), 32; https://doi.org/10.3390/microbiolres17020032 - 2 Feb 2026

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Abstract

Biocontrol, a practice for using living organisms to target plant pathogens, offers a promising, sustainable agricultural strategy. This study involves epiphytic yeasts isolated from Vitis vinifera ssp. sylvestris and ssp. vinifera as natural antagonists against Aspergillus carbonarius, Botrytis cinerea, and Penicillium [...] Read more.

Biocontrol, a practice for using living organisms to target plant pathogens, offers a promising, sustainable agricultural strategy. This study involves epiphytic yeasts isolated from Vitis vinifera ssp. sylvestris and ssp. vinifera as natural antagonists against Aspergillus carbonarius, Botrytis cinerea, and Penicillium expansum. Twenty-one of 37 yeasts were chosen based on the Pathology Intensity (PA) score during preliminary in vivo screening. Following identification, dual-culture assays, VOC production, copper tolerance, and commercial fungicide resistance were assessed. On YPD and GJ medium, Saccharomyces isolates were the strongest antagonists, whereas P. terricola UMY197 inhibited Penicillium and Aspergillus. H. uvarum UMY1473 was notably effective against B. cinerea. VOC analysis confirmed that S. cerevisiae UMY1430 was the most effective against Aspergillus, likely owing to its production of oxalic acid, while S. cerevisiae UMY1438 was a producer of various esters and phenylethyl alcohol. C. intermedia UMY189, M. pulcherrima UMY1472, H. uvarum UMY1473, and S. cerevisiae UMY1436 were the most copper-resistant. Yeast activity on chemical fungicide SWITCH (up to 1 g/L) depended on culture media usage; in fact, a higher viability on YPD than on GJ was observed, where only 4 yeasts were able to grow. Thus, since several yeasts exhibit promising inhibitory activity through various mechanisms and against different molds, the use of synthetic consortia could represent a powerful and essential tool in field trials to limit fungicide use while preventing the emergence of resistance. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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16 pages, 3467 KB

Open AccessArticle

Monoxenic Root Organ Culture Enables High-Yield Production of Viable Indigenous Rhizophagus irregularis Inoculum for Arid Oasis Agroecosystems

by Elmostafa Gagou, Hanae El Yeznasni, Wissame Chafai, Khadija Chakroune, Mahmoud Abbas, Touria Lamkami, Mondher El Jaziri and Abdelkader Hakkou

Microbiol. Res. 2026, 17(1), 28; https://doi.org/10.3390/microbiolres17010028 - 22 Jan 2026

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Abstract

Arbuscular mycorrhizal fungi (AMF) play a pivotal role in plant adaptation to arid ecosystems, yet their widespread agricultural use is constrained by the scarcity of high-quality, locally adapted inoculum. This study established a reliable monoxenic culture system for mass-producing an indigenous AMF isolate [...] Read more.

Arbuscular mycorrhizal fungi (AMF) play a pivotal role in plant adaptation to arid ecosystems, yet their widespread agricultural use is constrained by the scarcity of high-quality, locally adapted inoculum. This study established a reliable monoxenic culture system for mass-producing an indigenous AMF isolate from the date palm (Phoenix dactylifera L.) rhizosphere in the Figuig oasis, southeastern Morocco. The isolate was identified as Rhizophagus irregularis based on spore morphology and Large Subunit ribosomal DNA (LSU rDNA) phylogeny. Two propagule types, surface-sterilized spores and mycorrhizal root fragments of Plantago lanceolata L., were compared for initiation of in vitro cultures on Ri T-DNA-transformed carrot (Daucus carota L.) hairy roots. By week 16, cultures initiated from mycorrhizal root fragments produced 1414 ± 65 spores per plate and showed significantly higher performance than spore-derived cultures in terms of propagule viability, root colonization, and hairy root growth. Propagule viability reached 84% and 68%, root colonization frequencies were 95% and 72%, and hairy root lengths averaged 81 and 63 cm in root fragment- and spore-derived cultures, respectively (p < 0.01). In a subsequent whole-plant assay using P. lanceolata, in vitro-produced spores induced markedly higher mycorrhizal colonization frequency (91.0 ± 1.6% compared with 74.8 ± 1.9%) and intensity (70.0 ± 1.6% compared with 55.0 ± 1.6%) than spores obtained from conventional trap cultures (p < 0.001). These results demonstrate that monoxenic root-organ culture using root fragments is a robust, reproducible method for generating abundant, contaminant-free, and functionally superior inoculum of native R. irregularis. This advance provides a solid platform for developing tailored bio-inoculants to enhance crop resilience and sustainability in arid and semi-arid agroecosystems. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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17 pages, 1596 KB

Open AccessArticle

Whole-Genome Sequencing and Genomic Features of Vagococcus sp. JNUCC 83 Isolated from Camellia japonica Flowers

by Kyung-A Hyun, Ji-Hyun Kim, Min Nyeong Ko and Chang-Gu Hyun

Microbiol. Res. 2026, 17(1), 23; https://doi.org/10.3390/microbiolres17010023 - 18 Jan 2026

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Abstract

Vagococcus species have been isolated from diverse environments, including aquatic, terrestrial, food-associated, and clinical sources; however, plant- and flower-associated representatives remain poorly characterized at the genomic level. In this study, we report the complete genomic sequence and analysis of Vagococcus sp. JNUCC 83, [...] Read more.

Vagococcus species have been isolated from diverse environments, including aquatic, terrestrial, food-associated, and clinical sources; however, plant- and flower-associated representatives remain poorly characterized at the genomic level. In this study, we report the complete genomic sequence and analysis of Vagococcus sp. JNUCC 83, isolated from flowers of Camellia japonica collected on Jeju Island, Republic of Korea. The genome comprises a single circular chromosome of 2,472,896 bp with a GC content of 33.5 mol% and was assembled at high depth (555.43×), resulting in a high-quality complete genome. Genome-based phylogenomic analysis using the Type (Strain) Genome Server (TYGS) showed that strain JNUCC 83 forms a distinct lineage within the genus Vagococcus. Digital DNA–DNA hybridization (dDDH) values were far below the 70% species threshold, and 16S rRNA gene-based phylogeny consistently supported its independent placement, suggesting that JNUCC 83 represents a previously undescribed genomic species. Functional annotation based on EggNOG/COG analysis indicated the enrichment of genes involved in core metabolism and genome maintenance, while antiSMASH analysis identified a terpene-precursor-type biosynthetic locus encoding a polyprenyl synthase. Overall, this study expands the genomic understanding of flower-associated Vagococcus lineages and provides a foundation for future investigations into their ecological roles and potential applications as plant-derived microbial resources. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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19 pages, 3831 KB

Open AccessArticle

Phenotypic, Pathogenic, and Genetic Diversity of Botrytis cinerea Isolates from Moroccan Vineyards

by Faical Aoujil, Chaimae El Ghdaich, Imane Hourmatallah, Hiba Yahyaoui, Majida Hafidi, Aziz Aziz and Khaoula Habbadi

Microbiol. Res. 2025, 16(10), 219; https://doi.org/10.3390/microbiolres16100219 - 5 Oct 2025

Cited by 1 | Viewed by 2080

Abstract

Gray mold, caused by Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana), is a major disease affecting Moroccan vineyards. However, limited information is available on the natural populations of this pathogen. In this study, 82 single-spore isolates collected from vineyards in two major [...] Read more.

Gray mold, caused by Botrytis cinerea Pers. Fr. (teleomorph: Botryotinia fuckeliana), is a major disease affecting Moroccan vineyards. However, limited information is available on the natural populations of this pathogen. In this study, 82 single-spore isolates collected from vineyards in two major wine-growing regions were evaluated for phenotypic, physiological, and molecular variability. The isolates exhibited differences in morphotypes, conidial size, and sclerotia production on PDA medium. Temperature significantly affected mycelial growth rate (mm d⁻¹). All isolates were virulent on grapevine leaves, showing varying levels of aggressiveness. Among the representative isolates, 20 were heterothallic and 2 were homothallic. Mating-type analysis revealed that 12% belonged to MAT1-1 and 75% to MAT1-2. Transposable element genotyping showed that the population was composed of 41.7% transposa, 29.2% vacuma, 16.7% Flipper-only, and 12.5% Boty-only. This work represents the first report on genotypic variation in B. cinerea populations from Moroccan vineyards. The findings provide new insights into the morphenotypic and genetic diversity of the pathogen and may support the development of improved strategies for disease management. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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12 pages, 1823 KB

Open AccessBrief Report

Functional Characterization of CfRgs2 Reveals Its Critical Role in Growth, Conidiation, Stress Response, and Virulence of Colletotrichum fructicola

by Yadi Liu, Qiuyue Hu and He Li

Microbiol. Res. 2026, 17(3), 53; https://doi.org/10.3390/microbiolres17030053 - 2 Mar 2026

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Abstract

Colletotrichum fructicola is the predominant pathogenic agent responsible for anthracnose in Camellia oleifera. RGS2 is a GTPase-activating protein that negatively regulates G-protein signaling by inactivating Gα subunits. In this study, we characterized the ortholog of CfRGS2 in C. fructicola to explore its [...] Read more.

Colletotrichum fructicola is the predominant pathogenic agent responsible for anthracnose in Camellia oleifera. RGS2 is a GTPase-activating protein that negatively regulates G-protein signaling by inactivating Gα subunits. In this study, we characterized the ortholog of CfRGS2 in C. fructicola to explore its pathogenic roles. Seven canonical RGS genes were identified through BLASTp and keyword searches. Conserved domains and subcellular localizations were predicted bioinformatically. A CfRGS2 knockout mutant was generated via overlap-PCR and PEG-mediated transformation, verified by PCR, and complemented by reintroducing the wild-type gene. Phenotypic characterization showed that the growth rates of mutants ΔCfrgs2-1 and ΔCfrgs2-2 were significantly reduced compared with those of the wild-type and complemented strains. On both PDA and minimal medium, the mutant strains exhibited significantly smaller colony diameters of 3.3 cm and 3.1 cm, respectively, relative to the control strains. Moreover, conidiation in the mutants was only 4% of that in the wild-type and complemented strains, and appressorium formation was reduced to 6%, with statistical analyses confirming high significance. Under cell wall stress induced by 400 μg/mL Congo red, the growth inhibition rates of ΔCfrgs2-1 and ΔCfrgs2-2 were 44% and 48%, respectively, significantly higher than those of the control strains. Pathogenicity assays demonstrated that the mutants failed to induce lesions on unwounded leaves and caused 47% and 30% smaller lesion areas on wounded apple fruits, respectively. In summary, C. fructicola possesses seven canonical RGS proteins that regulate G-protein signaling, among which CfRgs2 is implicated in growth, conidiation, the stress response to cell wall perturbation, and virulence. Full article

(This article belongs to the Special Issue Advances in Plant–Pathogen Interactions)

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