Cryptic diversity found in Didymellaceae from Australian native legumes

Abstract

Ascochyta koolunga (Didymellaceae, Pleosporales) was first described in 2009 (as Phoma koolunga) and identified as the causal agent of Ascochyta blight of Pisum sativum (field pea) in South Australia. Since then A. koolunga has not been reported anywhere else in the world, and its origins and occurrence on other legume (Fabaceae) species remains unknown. Blight and leaf spot diseases of Australian native, pasture and naturalised legumes were studied to investigate a possible native origin of A. koolunga. Ascochyta koolunga was not detected on native, naturalised or pasture legumes that had leaf spot symptoms, in any of the studied regions in southern Australia, and only one isolate was recovered from P. sativum. However, we isolated five novel species in the Didymellaceae from leaf spots of Australian native legumes from commercial field pea regions throughout southern Australia. The novel species were classified on the basis of morphology and phylogenetic analyses of the internal transcribed spacer region and part of the RNA polymerase II subunit B gene region. Three of these species, Nothophoma garlbiwalawardasp. nov., Nothophoma naiawusp. nov. and Nothophoma ngayawangsp. nov., were isolated from Senna artemisioides. The other species described here are Epicoccum djirangnandirisp. nov. from Swainsona galegifolia and Neodidymelliopsis tinkyukukusp. nov. from Hardenbergia violacea. In addition, we report three new host-pathogen associations in Australia, namely Didymella pinodes on S. artemisioides and Vicia cracca, and D. lethalis on Lathyrus tingitanus. This is also the first report of Didymella prosopidis in Australia.

Plants control the structure of mycorrhizal and pathogenic fungal communities in soil in a 50-year maize monoculture experiment

“…was bound by a non-significant negative correlation with maize biomass yields. Didymella is one of the 31 genera of the family Didymellaceae that includes cosmopolitan polyphagous pathogens damaging the stems and leaves of plants growing in diverse environments (Keirnan et al 2021). Didymella sancta (syn.…”

Survey and Identification of Didymellaceae Causing Stem Canker Disease of Eucalyptus (E. camaldulensis) in Ethiopia

“…Based on the sequence and phylogenetic study, the fungal species were identified as D. coffeaearabicae and D. pinodella. According to Chen et al (2017) and Keirnan et al (2021), the genus Didymella consists of 35 known species that are widely distributed in both ornamentals and woody plants. Ahmadpour et al (2017) reported that Didymella species such as D. microchlamydospora cause dieback and stem necrosis diseases in plants.…”

The Genus Phoma: What We Know and What We Need to Know?

“…Consequently, this results in discrepancies and misidentifications. Increasingly, in order to achieve the correct identification of Phoma sensu lato, secondary metabolites, the protein profile, chemotaxonomy and nucleotide sequences using modern molecular techniques are being examined (Aveskamp et al 2008(Aveskamp et al , 2010Rai et al 2014;Keirnan et al 2021). Although the internal transcribed spacers (ITS) have been allied as the standard DNA barcode for fungi (Schoch et al 2012), it turned out to not be sufficient to distinguish all Phoma species.…”

“…The Didymellaceae was established to accommodate Phoma, Ascochyta, Didymella and other allied Phoma-like genera (de Gruyter et al 2009;Aveskamp et al 2010;Keirnan et al 2021). To date, more than 5.400 species from 36 genera have been recorded, including recently established genera such as Dimorphoma and Macroascochyta (Hou et al 2020).…”

“…Multilocus phylogenetics and a polyphasic approach to classify species have helped to revise taxa and refine systematic relationships in the Didymellaceae (Aveskamp et al 2009a(Aveskamp et al , b, 2010de Gruyter et al 2009de Gruyter et al , 2012Chen et al 2015a;Hou et al 2020;Keirnan et al 2021). In fact, the easier access to DNA sequencing and online databases is ongoingly supporting the distinction of novel species; however, a large number of unknown Didymellaceae taxons still exist in nature, especially from previously ignored ecosystems and diverse substrates.…”