Research

15 pages, 2458 KiB

Open AccessArticle

Characterization of the Cassava Mycobiome in Symptomatic Leaf Tissues Displaying Cassava Superelongation Disease

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Angela Alleyne

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Shanice Mason

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Yvonne Vallès

J. Fungi 2023, 9(12), 1130; https://doi.org/10.3390/jof9121130 - 23 Nov 2023

Viewed by 415

Abstract

Superelongation disease (SED) is a fungal disease that affects cassava in the Caribbean. The symptoms include the appearance of dry necrotic spots and lesions on the leaves, which may severely affect the plant yield. However, the primary causal pathogen is difficult to culture [...] Read more.

Superelongation disease (SED) is a fungal disease that affects cassava in the Caribbean. The symptoms include the appearance of dry necrotic spots and lesions on the leaves, which may severely affect the plant yield. However, the primary causal pathogen is difficult to culture and isolate in the lab because of its slow growth and potential contamination from faster-growing organisms. In addition, the leaf symptoms can be confused with those caused by other pathogens that produce similar necrotic spots and scab-like lesions. There is also little or no information on the contribution of endophytes, if any, to disease symptoms in cassava, a plant where the disease is prevalent. Therefore, this study aimed to characterize the fungal communities in cassava associated with SED symptoms by analyzing gross fungal morphology and performing metagenomics profiling. First, several individual pathogenic fungi were isolated and cultured from diseased cassava leaf tissues from seven locations in Barbados (BB). Both culture isolation and molecular community analyses showed the presence of several other fungi in the disease microenvironment of symptomatic cassava leaves. These included Fusarium, Colletotrichum, and Alternaria species and the suspected species Elsinoë brasiliensis synonym Sphaceloma manihoticola. Additionally, a community analysis using ITS2 amplicon sequencing of 21 symptomatic leaf tissues from BB, St. Vincent and the Grenadines (SVG), Trinidad and Tobago (TT), and Jamaica (JA) revealed that the disease symptoms of superelongation may also result from the interactions of fungal communities in the mycobiome, including Elsinoë species and other fungi such as Colletotrichum, Cercospora, Alternaria, and Fusarium. Therefore, we suggest that examining the pathobiome concept in SED in the future is necessary. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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14 pages, 1737 KiB

Open AccessArticle

Genome-Wide Informative Microsatellite Markers and Population Structure of Fusarium virguliforme from Argentina and the USA

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Leandro Lopes da Silva

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J. Fungi 2023, 9(11), 1109; https://doi.org/10.3390/jof9111109 - 16 Nov 2023

Viewed by 348

Abstract

Soybean sudden death syndrome (SDS) is a destructive disease that causes substantial yield losses in South and North America. Whereas four Fusarium species were identified as the causal agents, F. virguliforme is the primary SDS-causing pathogen in North America and it also contributes [...] Read more.

Soybean sudden death syndrome (SDS) is a destructive disease that causes substantial yield losses in South and North America. Whereas four Fusarium species were identified as the causal agents, F. virguliforme is the primary SDS-causing pathogen in North America and it also contributes substantially to SDS in Argentina. In this study, we comparatively analyzed genome assemblies of four F. virguliforme strains and identified 29 informative microsatellite markers. Sixteen of the 29 markers were used to investigate the genetic diversity and population structure of this pathogen in a collection of 90 strains from Argentina and the USA. A total of 37 multilocus genotypes (MLGs) were identified, including 10 MLGs in Argentina and 26 in the USA. Only MLG2, the most dominant MLG, was found in both countries. Analyses with three different approaches showed that these MLGs could be grouped into three clusters. Cluster IA consisting of four MLGs exclusively from the USA has much higher genetic diversity than the other two clusters, suggesting that it may be the ancestral cluster although additional data are necessary to support this hypothesis. Clusters IB and II consisted of 13 and 21 MLGs, respectively. MLGs belonging to these two clusters were present in all four sampled states in Argentina and all five sampled states in the USA. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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11 pages, 4057 KiB

Open AccessArticle

Genetic Diversity and Population Structure of Leptosphaeria biglobosa from the Winter Oilseed Rape Region in China

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J. Fungi 2023, 9(11), 1092; https://doi.org/10.3390/jof9111092 - 09 Nov 2023

Viewed by 746

Abstract

Phoma stem canker (blackleg), caused by the fungi Leptosphaeria maculans (anamorph Phoma lingam) and L. biglobosa, is one of the most devastating diseases in oilseed rape (Brassica napus L.) production worldwide. However, the population structure and genetic variation of L. [...] Read more.

Phoma stem canker (blackleg), caused by the fungi Leptosphaeria maculans (anamorph Phoma lingam) and L. biglobosa, is one of the most devastating diseases in oilseed rape (Brassica napus L.) production worldwide. However, the population structure and genetic variation of L. biglobosa populations in China have rarely been investigated. Here, a collection of 214 fungal strains of blackleg from China (including Shaanxi, Jiangxi, Hubei, Jiangsu, Chongqing, Sichuan, Guangxi, Guizhou, Hunan, and Henan) and Europe (France and Ukraine) was identified as L. biglobosa. Three simple sequence repeat (SSR) markers were developed to characterize their population structure. The results showed that the Nei’s average gene diversity ranged from 0.6771 for the population from Jiangsu to 0.3009 for the population from Hunan. In addition, most of the genetic variability (96%) occurred within groups and there were only relatively small amounts among groups (4.0%) (F_ST = 0.043, p = 0.042 < 0.05). Pairwise population differentiation (F_ST) suggested that significant genetic differentiation was observed between different L. biglobosa populations. Bayesian and unweighted average method analysis revealed that these L. biglobosa strains were clustered into three branches, and three European strains were similar to those from eastern China. The pathogenicity assay showed that those in Group III were significantly more virulent than those in Group I (t = 2.69, p = 0.016). The study also showed that Group III was dominant in Chinese L. biglobosa populations, which provides new insights for the further study of population evolution and the management of this pathogen. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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18 pages, 3525 KiB

Open AccessArticle

Characterization of Colletotrichum Species Infecting Litchi in Hainan, China

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J. Fungi 2023, 9(11), 1042; https://doi.org/10.3390/jof9111042 - 24 Oct 2023

Viewed by 620

Abstract

Litchi (Litchi chinensis) is an evergreen fruit tree grown in subtropical and tropical countries. China accounts for 71.5% of the total litchi cultivated area in the world. Anthracnose disease caused by Colletotrichum species is one of the most important diseases of [...] Read more.

Litchi (Litchi chinensis) is an evergreen fruit tree grown in subtropical and tropical countries. China accounts for 71.5% of the total litchi cultivated area in the world. Anthracnose disease caused by Colletotrichum species is one of the most important diseases of litchi in China. In this study, the causal pathogens of litchi anthracnose in Hainan, China, were determined using phylogenetic and morphological analyses. The results identified eight Colletotrichum species from four species complexes, including a proposed new species. These were C. karsti from the C. boninense species complex; C. gigasporum and the proposed new species C. danzhouense from the C. gigasporum species complex; C. arecicola, C. fructicola species complex; C. arecicola, C. fructicola and C. siamense from the C. gloeosporioides species complex; and C. musicola and C. plurivorum from the C. orchidearum species complex. Pathogenicity tests showed that all eight species could infect litchi leaves using a wound inoculation method, although the pathogenicity was different in different species. To the best of our knowledge, the present study is the first report that identifies C. arecicola, C. danzhouense, C. gigasporum and C. musicola as etiological agents of litchi anthracnose. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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13 pages, 2011 KiB

Open AccessArticle

Cryphonectria parasitica Detections in England, Jersey, and Guernsey during 2020–2023 Reveal Newly Affected Areas and Infections by the CHV1 Mycovirus

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J. Fungi 2023, 9(10), 1036; https://doi.org/10.3390/jof9101036 - 20 Oct 2023

Viewed by 805

Abstract

In England, Cryphonectria parasitica was detected for the first time in 2011 in a nursery and in 2016 in the wider environment. Surveys between 2017 and 2020 identified the disease at different sites in Berkshire, Buckinghamshire, Cornwall, Derbyshire, Devon, Dorset, London, West Sussex, [...] Read more.

In England, Cryphonectria parasitica was detected for the first time in 2011 in a nursery and in 2016 in the wider environment. Surveys between 2017 and 2020 identified the disease at different sites in Berkshire, Buckinghamshire, Cornwall, Derbyshire, Devon, Dorset, London, West Sussex, and the island of Jersey, while the present study comprises the results of the 2020–2023 survey with findings in Derbyshire, Devon, Kent, Nottinghamshire, Herefordshire, Leicestershire, London, West Sussex, and the islands of Jersey and Guernsey. A total of 226 suspected samples were collected from 72 surveyed sites, as far north as Edinburgh and as far west as Plymouth (both of which were negative), and 112 samples tested positive by real-time PCR and isolation from 35 sites. The 112 isolates were tested for the vegetative compatibility group (VCG), mating type, and Cryphonectria hypovirus 1 (CHV1). Twelve VCGs were identified, with two of them (EU-5 and EU-22) being the first records in the UK. Both mating types were present (37% MAT-1 and 63% MAT-2), but only one mating type was present per site and VCG, and perithecia were never observed. Cryphonectria hypovirus 1 (CHV1), consistently subtype-I haplotype E-5, was detected in three isolates at a low concentration (5.9, 21.1, and 33.0 ng/µL) from locations in London, Nottinghamshire, and Devon. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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14 pages, 1814 KiB

Open AccessArticle

Genetic Diversity of Lecanosticta acicola in Pinus Ecosystems in Northern Spain

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J. Fungi 2023, 9(6), 651; https://doi.org/10.3390/jof9060651 - 09 Jun 2023

Viewed by 847

Abstract

Lecanosticta acicola is one of the most damaging species affecting Pinus radiata plantations in Spain. Favourable climatic conditions and unknown endogenous factors of the pathogen and host led to a situation of high incidence and severity of the disease in these ecosystems. With [...] Read more.

Lecanosticta acicola is one of the most damaging species affecting Pinus radiata plantations in Spain. Favourable climatic conditions and unknown endogenous factors of the pathogen and host led to a situation of high incidence and severity of the disease in these ecosystems. With the main aim of understanding the factors intrinsic to this pathogenic species, a study of the population structure in new established plantations with respect to older plantations was implemented. The genetic diversity, population structure and the ability of the pathogen to spread was determined in Northern Spain (Basque Country), where two thirds of the total Pinus radiata plantations of Spain are located. From a total of 153 Lecanosticta acicola isolates analysed, two lineages were present; the southern lineage, which was prevalent, and the northern lineage, which was scarce. A total of 22 multilocus genotypes were detected with a balanced composition of both mating types and evidence for sexual reproduction. In addition to the changing environmental conditions enhancing disease expression, the complexity and diversity of the pathogen will make it difficult to control and to maintain the wood productive system fundamentally based on this forest species. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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15 pages, 3381 KiB

Open AccessArticle

Fusarium mindanaoense sp. nov., a New Fusarium Wilt Pathogen of Cavendish Banana from the Philippines Belonging to the F. fujikuroi Species Complex

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Shunsuke Nozawa

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Yosuke Seto

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Yoshiki Takata

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Lalaine Albano Narreto

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J. Fungi 2023, 9(4), 443; https://doi.org/10.3390/jof9040443 - 05 Apr 2023

Viewed by 2615

Abstract

The pathogen causing Fusarium wilt in banana is reported to be Fusarium oxysporum f. sp. cubense (FOC). In 2019, wilt symptoms in banana plants (cultivar: Cavendish) in the Philippines were detected, i.e., the yellowing of the leaves and discoloration of the pseudostem and [...] Read more.

The pathogen causing Fusarium wilt in banana is reported to be Fusarium oxysporum f. sp. cubense (FOC). In 2019, wilt symptoms in banana plants (cultivar: Cavendish) in the Philippines were detected, i.e., the yellowing of the leaves and discoloration of the pseudostem and vascular tissue. The fungus isolated from the vascular tissue was found to be pathogenic to Cavendish bananas and was identified as a new species, F. mindanaoense, belonging to the F. fujikuroi species complex (FFSC); species classification was assessed using molecular phylogenetic analyses based on the tef1, tub2, cmdA, rpb1, and rpb2 genes and morphological analyses. A reciprocal blast search using genomic data revealed that this fungus exclusively included the Secreted in Xylem 6 (SIX6) gene among the SIX homologs related to pathogenicity; it exhibited a highly conserved amino acid sequence compared with that of species in the FFSC, but not with that of FOC. This was the first report of Fusarium wilt in Cavendish bananas caused by a species of the genus Fusarium other than those in the F. oxysporum species complex. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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11 pages, 887 KiB

Open AccessArticle

Races CYR34 and Suwon11-1 of Puccinia striiformis f. sp. tritici Played an Important Role in Causing the Stripe Rust Epidemic in Winter Wheat in Yili, Xinjiang, China

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J. Fungi 2023, 9(4), 436; https://doi.org/10.3390/jof9040436 - 03 Apr 2023

Cited by 2 | Viewed by 1463

Abstract

Wheat stripe rust caused by Puccinia striiformis f. sp. tritici is a destructive disease. Its pathogen frequently adapts to newly invaded regions and overcomes resistance in wheat cultivars. This disease is especially important in China due to its favorable conditions for the stripe [...] Read more.

Wheat stripe rust caused by Puccinia striiformis f. sp. tritici is a destructive disease. Its pathogen frequently adapts to newly invaded regions and overcomes resistance in wheat cultivars. This disease is especially important in China due to its favorable conditions for the stripe rust epidemic and the recombination population structure of pathogens. Xinjiang is a vast epidemic region in China, but very limited research on this disease has been performed in this region. In this study, we identified 25 races from 129 isolates collected from winter wheat fields from five different regions (Nileke, Xinyuan, Gongliu, Huocheng, and Qapqal) of Yili, Xinjiang, using the Chinese set of 19 differential wheat lines. All isolates were virulent on the differentials Fulhad and Early Premium, but no isolates were virulent on Yr5. Among the 25 races, Suwon11-1 was the most prevalent, followed by CYR34. Both races were found in four out of the five locations. It is important to continue monitoring stripe rust and its pathogen races in this region, as it forms a pathway between China and Central Asia. Collaborative research is essential for controlling stripe rust in this region, other regions in China, and neighboring countries. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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11 pages, 1891 KiB

Open AccessArticle

First Report on Colletotrichum fructicola Causing Anthracnose in Chinese Sorghum and Its Management Using Phytochemicals

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J. Fungi 2023, 9(2), 279; https://doi.org/10.3390/jof9020279 - 20 Feb 2023

Cited by 2 | Viewed by 1345

Abstract

Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We [...] Read more.

Sorghum bicolor is cultivated worldwide. Leaf spots on sorghum, which lead to leaf lesions and impaired growth, are prevalent and severe in Guizhou Province, Southwest China. In August 2021, new leaf spot symptoms were observed on sorghum plants growing in agricultural fields. We used conventional tissue isolation methods and pathogenicity determination tests. Inoculations of sorghum with isolate 022ZW resulted in brown lesions similar to those observed under field conditions. The original inoculated isolates were reisolated and fulfilled Koch’s postulates. Based on the morphological character and phylogenetic analyses of the combined sequences of the internal transcribed spacer (ITS) region and the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes, we identified the isolated fungus as C. fructicola. This paper is the first to report this fungus-causing disease in sorghum leaves. We studied the sensitivity of the pathogen to various phytochemicals. The sensitivity of C. fructicola to seven phytochemicals was measured using the mycelial growth rate method. Honokiol, magnolol, thymol, and carvacrol displayed good antifungal effects, with EC₅₀ (concentration for 50% of the maximal effect) values of 21.70 ± 0.81, 24.19 ± 0.49, 31.97 ± 0.51, and 31.04 ± 0.891 µg/mL, respectively. We tested the control effect of the seven phytochemicals on the anthracnose caused by C. fructicola: honokiol and magnolol displayed good field efficacy. In this study, we expand the host range of C. fructicola, providing a basis for controlling sorghum leaf diseases caused by C. fructicola. Full article

(This article belongs to the Special Issue Fungal Plant Pathogens)

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