Phaeoacremonium: From esca disease to phaeohyphomycosis

Trichoderma spp. are well-known biological agents that have significant antagonistic activity against several plant pathogenic fungi. In the present study, Trichoderma spp. were tested in vitro for...

Antagonistic assessment of Trichoderma spp. by producing volatile and non-volatile compounds against different fungal pathogens

This study is unique as it compares traditional and high-resolution culture-independent approaches using the same set of samples to study the saprotrophic fungi on Vitis vinifera. We identified the saprotrophic communities of table grape (Red Globe) and wine grape (Carbanate Gernischet) in China using both traditional and culture-independent techniques. The traditional approach used direct observations based on morphology, single spore isolation and phylogenetic analysis yielding 45 taxa which 19 were commonly detected in both cultivars. The same set of samples were then used for Illumina sequencing which analyzed ITS1 sequence data and detected 226 fungal OTUs, of which 176 and 189 belong to the cultivars Carbanate Gernischet and Red Globe, respectively. There were 139 OTUs shared between the two V. vinifera cultivars and 37 and 50 OTUs were specific to Carbanate Gernischet and Red Globe cultivars respectively. In the Carbanate Gernischet cultivar, Ascomycota accounted for 77% of the OTUs and in Red Globe, almost all sequenced were Ascomycota. The fungal taxa overlap at the genus and species level between the traditional and culture-independent approach was relatively low. In the traditional approach we were able to identify the taxa to species level, while in the culture-independent method we were frequently able to identify the taxa to family or genus level. This is remarkable as we used the same set of samples collected in China for both approaches. We recommend the use of traditional techniques to accurately identify taxa. Culture-independent method can be used to get a better understanding about the organisms that are present in a host in its natural environment. We identified primary and secondary plant pathogens and endophytes in the saprotrophic fungal communities, which support previous observations, that dead plant material in grape vineyards can be the primary sources of disease. Finally, based on present and previous findings, we provide a worldwide checklist of 905 fungal taxa on Vitis species, which includes their mode of life and distribution.

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Biodiversity of fungi on Vitis vinifera L. revealed by traditional and high-resolution culture-independent approaches

The cosmopolitan plant genus Clematis contains many climbing species that can be found worldwide. The genus occurs in the wild and is grown commercially for horticulture. Microfungi on Clematis were collected from Belgium, China, Italy, Thailand and the UK. They are characterized by morphology and analyses of gene sequence data using an integrated species concept to validate identifications. The study revealed two new families, 12 new genera, 50 new species, 26 new host records with one dimorphic character report, and ten species are transferred to other genera. The new families revealed by multigene phylogeny are Longiostiolaceae and Pseudomassarinaceae in Pleosporales (Dothideomycetes). New genera are Anthodidymella (Didymellaceae), Anthosulcatispora and Parasulcatispora (Sulcatisporaceae), Fusiformispora (Amniculicolaceae), Longispora (Phaeosphaeriaceae), Neobyssosphaeria (Melanommataceae), Neoleptosporella (Chaetosphaeriales, genera incertae sedis), Neostictis (Stictidaceae), Pseudohelminthosporium (Neomassarinaceae), Pseudomassarina (Pseudomassarinaceae), Sclerenchymomyces (Leptosphaeriaceae) and Xenoplectosphaerella (Plectosphaerellaceae). The newly described species are Alloleptosphaeria clematidis, Anthodidymella ranunculacearum, Anthosulcatispora subglobosa, Aquadictyospora clematidis, Brunneofusispora clematidis, Chaetosphaeronema clematidicola, C. clematidis, Chromolaenicola clematidis, Diaporthe clematidina, Dictyocheirospora clematidis, Distoseptispora clematidis, Floricola clematidis, Fusiformispora clematidis, Hermatomyces clematidis, Leptospora clematidis, Longispora clematidis, Massariosphaeria clematidis, Melomastia clematidis, M. fulvicomae, Neobyssosphaeria clematidis, Neoleptosporella clematidis, Neoroussoella clematidis, N. fulvicomae, Neostictis nigricans, Neovaginatispora clematidis, Parasulcatispora clematidis, Parathyridaria clematidis, P. serratifoliae, P. virginianae, Periconia verrucose, Phomatospora uniseriata, Pleopunctum clematidis, Pseudocapulatispora clematidis, Pseudocoleophoma clematidis, Pseudohelminthosporium clematidis, Pseudolophiostoma chiangraiense, P. clematidis, Pseudomassarina clematidis, Ramusculicola clematidis, Sarocladium clematidis, Sclerenchymomyces clematidis, Sigarispora clematidicola, S. clematidis, S. montanae, Sordaria clematidis, Stemphylium clematidis, Wojnowiciella clematidis, Xenodidymella clematidis, Xenomassariosphaeria clematidis and Xenoplectosphaerella clematidis. The following fungi are recorded on Clematis species for the first time: Angustimassarina rosarum, Dendryphion europaeum, Dermatiopleospora mariae, Diaporthe ravennica, D. rudis, Dichotomopilus ramosissimum, Dictyocheirospora xishuangbannaensis, Didymosphaeria rubi-ulmifolii, Fitzroyomyces cyperacearum, Fusarium celtidicola, Leptospora thailandica, Memnoniella oblongispora, Neodidymelliopsis longicolla, Neoeutypella baoshanensis, Neoroussoella heveae, Nigrograna chromolaenae, N. obliqua, Pestalotiopsis verruculosa, Pseudoberkleasmium chiangmaiense, Pseudoophiobolus rosae, Pseudoroussoella chromolaenae, P. elaeicola, Ramusculicola thailandica, Stemphylium vesicarium and Torula chromolaenae. The new combinations are Anthodidymella clematidis (≡ Didymella clematidis), A. vitalbina (≡ Didymella vitalbina), Anthosulcatispora brunnea (≡ Neobambusicola brunnea), Fuscohypha kunmingensis (≡ Plectosphaerella kunmingensis), Magnibotryascoma rubriostiolata (≡ Teichospora rubriostiolata), Pararoussoella mangrovei (≡ Roussoella mangrovei), Pseudoneoconiothyrium euonymi (≡ Roussoella euonymi), Sclerenchymomyces jonesii (≡ Neoleptosphaeria jonesii), Stemphylium rosae (≡ Pleospora rosae), and S. rosae-caninae (≡ Pleospora rosae-caninae). The microfungi on Clematis is distributed in several classes of Ascomycota. The analyses are based on morphological examination of specimens, coupled with phylogenetic sequence data. To the best of our knowledge, the consolidated species concept approach is recommended in validating species.

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Microfungi associated with Clematis (Ranunculaceae) with an integrated approach to delimiting species boundaries

The taxonomy of the genus Colletotrichum has undergone tremendous changes over the last decade, with over 200 species being currently recognised and species complexes being informally used to cluster those species. Many of these species are important plant pathogens, some rather polyphagous and others host-specific, but several occur seldomly and some may in fact be ecologically endangered. Based mainly on literature from the past decade, in this work we review the occurrence, geographic distribution and host spectrum of currently recognised Colletotrichum species under phylogenetic, pathological/agronomic and ecological perspectives, providing a list arranged by Colletotrichum species and species complexes. A total of 257 species are listed and grouped into 15 species complexes. In this work we have recorded 1353 unique host species-Colletotrichum species association records from 720 hosts, with the Fabaceae as the family with higher number of hosts (52 host species) but with the Rosaceae as the family with the highest number of host species-Colletotrichum species association records (118 association records). According to occurrence data, 88 species are common in nature, 128 were considered as data deficient and 41 are threatened, some of which are likely extinct from nature and preserved only in culture collections. Several species are relevant plant pathogens, in some cases geographically confined and thus of potential quarantine relevance. Based on the major changes that occurred on Colletotrichum taxonomy over the last decade, this work provides a comprehensive overview of occurrence data of Colletotrichum species, compiling host range and geographical distribution, with relevance for plant pathology and conservation mycology. The current taxonomic framework in Colletotrichum is revealing numerous species but poses challenges to the employment of standard criteria for the evaluation of biological conservation of these fungi. We advocate that conservation mycology and taxonomy should find common routes simultaneously enabling the correct delimitation of species of Colletotrichum and the implementation of feasible criteria for the evaluation of conservation. The employment of new technologies, such whole genome sequencing (WGS), will help and support the description of new species and to gain a better understanding of the genetic bases of speciation processes.

Colletotrichum species and complexes: geographic distribution, host range and conservation status

In recent years, grapevine trunk diseases have gained growing attentions due to worldwide incidence of the disease. In a survey on fungal agents associated with grapevine trunk diseases in northern Iran, wood samples were collected from grapevines having the symptoms of declination. Isolation was made using routine plant pathology methods. A coelomycetous fungus with appendage-bearing conidia was recovered from symptomatic tissues. Based on morphological and cultural characteristics, the causal agent of the disease was identified as Truncatella angustata. The identity of the species was further confirmed by sequence data of internal transcribed spacer-rDNA region. A phylogeny inferred using sequence data obtained in this study, together with the sequences from GenBank, clustered our isolates together with T. angustata known from other host plant species. Pathogenicity tests performed on detached shoots of grapevines led to the same symptoms as observed in field conditions. This is first study on the pathogenicity of T. angustata on grapevine in Iran and first report on the occurrence of T. angustata on grapevine in Iran.

Truncatella angustata associated with grapevine trunk disease in northern Iran

Phaeoacremonium spp. are known as the main Hyphomycetes associated with esca disease symptoms on grapevines worldwide. The role of other woody hosts in proximity of vineyards as a possible inoculum source for the causal agents of grapevine esca disease mainly remains unknown. The aim of this study was to investigate the occurrence of Phaeoacremonium spp. on pome and stone fruit with trunk diseases symptoms in northwestern parts of Iran. For this purpose, wood trees samples were collected from apple and apricot trees with trunk disease symptoms. Isolation was made using routine plant pathology methods. Based on the morphological and cultural characteristics, Phaeoacremonium aleophilum and Phaeoacremonium iranianum were identified from apple trees and P. aleophilum was recovered from apricot trees with trunk disease symptoms. A phylogenetic analysis based on the sequence data from β-tubulin gene further confirmed the identity of the species as P. aleophilum and P. iranianum. The results of inoculation assay...

Pome and stone fruit trees as possible reservoir hosts for Phaeoacremonium spp., the causal agents of grapevine esca disease, in Iran

Sunflower leaf spot is one of the most common as well as important foliar diseases of this host in northern Iran. Stemphylium vesicarium was revealed to be one of the causal agents of sunflower leaf spot based on morphological and molecular characteristics. The identity of the species was confirmed using sequence data from the ITS rDNA region and glyceraldehyde-3-phosphate dehydrogenase (gpd) gene sequences. Pathogenicity of the fungus was proven by inoculation of four-week-old sunflower plants (cv. Euroflor) under controlled conditions. This is the first report on the incidence of S. vesicarium on H. annuus anywhere in the world.

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Helianthus annuus as a natural host for Stemphylium vesicarium in Iran

Leaf spot disease of sunflower is one of the most important foliar diseases on this crop worldwide. Several fungal groups are known to cause leaf spot disease on sunflower. Species of the genus Alternaria are the most common and serious leaf spot causing fungi on this crop. Leaf spot disease is the most destructive foliar diseases on sunflower in northern Iran; however, the identity of the causal agent remains unknown. The present study was aimed to characterise the identity of the causal agent of the disease by means of morphological and molecular data as well as to evaluate the pathogenicity of the responsible species. For this purpose, a total number of 97 fungal isolates were recovered from sunflower leaves with leaf spot disease symptoms from the sunflower fields in northwestern zone of Iran. All of the isolates were identified as Alternaria alternata based on cultural and morphological characteristics. A subset of isolates was subjected to phylogenetic analysis using sequence data from ITS-rDNA regi...

Morphology, phylogeny and pathogenicity of Alternaria species, involved in leaf spot disease of sunflower in northern Iran

Polygonatum odoratum (Mill.) Druce (Angular Solomon's seal) is a well-known ornamental plant and herbal drug, which is used in traditional medicine. Severe leaf spots were observed in wild Angular Solomon's seal plants in a public park in Trento, Italy. A combination of morphological and molecular characteristics, including sequence data of ITS-rDNA, large subunit (LSU), beta tubulin (TUB) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) led to identification of two species, namely Phoma odoratissimi and Colletotrichum dematium s. str., isolated from these leaf spots. Pathogenicity of the isolates was confirmed on wounded leaves of Po. odoratum; indeed, both species induced leaf spot symptoms on inoculated leaves within 10 days of inoculation. This is the first report of leaf spot disease caused by Ph. odoratissimi and C. dematium s. str. on Po. odoratum, which can be considered a new host for both the species examined in this study. In addition, isolation of Ph. odoratissimi represents a new record for the mycobiota of Italy.

Sima Khodaei

Papers

Truncatella angustata associated with grapevine trunk disease in northern Iran

Pome and stone fruit trees as possible reservoir hosts for Phaeoacremonium spp., the causal agents of grapevine esca disease, in Iran

Helianthus annuus as a natural host for Stemphylium vesicarium in Iran

Morphology, phylogeny and pathogenicity of Alternaria species, involved in leaf spot disease of sunflower in northern Iran

Identification and characterization of two new fungal pathogens of Polygonatum odoratum (Angular Solomon's seal) in Italy