No abstract

No abstract

No abstract

In this letter, we advocate recognizing the genus Fusarium as the sole name for a group that includes virtually all Fusarium species of importance in plant pathology, mycotoxicology, medicine, and basic research. This phylogenetically guided circumscription will free scientists from any obligation to use other genus names, including teleomorphs, for species nested within this clade, and preserve the application of the name Fusarium in the way it has been used for almost a century. Due to recent changes in the International Code of Nomenclature for algae, fungi, and plants, this is an urgent matter that requires community attention. The alternative is to break the longstanding concept of Fusarium into nine or more genera, and remove important taxa such as those in the F. solani species complex from the genus, a move we believe is unnecessary. Here we present taxonomic and nomenclatural proposals that will preserve established research connections and facilitate communication within and between research communities, and at the same time support strong scientific principles and good taxonomic practice.

No abstract

No abstract

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.

Plant cell transformation by Agrobacteriwun Iwefaciens involves the transfer of a single-stranded DNAprotein complex (T-complex) from the bacterium to the plant cell. One of the least understood and important aspects of this process is how the T-complex exits the bacterium. The eleven virB gene products have been proposed to specify the DNA export channel on the basis of their predicted hydrophobicity. To determine the cellular localization of the VirB proteins, two different cell fractionation methods were employed to separate inner and outer membranes. Seven VirB-specific antibodies were used on Western blots (immunoblots) to detect the proteins in the inner and outer membranes and soluble (containing cytoplasm and periplasm) fractions. VirB5 was in both the inner membrane and cytoplasm. Six of the VwrB proteins were detected in the membrane fractions only. Three of these, VWrB8, VirB9, and VWrBlO, were present in both inner and outer membrane fractions regardless of the fractionation method used. Three additional VwrB proteins, VirBi, VWrB4, and VWrB1I, were found mainly in the inner membrane fraction by one method and were found in both inner and outer membrane fractions by a second method. These results confirm the membrane localization of seven VirB proteins and strengthen the hypothesis that VirB proteins are involved in the formation of a T-DNA export channel or gate. That most of the VwrB proteins analyzed are found in both inner and outer membrane fractions suggest that they form a complex pore structure that spans both membranes, and their relative amounts in the two membrane fractions reflect their differential sensitivity to the experimental conditions. Agrobacterium tumefaciens has the unique ability to transfer DNA to plant cells. In nature, the transfer and expression of a specific fragment of DNA (T-DNA) cause a neoplastic growth on the plant host. In the laboratory, this DNA transfer phenomenon has been exploited by using disarmed vectors to introduce new genes into plants. The T-DNA and the components necessary for packaging and transfer of the single-stranded T-DNA (T-strand) (45) are encoded by the tumor-inducing (Ti) plasmid in A. tumefaciens. The virulence (vir) region contains four operons (virA, virG, virD, and virB) that encode proteins required for virulence on all hosts (44). Three additional operons (virE, virC, and virH) encode proteins that are required only on some hosts (25,44).The transfer of DNA from the bacterium to the plant cell involves at least seven recognizable steps. Of the bacterial components necessary for DNA transfer, only the first step is thought to be mediated by chromosomally encoded functions (reviewed in reference 5). The remaining steps involve proteins that are encoded by the vir region on the Ti plasmid (reviewed in reference 59). The seven steps are as follows: (i) the bacterium binds to a specific component of the plant cell surface; (ii) a bacterial membrane protein (VirA) recognizes signals released by a wounded plant cell and transduces the signal v...