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The phoma-like dilemma: Taxonomy and phylogenetic relationships in Didymellaceae

Summary

This research provides an updated classification system for an important family of fungi that includes many plant pathogens and beneficial species. The study examined over 1,100 fungal specimens to better understand their relationships and establish more accurate ways to identify them. This work impacts everyday life in several ways: • Helps farmers and agricultural workers better identify and manage crop diseases caused by these fungi • Improves food security by enabling better control of plant pathogens that affect important crops • Provides tools for more accurate and faster identification of potentially harmful fungi during quarantine inspections • Advances our understanding of fungal diversity in soil and other environments • Enables development of better biological control agents using beneficial species from this fungal family

Background

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.

Objective

To elucidate the taxonomy of a global collection of 1,124 phoma-like strains of Didymellaceae, including all isolates used in previous monographs deposited in the CBS culture collection. To revise the taxonomy of previously introduced genera and designate epitypes/neotypes to fix the application of older names where possible. To evaluate rpb2 as potential secondary species-level DNA barcode across all genera included in Didymellaceae.

Results

The study resolved 36 well-supported monophyletic clades representing 36 genera, of which seven are described as new. A total of 40 new species and 21 new combinations were introduced. Six epitypifications and six neotypifications were performed, and four basionyms were resurrected. The rpb2 gene proved highly effective as a secondary barcode, providing good resolution at both species and generic levels.

Conclusion

The study provides a comprehensive taxonomic revision of Didymellaceae based on the largest sampling to date, establishing a robust phylogenetic backbone for the family. The rpb2 gene is confirmed as an effective secondary barcode for species identification. The research reveals high diversity in soil environments and other unexplored habitats, suggesting many novel species await discovery.
  • Published in:Studies in Mycology,
  • Study Type:Taxonomic Study,
  • Source: PMC7452269
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