[Abstract unavailable

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. Previously (Geiser et al. 2013; Phytopathology 103:400-408. 2013), the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani Species Complex (FSSC). Subsequently, this concept was challenged by one research group (Lombard et al. 2015 Studies in Mycology 80: 189-245) who proposed dividing Fusarium into seven genera, including the FSSC as the genus Neocosmospora, with subsequent justification based on claims that the Geiser et al. (2013) concept of Fusarium is polyphyletic (Sandoval-Denis et al. 2018; Persoonia 41:109-129). Here we test this claim, and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species recently described as Neocosmospora were recombined in Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural and practical taxonomic option available.

A new myosin motor-like chitin synthase gene, chsVb, has been identified in the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici. Phylogenetic analysis of the deduced amino acid sequence of the chsVb chitin synthase 2 domain (CS2) revealed that ChsVb belongs to class VII chitin synthases. The ChsVb myosin motor-like domain (MMD) is shorter than the MMD of class V chitin synthases and does not contain typical ATP-binding motifs. Targeted disrupted single (⌬chsVb) and double (⌬chsV ⌬chsVb) mutants were unable to infect and colonize tomato plants or grow invasively on tomato fruit tissue. These strains were hypersensitive to compounds that interfere with fungal cell wall assembly, produced lemon-like shaped conidia, and showed swollen balloon-like structures in hyphal subapical regions, thickened walls, aberrant septa, and intrahyphal hyphae. Our results suggest that the chsVb gene is likely to function in polarized growth and confirm the critical importance of cell wall integrity in the complex infection process of this fungus.In order to establish successful infection, fungal pathogens must overcome highly effective, constitutive physical and chemical barriers, employing a range of different infection strategies. These strategies may be specific to a particular fungal species according to the nature of the host surface, and within a single species, they may depend on the type of spores initiating the infection process. A number of important steps in the infection process are common to all strategies, including adhesion to the surface of the plant, penetration of the plant surface, and acquisition of nutrients from the plant cells (18). Hyphae of plant and animal pathogenic filamentous fungi navigate on the underlying surface topography by thigmotropism in order to locate points of weakened surface integrity to gain vulnerable sites for invasion (18,15). These sites are penetrated mechanically by expansion of the growing hyphal tips. Furthermore, fungal hyphae have been predicted to resist, at their tips, an opposing resistant force exerted by 8% (wt/vol) agar (28). These forces are related to the cell turgor pressure acting against the surface of a substrate at cell expansion places. Thus, fungal morphogenesis is an essential component for host invasion (16) and, at the same time, for establishing the correct fungal cell wall biogenesis.Chitin, a microfibrillar ␤-1,4-linked homopolymer of N-acetylglucosamine (GlcNAc) (5), is considered to be a relatively minor but structurally important component of fungal cell walls. While in yeast (Saccharomyces cerevisiae), chitin constitutes 1 to 2% of the total dry weight, for filamentous fungi, the chitin content has been reported to reach up to 10 to 20% (5). Chitin seems to be present in all eukaryote kingdoms except Plantae. Thus, chitin and its biosynthesis are potentially interesting targets for the discovery of novel fungicides against phytopathogenic fungi. Chitin synthesis on the plasma membrane occurs by the extrusion of nascent chains into the cell wall ...

This article is to alert medical mycologists and infectious disease specialists of recent name changes of medically important species of the filamentous mold Fusarium. Fusarium species can cause localized and life-threating infections in humans. Of the 70 Fusarium species that have been reported to cause infections, close to one-third are members of the Fusarium solani species complex (FSSC), and they collectively account for approximately two-thirds of all reported Fusarium infections. Many of these species were recently given scientific names for the first time by a research group in the Netherlands, but they were misplaced in the genus Neocosmospora. In this paper, we present genetic arguments that strongly support inclusion of the FSSC in Fusarium. There are potentially serious consequences associated with using the name Neocosmospora for Fusarium species because clinicians need to be aware that fusaria are broadly resistant to the spectrum of antifungals that are currently available.

In the fungal pathogen Fusarium oxysporum, vegetative hyphal fusion triggers nuclear mitotic division in the invading hypha followed by migration of a nucleus into the receptor hypha and degradation of the resident nucleus. Here we examined the role of autophagy in fusion-induced nuclear degradation. A search of the F. oxysporum genome database for autophagy pathway components identified putative orthologs of 16 core autophagy-related (ATG) genes in yeast, including the ubiquitin-like protein Atg8, which is required for the formation of autophagosomal membranes. F. oxysporum Foatg8D mutants were generated in a strain harboring H1-cherry fluorescent protein (ChFP)-labeled nuclei to facilitate analysis of nuclear dynamics. The Foatg8D mutants did not show MDC-positive staining in contrast to the wild type and the FoATG8-complemented (cFoATG8) strain, suggesting that FoAtg8 is required for autophagy in F. oxysporum. The Foatg8D strains displayed reduced rates of hyphal growth, conidiation, and fusion, and were significantly attenuated in virulence on tomato plants and in the nonvertebrate animal host Galleria mellonella. In contrast to wild-type hyphae, which are almost exclusively composed of uninucleated hyphal compartments, the hyphae of the Foatg8D mutants contained a significant fraction of hyphal compartments with 2 or more nuclei. The increase in the number of nuclei per hyphal compartment was particularly evident after hyphal fusion events. Timelapse microscopy analyses revealed abnormal mitotic patterns during vegetative growth in the Foatg8D mutants. Our results suggest that autophagy mediates nuclear degradation after hyphal fusion and has a general function in the control of nuclear distribution in F. oxysporum.