The phoma-like dilemma

Abstract

Species of Didymellaceae have a cosmopolitan distribution and are geographically widespread, occurring in diverse ecosystems. The family includes several important plant pathogenic fungi associated with fruit, leaf, stem and root diseases on a wide variety of hosts, as well as endophytic, saprobic and clinically relevant species. The Didymellaceae was recently revised based on morphological and phylogenetic analyses of ex-type strains subjected to DNA sequencing of partial gene data of the LSU, ITS, rpb2 and tub2 loci. Several poly- and paraphyletic genera, including Ascochyta , Didymella and Phoma were redefined, along with the introduction of new genera. In the present study, a global collection of 1 124 Didymellaceae strains from 92 countries, 121 plant families and 55 other substrates, including air, coral, human tissues, house dust, fungi, insects, soil, and water were examined via multi-locus phylogenetic analyses and detailed morphological comparisons, representing the broadest sampling of Didymellaceae to date. Among these, 97 isolates representing seven new genera, 40 new species and 21 new combinations were newly introduced in Didymellaceae . In addition, six epitypes and six neotypes were designated to stabilise the taxonomy and use of older names. A robust, multi-locus reference phylogenetic tree of Didymellaceae was generated. In addition, rpb2 was revealed as the most effective locus for the identification of Didymellaceae at species level, and is proposed as a secondary DNA marker for the family.

Identification and Characterization of Leaf-Inhabiting Fungi from Castanea Plantations in China

“…Notes— Didymella is a famous pathogenic genus mainly occurring on plant leaves [ 33 , 34 , 35 , 36 , 37 ]. Phoma-like species are difficult to identify to the genus and species level due to a lack of good characteristics, making molecular data are essential during species identification [ 34 , 35 , 37 ]. The new isolates (CFCC 54343 and SM24B) from Castanea mollissima grouped with Didymella coffeae-arabicae on Coffea arabica with high statistical support ( Figure A4 ).…”

Setting scientific names at all taxonomic ranks in italics facilitates their quick recognition in scientific papers

“…Likewise, the name Phoma is attributed to species that cluster in a monophyletic clade along with the type species, Phoma herbarum , whereas species with a phoma-like morphology refers to coelomycetous fungi with phialidic conidiogenous cells, and hyaline, smooth, aseptate conidia. These organisms could belong to more than 30 genera, most of which cluster in Didymellaceae , or in other families of Dothideomycetes (Hou et al 2020 ).…”

Cryptic diversity found in Didymellaceae from Australian native legumes

“…The Didymellaceae was established to accommodate Ascochyta, Didymella, and other allied Phoma-like genera (de Gruyter et al 2009). To date, more than 5,400 species from 31 genera have been recorded, including recently established genera such as Dimorphoma and Macroascochyta (Hou et al 2020). Species of Didymellaceae are cosmopolitan and occupy a broad range of environments.…”

“…Many species are plant pathogens that cause leaf and stem lesions, often with a broad host range (Aveskamp et al 2009;Aveskamp et al 2010;Chen et al 2015b). Multilocus phylogenetics and a polyphasic approach to classify species have helped to revise taxa and refine systematic relationships in the Didymellaceae (Aveskamp et al 2009Aveskamp et al 2010;Chen et al 2015a, de Gruyter 2012Hou et al 2020).…”