Fusarium bilaiae, a new cryptic species in the Fusarium fujikuroi complex associated with sunflower

A Fusarium species associated with sunflower based on multilocus genealogy, morphological, physiological, ecological, mating type, and mycotoxin production data is formally described as the newly discovered species Fusarium bilaiae. The F. bilaiae strains formed a genealogically exclusive lineage within the African clade of the F. fujikuroi species complex. Comparison of morphological characteristics of F. bilaiae strains with those of the closely related F. phyllophilum strain NRRL 13617 revealed similarities in the main micromorphology of both species: production of numerous one-celled microconidia in false heads and short chains on monophialides and polyphialides and the absence of macroconidia and sporodochia. There was a slight but significant distinction between the two species when the strains were grown on different agar media, as well as in the shape and width of microconidia. Fusarium bilaiae strains isolated from symptomatic sunflower were not pathogenic to members of the Asteraceae tested; apparently, they live as saprophytes or endophytes in sunflower tissues. A difference between the strains of the two species in the production of mycotoxins was demonstrated with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. On autoclaved rice, F. bilaiae did not produce fumonisins and beauvericin but produced moniliformin, whereas F. phyllophilum produced all these mycotoxins. A polymerase chain reaction (PCR) assay specific for mating type alleles identified F. bilaiae as a putative heterothallic species with MAT1-1 and MAT1-2 idiomorphs, but laboratory crosses were unsuccessful. Determining the area and host range of the new endophytic species F. bilaiae is a priority for future research.

Identification and Laboratory Fungicides Screening of the Pathogenic Fungus of Stem Spot of Pitaya (Hylocereus spp.) Stems

In this study, the pathogenic fungus of stem spot disease of pitaya (Hylocereus spp.) stems was identified by isolation and purification, pathogenicity test, morphological characteristics, and analysis of rDNA-ITS sequences. The results turned out that the rDNA-ITS sequences of the H1 strain showed 100% of identity with Botryosphaeria dothidea, indicating that the pathogenic fungus of stem spot disease of pitaya stems was Botryosphaeria dothidea. Meanwhile, the H1 strain was then used as a reference strain to screen some commercial fungicides. The bioassay test results indicated that prochloraz had an obvious inhibitory effect on Botryosphaeria dothidea with the EC50 value of 0.0798 μg/mL. Our study could provide a theoretical basis for the effective control method of stem spot disease of pitaya.

Fusarium chaquense, sp. nov, a novel type A trichothecene-producing species from native grasses in a wetland ecosystem in Argentina

The Chaco wetland is among the most biologically diverse regions in Argentina. In collections of fungi from asymptomatic native grasses (Poaceae) from the wetlands, we identified isolates of Fusarium that were morphologically similar to F. armeniacum, but distinct from it by their production of abundant microconidia. All the isolates had identical, or nearly identical, partial sequences of TEF1 and RPB2. But they were distinct from reference sequences from F. armeniacum and Fusarium species closely related to it. Phylogenetic analysis of 34 full-length housekeeping gene sequences retrieved from whole genome sequences of three Chaco wetland isolates, 29 genes resolved the isolates as an exclusive clade within the F. sambucinum species complex. Based on results of the morphological and phylogenetic analysis, we concluded that the Chaco wetland isolates are a distinct and novel species, herein described as Fusarium chaquense, sp. nov., which is closely related to F. armeniacum. F. chaquense in culture can produce the trichothecenes T-2 and HT-2 toxin, neosolaniol, diacetoxyscirpenol, and monoacetoxyscirpenol, as well as beauvericin and the pigment aurofusarin. Genome sequence analysis also revealed the presence of three previously described loci required for trichothecene biosynthesis. This research represents the first study of Fusarium in a natural ecosystem in Argentina.

Fungal quinones: diversity, producers, and applications of quinones from Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium

Quinones represent an important group of highly structurally diverse, mainly polyketide-derived secondary metabolites widely distributed among filamentous fungi. Many quinones have been reported to have important biological functions such as inhibition of bacteria or repression of the immune response in insects. Other quinones, such as ubiquinones are known to be essential molecules in cellular respiration, and many quinones are known to protect their producing organisms from exposure to sunlight. Most recently, quinones have also attracted a lot of industrial interest since their electron-donating and -accepting properties make them good candidates as electrolytes in redox flow batteries, like their often highly conjugated double bond systems make them attractive as pigments. On an industrial level, quinones are mainly synthesized from raw components in coal tar. However, the possibility of producing quinones by fungal cultivation has great prospects since fungi can often be grown in industrially scaled bioreactors, producing valuable metabolites on cheap substrates. In order to give a better overview of the secondary metabolite quinones produced by and shared between various fungi, mainly belonging to the genera Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium, this review categorizes quinones into families such as emodins, fumigatins, sorbicillinoids, yanuthones, and xanthomegnins, depending on structural similarities and information about the biosynthetic pathway from which they are derived, whenever applicable. The production of these quinone families is compared between the different genera, based on recently revised taxonomy. KEY POINTS: • Quinones represent an important group of secondary metabolites widely distributed in important fungal genera such as Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium. • Quinones are of industrial interest and can be used in pharmacology, as colorants and pigments, and as electrolytes in redox flow batteries. • Quinones are grouped into families and compared between genera according to the revised taxonomy.

How to publish a new fungal species, or name, version 3.0

It is now a decade since The International Commission on the Taxonomy of Fungi (ICTF) produced an overview of requirements and best practices for describing a new fungal species. In the meantime the International Code of Nomenclature for algae, fungi, and plants (ICNafp) has changed from its former name (the International Code of Botanical Nomenclature) and introduced new formal requirements for valid publication of species scientific names, including the separation of provisions specific to Fungi and organisms treated as fungi in a new Chapter F. Equally transformative have been changes in the data collection, data dissemination, and analytical tools available to mycologists. This paper provides an updated and expanded discussion of current publication requirements along with best practices for the description of new fungal species and publication of new names and for improving accessibility of their associated metadata that have developed over the last 10 years. Additionally, we provide: (1) model papers for different fungal groups and circumstances; (2) a checklist to simplify meeting (i) the requirements of the ICNafp to ensure the effective, valid and legitimate publication of names of new taxa, and (ii) minimally accepted standards for description; and, (3) templates for preparing standardized species descriptions.

Fusarium: more than a node or a foot-shaped basal cell

Recent publications have argued that there are potentially serious consequences for researchers in recognising distinct genera in the terminal fusarioid clade of the family Nectriaceae. Thus, an alternate hypothesis, namely a very broad concept of the genus Fusarium was proposed. In doing so, however, a significant body of data that supports distinct genera in Nectriaceae based on morphology, biology, and phylogeny is disregarded. A DNA phylogeny based on 19 orthologous protein-coding genes was presented to support a very broad concept of Fusarium at the F1 node in Nectriaceae. Here, we demonstrate that re-analyses of this dataset show that all 19 genes support the F3 node that represents Fusarium sensu stricto as defined by F. sambucinum (sexual morph synonym Gibberella pulicaris). The backbone of the phylogeny is resolved by the concatenated alignment, but only six of the 19 genes fully support the F1 node, representing the broad circumscription of Fusarium. Furthermore, a re-analysis of the concatenated dataset revealed alternate topologies in different phylogenetic algorithms, highlighting the deep divergence and unresolved placement of various Nectriaceae lineages proposed as members of Fusarium. Species of Fusarium s. str. are characterised by Gibberella sexual morphs, asexual morphs with thin- or thick-walled macroconidia that have variously shaped apical and basal cells, and trichothecene mycotoxin production, which separates them from other fusarioid genera. Here we show that the Wollenweber concept of Fusarium presently accounts for 20 segregate genera with clear-cut synapomorphic traits, and that fusarioid macroconidia represent a character that has been gained or lost multiple times throughout Nectriaceae. Thus, the very broad circumscription of Fusarium is blurry and without apparent synapomorphies, and does not include all genera with fusarium-like macroconidia, which are spread throughout Nectriaceae (e.g., Cosmosporella, Macroconia, Microcera). In this study four new genera are introduced, along with 18 new species and 16 new combinations. These names convey information about relationships, morphology, and ecological preference that would otherwise be lost in a broader definition of Fusarium. To assist users to correctly identify fusarioid genera and species, we introduce a new online identification database, Fusarioid-ID, accessible at www.fusarium.org. The database comprises partial sequences from multiple genes commonly used to identify fusarioid taxa (act1, CaM, his3, rpb1, rpb2, tef1, tub2, ITS, and LSU). In this paper, we also present a nomenclator of names that have been introduced in Fusarium up to January 2021 as well as their current status, types, and diagnostic DNA barcode data. In this study, researchers from 46 countries, representing taxonomists, plant pathologists, medical mycologists, quarantine officials, regulatory agencies, and students, strongly support the application and use of a more precisely delimited Fusarium (= Gibberella) concept to accommodate taxa from the robust monophyletic node F3 on the basis of a well-defined and unique combination of morphological and biochemical features. This F3 node includes, among others, species of the F. fujikuroi, F. incarnatum-equiseti, F. oxysporum, and F. sambucinum species complexes, but not species of Bisifusarium [F. dimerum species complex (SC)], Cyanonectria (F. buxicola SC), Geejayessia (F. staphyleae SC), Neocosmospora (F. solani SC) or Rectifusarium (F. ventricosum SC). The present study represents the first step to generating a new online monograph of Fusarium and allied fusarioid genera (www.fusarium.org).

Size-exclusion chromatography allows the isolation of EVs from the filamentous fungal plant pathogen Fusarium oxysporum f. sp. vasinfectum (Fov)

Extracellular vesicles (EVs) are nano-sized compartments involved in cell communication and macromolecule transport that are well characterized in mammalian organisms. Fungal EVs transport virulence-related cargo and modulate the host immune response, but most work has been focused on human yeast pathogens. Additionally, the study of EVs from filamentous fungi has been hindered by the lack of protein markers and efficient isolation methods. In this study we performed the isolation and proteomic characterization of EVs from the filamentous cotton pathogen Fusarium oxysporum f. sp. vasinfectum (Fov). EVs were recovered from two different growth media, Czapek Dox and Saboraud's dextrose broth, and purified by size-exclusion chromatography. Our results show that the EV proteome changes depending on the growth medium but EV production remains constant. EVs contained proteins involved in polyketide synthesis, cell wall modifications, proteases and potential effectors. These results support a role in modulation of host-pathogen interactions for Fov EVs.

Divergence and Gene Flow Between Fusarium subglutinans and F. temperatum Isolated from Maize in Argentina

Fusarium subglutinans and F. temperatum are two important fungal pathogens of maize whose distinctness as separate species has been difficult to assess. We isolated strains of these species from commercial and native maize varieties in Argentina and sequenced >28,000 loci to estimate genetic variation in the sample. Our objectives were to measure genetic divergence between the species, infer demographic parameters related to their split, and describe the population structure of the sample. When analyzed together, over 30% of each species' polymorphic sites (>2,500 sites) segregate as polymorphisms in the other. Demographic modeling confirmed the species split predated maize domestication, but subsequent between-species gene flow has occurred, with gene flow from F. subglutinans into F. temperatum greater than gene flow in the reverse direction. In F. subglutinans, little evidence exists for substructure or recent selective sweeps, but there is evidence for limited sexual reproduction. In F. temperatum, there is clear evidence for population substructure and signals of abundant recent selective sweeps, with sexual reproduction probably less common than in F. subglutinans. Both genetic variation and the relative number of polymorphisms shared between species increase near the telomeres of all 12 chromosomes, where genes related to plant-pathogen interactions often are located. Our results suggest that species boundaries between closely related Fusarium species can be semipermeable and merit further study. Such semipermeability could facilitate unanticipated genetic exchange between species and enable quicker permanent responses to changes in the agro-ecosystem, e.g., pathogen-resistant host varieties, new chemical and biological control agents, and agronomic practices.

Natural blue pigments and bikaverin

In last years, the main studied microbial sources of natural blue pigments have been the eukaryotic algae, Rhodophytes and Cryptophytes, and the cyanobacterium Arthrospira (Spirulina) platensis, responsible for the production of phycocyanin, one of the most important blue compounds approved for food and cosmetic use. Recent research also includes the indigoidine pigment from the bacteria Erwinia, Streptomyces and Photorhabdus. Despite these advances, there are still few options of microbial blue pigments reported so far, but the interest in these products is high due to the lack of stable natural blue pigments in nature. Filamentous fungi are particularly attractive for their ability to produce pigments with a wide range of colors. Bikaverin is a red metabolite present mainly in species of the genus Fusarium. Although originally red, the biomass containing bikaverin changes its color to blue after heat treatment, through a mechanism still unknown. In addition to the special behavior of color change by thermal treatment, bikaverin has beneficial biological properties, such as antimicrobial and antiproliferative activities, which can expand its use for the pharmaceutical and medical sectors. The present review addresses the production natural blue pigments and focuses on the properties of bikaverin, which can be an important source of blue pigment with potential applications in the food industry and in other industrial sectors.

In Vitro Antagonistic Activity of Trichoderma harzianum against Fusarium sudanense Causing Seedling Blight and Seed Rot on Wheat

Fusarium sudanense is a novel fungus recently isolated from asymptomatic samples of wheat grains in Argentina. The fungus caused symptoms of seedling blight and seed rot on wheat after artificial inoculations. It is known that the production of mycotoxins by pathogens belonging to the Fusarium genus is harmful to human and animal health. Moreover, the warm and humid conditions that are favorable for growth and mycotoxin production of these species put the Argentinian wheat production area at a high risk of mycotoxin contamination with this novel pathogen. The aim of this work was to evaluate the antagonistic effect of Trichoderma harzianum against F. sudanense under in vitro tests at different environmental conditions. Fungi were screened in dual culture at different water activities (α_w) (0.995, 0.98, 0.95, and 0.90) and temperatures (25 and 15 °C). The growth rate of the fungi, interaction types, and dominance index were evaluated. Also, the interaction between T. harzianum and F. sudanense was examined by light and cryo-scanning microscopy. T. harzianum suppressed the growth of F. sudanense at 0.995, 0.98, and 0.95 α_w at 25 °C and 0.995 and 0.98 α_w at 15 °C. Macroscopic study revealed different interaction types between F. sudanense and T. harzianum on dual culture. Dominance on contact where the colonies of T. harzianum overgrew the pathogen was the most common interaction type determined. The competitive capacity of T. harzianum was diminished by decreasing the temperature and α_w. At 0.95 α_w and 15 °C, both fungi grew slowly, and interaction type "A" was assigned. Microscopic analysis from the interaction zone of dual cultures revealed an attachment of T. harzianum to the F. sudanense hyphae, penetration with or without formation of appressorium-like structures, coiling, plasmolysis, and a veil formation. According to our results, T. harzianum demonstrated capability to antagonize F. sudanense and could be a promising biocontrol agent.

Fusarium volatile, a new potential pathogen from a human respiratory sample

We describe the isolation and characterization of Fusarium volatile from a bronchoalveolar lavage (BAL) sample of a female patient living in French Guiana with underlying pulmonary infections. Phylogenetic analysis of fragments of the calmodulin (cmdA), translation elongation factor (tef1), RNA polymerase second largest subunit (rpb2), and β-tubulin (tub) loci revealed that strain CBS 143874 was closely related to isolate NRRL 25615, a known but undescribed phylogenetic species belonging to the African clade of the Fusarium fujikuroi species complex. The fungus differed phylogenetically and morphologically from related known species, and is therefore described as the new taxon Fusarium volatile. Antifungal susceptibility testing suggested that the new species is resistant to echinocandins, fluconazole, itraconazole with lower MICs against amphotericin B, voriconazole and posaconazole.

A loop-mediated isothermal amplification (LAMP) based assay for the rapid and sensitive group-specific detection of fumonisin producing Fusarium spp

Fumonisins are mycotoxins that contaminate maize and maize-based food products, and feed. They have been associated with nerve system disorders in horses, pulmonary edema in swine as well as neural tube defects and esophageal cancer in humans. The fum1 gene codes for a polyketide synthase involved in the biosynthesis of fumonisins. It is present in the genomes of all fumonisin producing Fusarium spp. Reliable detection of fum1 can provide an estimate of the toxicological potential of cultures and food sources. Therefore, a fum1 specific LAMP assay was developed and tested with purified DNA of 48 different species from the Fusarium fujikuroi species complex (FFSC). The fum1 gene was detected in 22 species among which F. fujikuroi, F. globosum, F. nygamai, F. proliferatum, F. subglutinans and F. verticillioides were the most prominent fumonisin producers. None out of 92 tested non-Fusarium species showed cross reactions with the new assay. The lowest limit of detection (LOD) was 5 pg of genomic DNA per reaction for F. fujikuroi, F. nygamai and F. verticillioides. Higher LODs were found for other LAMP positive species. Apart from pure genomic DNA, the LAMP assay detected fumonisin-producers when 10³ conidia/reaction were used as template after mechanical lysis. LAMP-results were well correlated with FB1 production. This is the first report on fumonisin production in strains of F. annanatum, F. coicis, F. mundagurra, F. newnesense, F. pininemorale, F. sororula, F. tjataeba, F. udum and F. werrikimbe. Usefulness of the LAMP assay was demonstrated by analyzing fumonisin contaminated maize grains. The new LAMP assay is rapid, sensitive and reliable for the diagnosis of typical fumonisin producers and can be a versatile tool in HACCP concepts that target the reduction of fumonisins in the food and feed chain.

Resolving Fusarium: Current Status of the Genus

The fungal genus Fusarium is one of the most important groups of plant-pathogenic fungi and affects a huge diversity of crops in all climatic zones across the globe. In addition, it is also a human pathogen and produces several extremely important mycotoxins in food products that have deleterious effects on livestock and humans. These fungi have been plagued over the past century by different perspectives of what constitutes the genus Fusarium and how many species occur within the genus. Currently, there are conflicting views on the generic boundaries and what defines a species that impact disease diagnosis, management, and biosecurity legislation. An approach to defining and identifying Fusarium that places the needs of the community of users (especially, in this case, phytopathologists) to the forefront is presented in this review.

Variation in secondary metabolite production potential in the Fusarium incarnatum-equiseti species complex revealed by comparative analysis of 13 genomes

Background

The Fusarium incarnatum-equiseti species complex (FIESC) comprises 33 phylogenetically distinct species that have been recovered from diverse biological sources, but have been most often isolated from agricultural plants and soils. Collectively, members of FIESC can produce diverse mycotoxins. However, because the species diversity of FIESC has been recognized only recently, the potential of species to cause mycotoxin contamination of crop plants is unclear. In this study, therefore, we used comparative genomics to investigate the distribution of and variation in genes and gene clusters responsible for the synthesis of mycotoxins and other secondary metabolites (SMs) in FIESC.

Results

We examined genomes of 13 members of FIESC that were selected based primarily on their phylogenetic diversity and/or occurrence on crops. The presence and absence of SM biosynthetic gene clusters varied markedly among the genomes. For example, the trichothecene mycotoxin as well as the carotenoid and fusarubin pigment clusters were present in all genomes examined, whereas the enniatin, fusarin, and zearalenone mycotoxin clusters were present in only some genomes. Some clusters exhibited discontinuous patterns of distribution in that their presence and absence was not correlated with the phylogenetic relationships of species. We also found evidence that cluster loss and horizontal gene transfer have contributed to such distribution patterns. For example, a combination of multiple phylogenetic analyses suggest that five NRPS and seven PKS genes were introduced into FIESC from other Fusarium lineages.

Conclusion

Our results suggest that although the portion of the genome devoted to SM biosynthesis has remained similar during the evolutionary diversification of FIESC, the ability to produce SMs could be affected by the different distribution of related functional and complete gene clusters.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5567-7) contains supplementary material, which is available to authorized users.

Molecular systematics of two sister clades, the Fusarium concolor and F. babinda species complexes, and the discovery of a novel microcycle macroconidium-producing species from South Africa

Multilocus DNA sequence data were used to investigate species identity and diversity in two sister clades, the Fusarium concolor (FCOSC) and F. babinda species complexes. Of the 109 isolates analyzed, only 4 were received correctly identified to species and these included 1/46 F. concolor, 1/31 F. babinda, and 2/3 F. anguioides. The majority of the F. concolor and F. babinda isolates were received as F. polyphialidicum, which is a heterotypic synonym of the former species. Previously documented from South America, Africa, Europe, and Australia, our data show that F. concolor is also present in North America. The present study expands the known distribution of F. babinda in Australia to Asia, Europe, and North America. The molecular phylogenetic results support the recognition of a novel Fusarium species within the FCOSC, which is described and illustrated here as F. austroafricanum, sp. nov. It was isolated as an endophyte of kikuyu grass associated with a putative mycotoxicosis of cattle and from plant debris in soil in South Africa. Fusarium austroafricanum is most similar morphologically to F. concolor and F. babinda but differs from the latter two species in producing (i) much longer macroconidia in which the apical cell is blunt to slightly papillate and the basal cell is only slightly notched and (ii) macroconidia via microcycle conidiation on water agar. BLASTn searches of the whole genome sequence of F. austroafricanum NRRL 53441 were conducted to predict mycotoxin potential, using genes known to be essential for the synthesis of several mycotoxins and biologically active metabolites. Based on the presence of intact gene clusters that confer the ability to synthesize mycotoxins and pigments, we analyzed cracked corn kernel cultures of F. austroafricanum via liquid chromatography-mass spectrometry (LC-MS) but failed to detect these metabolites in vitro.

Fusarium subtropicale, sp. nov., a novel nivalenol mycotoxin-producing species isolated from barley (Hordeum vulgare) in Brazil and sister to F. praegraminearum

Surveys were conducted in commercial wheat and barley fields in the south central production regions of state of Paraná, Brazil, from 2011 to 2015. Spikes displaying visible Fusarium head blight symptoms were collected and the pathogen isolated from the tissues. The 754 Fusarium isolates recovered were identified by a high-throughput multilocus genotyping assay (MLGT) designed to identify trichothecene toxin-producing fusaria (i.e., formerly B-clade, but referred to here as F. sambucinum species complex lineage 1 [FSAMSC-1]) together with sequencing a portion of the translation elongation factor 1-α (TEF1) gene. One strain was discovered that appeared to be closely related to but phylogenetically distinct from F. praegraminearum based on the relatively low 97.7% TEF1 identity and positive genotype obtained with one of the two F. praegraminearum species-specific MLGT probes. Molecular phylogenetic analyses of a 10-gene data set resolved this novel FSAMSC-1 species and F. praegraminearum as sisters. Formally described herein as F. subtropicale, it is phenotypically distinct from the 22 other FSAMSC-1 species in that it produces mostly 1-3-septate macroconidia. Whole-genome sequence data were used to predict its potential to produce mycotoxins. Chemical analyses confirmed that F. subtropicale could produce the mycotoxins 4,15-diacetylnivalenol, butenolide, culmorin, and fusarin C in vitro, and the pathogenicity experiment revealed that F. subtropicale could infect but not spread in susceptible hard red spring wheat cultivar "Norm."

The Distribution of Miniature Impala Elements and SIX Genes in the Fusarium Genus is Suggestive of Horizontal Gene Transfer

The mimp family of miniature inverted-repeat transposable elements was previously found only in genomes of Fusarium oxysporum and is contextually associated with virulence genes in this species. Through extensive comparative analysis of 83 F. oxysporum and 52 other Fusarium genomes, we uncovered the distribution of different mimp families throughout the genus. We show that (i) mimps are not exclusive to F. oxysporum; (ii) pathogenic isolates generally possess more mimps than non-pathogenic strains and (iii) two isolates of F. hostae and one F. proliferatum isolate display evidence for horizontal transfer of genetic material to or from F. oxysporum. Multiple instances of mimp elements identical to F. oxysporum mimps were encountered in the genomes of these isolates. Moreover, homologs of effector genes (SIX1, 2, 6, 7, 11 and FomAVR2) were discovered here, several with very high (97-100%) pairwise nucleotide sequence identity scores. These three strains were isolated from infected flower bulbs (Hyacinthus and Lilium spp.). Their ancestors may thus have lived in close proximity to pathogenic strains of F. oxysporum f. sp. hyacinthi and f. sp. lilii. The Fo f. sp. lycopersici SIX2 effector gene was found to be widely distributed (15/18 isolates) throughout the F. fujikuroi species complex, exhibiting a predominantly vertical inheritance pattern. These findings shed light on the potential evolutionary mechanism underlying plant-pathogenicity in Fusarium and show that interspecies horizontal gene transfer may have occurred.

Symptomatic Citrus trees reveal a new pathogenic lineage in Fusarium and two new Neocosmospora species

The diversity of fusaria in symptomatic Citrus trees in Greece, Italy and Spain was evaluated using morphological and molecular multi-locus analyses based on fragments of the calmodulin (CAM), intergenic spacer region of the rDNA (IGS), internal transcribed spacer region of the rDNA (ITS), large subunit of the rDNA (LSU), RNA polymerase largest subunit (RPB1), RNA polymerase second largest subunit (RPB2), translation elongation factor 1-alpha (EF-1α) and beta-tubulin (TUB) genes. A total of 11 species (six Fusarium spp., and five Neocosmospora spp.) were isolated from dry root rot, crown, trunk or twig canker or twig dieback of citrus trees. The most commonly isolated species were Fusarium sarcochroum, F. oxysporum and Neocosmospora solani. Three new Fusarium species are described, i.e., F. citricola and F. salinense belonging to the newly described F. citricola species complex; and F. siculi belonging to the F. fujikuroi species complex. Results of pathogenicity tests showed this new complex to include prominent canker causing agents affecting several Citrus spp. In addition, two new species are described in Neocosmospora, named N. croci and N. macrospora, the latter species being clearly differentiated from most members of this genus by producing large, up to nine-septate sporodochial conidia.

Two new species of the Fusarium fujikuroi species complex isolated from the natural environment

Two new species in the Fusarium fujikuroi species complex (FFSC) are introduced. One of these, represented by strain CBS 454.97 was isolated from plant debris (Striga hermonthica) in the Sudan, while the second, represented by strains CBS 119850 and CBS 483.94, which originated from soil in Australia. Molecular analyses were performed including TEF1 spanning 576 bp region, 860 bp region of rPB2, and 500 bp BT2 region. Phylogenetic trees based on these regions showed that the two species are clearly distinct from all known taxa in the F. fujikuroi species complex. Based on phenotypic, physiological characters and molecular data, we introduce Fusarium sudanense and Fusarium terricola as novel species in the complex.