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4 pages, 133 KiB

Open AccessEditorial

Plant Pathogenic Fungi Special Issue: Genetics and Genomics

by Micael F. M. Gonçalves

Microorganisms 2025, 13(4), 925; https://doi.org/10.3390/microorganisms13040925 - 17 Apr 2025

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Abstract

Plant pathogenic fungi pose a significant challenge to global agriculture, threatening crop yields, food security, and ecosystem stability [...] Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

Research

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14 pages, 1103 KiB

Open AccessArticle

Pathotypes and Simple Sequence Repeat (SSR)-Based Genetic Diversity of Phytophthora sojae Isolates in the Republic of Korea

by Ngoc Ha Luong, In-Jeong Kang, Hee Jin You and Sungwoo Lee

Microorganisms 2025, 13(3), 478; https://doi.org/10.3390/microorganisms13030478 - 21 Feb 2025

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Abstract

Phytophthora sojae is the causal agent of the Phytophthora root and stem rot in soybean, which has resulted in a significant increase in the incidence of the disease and substantial yield losses on a global scale. The proliferation of Phytophthora sojae can be mitigated [...] Read more.

Phytophthora sojae is the causal agent of the Phytophthora root and stem rot in soybean, which has resulted in a significant increase in the incidence of the disease and substantial yield losses on a global scale. The proliferation of Phytophthora sojae can be mitigated through the development of Phytophthora-resistant soybean cultivars. A fundamental understanding of the genetic diversity and dynamic changes within the P. sojae population is essential for disease management and the development of new P. sojae-resistant varieties. Although a large number of pathogen samples can lead to more comprehensive interpretations and better conclusions, only six indigenous P. sojae isolates were available in the Republic of Korea at the time of the experiments. Due to the limited availability, this study preliminarily aimed to assess the pathotypes and genetic variation of the six P. sojae isolates collected in the Republic of Korea. The virulence patterns of all the six P. sojae isolates differed based on the 15 soybean differentials known for P. sojae resistance. The six isolates displayed high levels of pathotype complexities, ranging from 8 to 15, which is notably higher than those observed in other countries. Furthermore, 18 of the 21 simple sequence repeat markers used exhibited polymorphisms. The mean allele number (3.8) shows higher genetic variability compared to that (2.5) of isolates from the USA. The gene diversity (0.624) and the mean polymorphic information content (0.579) also displayed high levels of variation among the six isolates. A low mean heterozygosity (0.019) indicated a rare but possible outcrossing between the isolates, which was detected by the SSR marker PS07. Genetic dissimilarity assessments were employed to categorize the six P. sojae isolates into three groups using a neighbor-joining phylogenetic tree and principal component analysis. Although on a small scale, the phenotypic and genotypic assay results obtained indicated a significant variability in the pathotypes and genetic variation within the P. sojae isolates in the Republic of Korea. Though limited in scope, these results will be a cornerstone for elucidating the virulence pathotype and genetic diversity of the P. sojae population in future analyses. These findings also have the potential to improve the soybean breeding strategies aimed at enhancing resistance to P. sojae in the Republic of Korea. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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13 pages, 3729 KiB

Open AccessArticle

A Cytochrome P450 AaCP1 Is Required for Conidiation and Pathogenicity in the Tangerine Pathotype of Alternaria alternata

by Huilan Fu, Wenge Li and Jintian Tang

Microorganisms 2025, 13(2), 343; https://doi.org/10.3390/microorganisms13020343 - 5 Feb 2025

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Abstract

Citrus Alternaria brown spot caused by the necrotrophic fungal pathogen of the tangerine pathotype of Alternaria alternata causes yield losses in global tangerine production. In this study, we focus on a cytochrome P450 monooxygenase encoding gene, Aacp1, for its role in the [...] Read more.

Citrus Alternaria brown spot caused by the necrotrophic fungal pathogen of the tangerine pathotype of Alternaria alternata causes yield losses in global tangerine production. In this study, we focus on a cytochrome P450 monooxygenase encoding gene, Aacp1, for its role in the sporulation, toxin production, and virulence of the tangerine pathotype of Alternaria alternata. Aacp1-deficient mutants (∆Aacp1) produced significantly fewer conidia than the wild-type strain. Chemical assays demonstrated that Aacp1 plays a negative role in resistance to oxidant stress and biosynthesis of ACT toxin. Virulence assays revealed that ΔAacp1 fails to induce necrotic lesions on detached Hongjv leaves. Transcriptomic analyses of WT and ΔAacp1 revealed that many metabolic process genes were regulated. Furthermore, our results revealed a previously unrecognized Aacp1 affected the expression of the gene encoding a naphthalene dioxygenase (AaNdo1) for sporulation and full virulence. Overall, this study revealed the diverse functions of cytochrome P450 monooxygenase in the phytopathogenic fungus. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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13 pages, 3875 KiB

Open AccessArticle

First Report on the Emergence of Neopestalotiopsis rosae as a Severe Economic Threat to Strawberry Production in Germany

by Tom E. Schierling, Ralf T. Voegele and Abbas El-Hasan

Microorganisms 2025, 13(1), 6; https://doi.org/10.3390/microorganisms13010006 - 24 Dec 2024

Cited by 1 | Viewed by 1041

Abstract

Strawberries hold significant economic importance in both German and global agriculture. However, their yield is often adversely affected by fungal diseases. This study describes Neopestalotiopsis rosae as a newly emerging pathogen responsible for leaf blight and fruit rot in strawberries in Germany. Infected [...] Read more.

Strawberries hold significant economic importance in both German and global agriculture. However, their yield is often adversely affected by fungal diseases. This study describes Neopestalotiopsis rosae as a newly emerging pathogen responsible for leaf blight and fruit rot in strawberries in Germany. Infected plants were observed in Hohenheim, Germany. A combination of morphological and molecular analyses, along with pathogenicity tests, confirmed the identity of N. rosae as the causal agent. Morphological examination of conidia and mycelium revealed key characteristics including the presence of versicolorous median cells, conidial appendages, black spherical conidiomata formation as well as changing colony color and fluffy texture. These properties align with the established descriptions for the species. Molecular analysis, particularly the sequencing of the internal transcribed spacer and β-tubulin regions allowed the precise identification of the pathogen. Artificial inoculation of healthy strawberry plants with conidial suspension derived from the isolated strain resulted in the development of characteristic symptoms, including necrotic leaf spots and water-soaked fruit lesions, similar to those observed on the original infected plants. To our knowledge, this study presents the first documented occurrence of N. rosae in Germany, highlighting its emergence as a significant threat to strawberry production in Europe. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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13 pages, 1917 KiB

Open AccessArticle

Etiology of Foliar Blight of Indian Paintbrush (Castilleja tenuiflora) in Mexico

by Alma Rosa Solano-Báez, Gabriela Trejo-Tapia, Miroslav Kolařík, Jossue Ortiz-Álvarez, José Luis Trejo-Espino and Guillermo Márquez-Licona

Microorganisms 2024, 12(8), 1714; https://doi.org/10.3390/microorganisms12081714 - 20 Aug 2024

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Abstract

Castilleja tenuiflora is a native perennial plant used in traditional Mexican medicine. In June 2022, leaf blight symptoms were observed in a wild population of C. tenuiflora plants. Disease incidence was 80% and disease intensity reached up to 5% of the leaf area. [...] Read more.

Castilleja tenuiflora is a native perennial plant used in traditional Mexican medicine. In June 2022, leaf blight symptoms were observed in a wild population of C. tenuiflora plants. Disease incidence was 80% and disease intensity reached up to 5% of the leaf area. Currently, there are no reports of pathogens causing leaf blight in this plant; therefore, this work aimed to identify the fungi responsible for the disease. The fungi recovered from the diseased tissue were characterized by means of pathogenicity tests and cultural, morphological, and molecular characterization. The information obtained revealed that Alternaria alternata and Alternaria gossypina are the pathogens responsible for the disease. This is the first report implicating species of Alternaria in causing leaf blight of C. tenuiflora in Mexico, as well as the first report of Alternaria gossypina also in Mexico. These pathogens may threaten the in situ conservation of native C. tenuiflora populations and limit their in vitro propagation. Future research lines should focus on determining the effect of these pathogens on metabolite production. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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8 pages, 600 KiB

Open AccessCommunication

In Vitro Assay Using Proboscidea parviflora W. and Phaseolus lunatus L. Plant Extracts to Control Pythium amazonianum

by Yisa María Ochoa Fuentes, Antonio Orozco Plancarte, Ernesto Cerna Chávez and Rocío de Jesús Díaz Aguilar

Microorganisms 2024, 12(6), 1045; https://doi.org/10.3390/microorganisms12061045 - 22 May 2024

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Abstract

Avocado tree wilt is a disease caused by Phytophthora cinnamomi Rands. Recently, this disease has been associated to Pythium amazonianum, another causal agent. Avocado tree wilt is being currently controlled with synthetic fungicides that kill beneficial microorganisms, polluting the environment and leading [...] Read more.

Avocado tree wilt is a disease caused by Phytophthora cinnamomi Rands. Recently, this disease has been associated to Pythium amazonianum, another causal agent. Avocado tree wilt is being currently controlled with synthetic fungicides that kill beneficial microorganisms, polluting the environment and leading to resistance problems in plant pathogens. The current research work aims to provide alternative management using extracts from Proboscidea parviflora W. and Phaseolus lunatus L. to control the development of mycelia in P. amazonianum in vitro. Raw extracts were prepared at UAAAN Toxicology Laboratory, determining the inhibition percentages, inhibition concentrations and inhibition lethal times. Several concentrations of the plant extracts were evaluated using the poisoned medium methodology, showing that both extracts control and inhibit mycelial development, in particular P. lutatus, which inhibits mycelial growth at concentrations lower than 80 mg/L, being lower than P. parviflora extracts. These extracts are promising candidates for excellent control of Pythium amazonianum. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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17 pages, 2823 KiB

Open AccessArticle

Tolerance Evaluation of Celery Commercial Cultivars and Genetic Variability of Fusarium oxysporum f. sp. apii

by Mónica Blanco-Meneses, Mauricio Serrano-Porras, Anny Calderón-Abarca, Alejandro Sebiani-Calvo, Gabriel Vargas and Oscar Castro-Zúñiga

Microorganisms 2023, 11(11), 2732; https://doi.org/10.3390/microorganisms11112732 - 9 Nov 2023

Cited by 1 | Viewed by 1750

Abstract

Celery (Apium graveolens var. dulce) is affected by several plant diseases, such as Fusarium oxysporum f. sp. apii (Foa). Four Foa races have been found in the US. The goals of this study were to determine which races are present in Costa [...] Read more.

Celery (Apium graveolens var. dulce) is affected by several plant diseases, such as Fusarium oxysporum f. sp. apii (Foa). Four Foa races have been found in the US. The goals of this study were to determine which races are present in Costa Rica and to quantify the tolerance of the imported commercial cultivars of celery produced in the country. Isolates from 125 symptomatic celery plants from three different geographical locations were analyzed, 65 of which were selected for phylogenetic analysis. All isolates presented a short sequence of five nucleotides that differentiates Foa race 3 in the IGS rDNA region. Three different haplotypes closely related to race 3 were found, which were highly virulent, produced great losses, and affected all cultivars (resistant to races 2 and 4) of imported commercial celery. Additionally, five different cultivars of celery were evaluated against seven pathogen isolates identified as race 3 in greenhouse conditions. Two of the cultivars showed significantly less chlorosis, wilting, mortality, and higher fresh weight. Most of the Foa isolates significantly increased chlorosis, wilting, and mortality compared to non-inoculated control. Celery producers in Costa Rica lack access to seeds resistant to the Foa race 3 present in the country. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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62 pages, 6166 KiB

Open AccessArticle

Diaporthe Species on Palms: Molecular Re-Assessment and Species Boundaries Delimitation in the D. arecae Species Complex

by Diana S. Pereira, Sandra Hilário, Micael F. M. Gonçalves and Alan J. L. Phillips

Microorganisms 2023, 11(11), 2717; https://doi.org/10.3390/microorganisms11112717 - 6 Nov 2023

Cited by 15 | Viewed by 2842

Abstract

Due to cryptic diversification, phenotypic plasticity and host associations, multilocus phylogenetic analyses have become the most important tool in accurately identifying and circumscribing species in the Diaporthe genus. However, the application of the genealogical concordance criterion has often been overlooked, ultimately leading to [...] Read more.

Due to cryptic diversification, phenotypic plasticity and host associations, multilocus phylogenetic analyses have become the most important tool in accurately identifying and circumscribing species in the Diaporthe genus. However, the application of the genealogical concordance criterion has often been overlooked, ultimately leading to an exponential increase in novel Diaporthe spp. Due to the large number of species, many lineages remain poorly understood under the so-called species complexes. For this reason, a robust delimitation of the species boundaries in Diaporthe is still an ongoing challenge. Therefore, the present study aimed to resolve the species boundaries of the Diaporthe arecae species complex (DASC) by implementing an integrative taxonomic approach. The Genealogical Phylogenetic Species Recognition (GCPSR) principle revealed incongruences between the individual gene genealogies. Moreover, the Poisson Tree Processes’ (PTPs) coalescent-based species delimitation models identified three well-delimited subclades represented by the species D. arecae, D. chiangmaiensis and D. smilacicola. These results evidence that all species previously described in the D. arecae subclade are conspecific, which is coherent with the morphological indistinctiveness observed and the absence of reproductive isolation and barriers to gene flow. Thus, 52 Diaporthe spp. are reduced to synonymy under D. arecae. Recent population expansion and the possibility of incomplete lineage sorting suggested that the D. arecae subclade may be considered as ongoing evolving lineages under active divergence and speciation. Hence, the genetic diversity and intraspecific variability of D. arecae in the context of current global climate change and the role of D. arecae as a pathogen on palm trees and other hosts are also discussed. This study illustrates that species in Diaporthe are highly overestimated, and highlights the relevance of applying an integrative taxonomic approach to accurately circumscribe the species boundaries in the genus Diaporthe. Full article

(This article belongs to the Special Issue Plant Pathogenic Fungi: Genetics and Genomics)

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