Translucidithyrium thailandicum gen. et sp. nov.: a new genus in Phaeothecoidiellaceae

Exploring ascomycete diversity in Yunnan, China I: resolving ambiguous taxa in Phaeothecoidiellaceae and investigating conservation implications of fungi

Yunnan, located in southwestern China, is known for its high fungal diversity, and many of which are endemic to the region. As part of our ongoing studies on fungi in Yunnan, we introduce two new genera in Phaeothecoidiellaceae (Mycosphaerellales), to accommodate one Repetophragma-like and another Stomiopeltis-like taxa. Pseudorepetophragma gen. nov. is introduced herein as a monotypic genus to accommodate P. zygopetali comb. nov.(≡ Repetophragma zygopetali), whereas Pseudostomiopeltis gen. nov. is introduced to accommodate Ps. xishuangbannaensis gen. et sp. nov. and Ps. phyllanthi comb. nov.(≡ Stomiopeltis phyllanthi), based on a new collection from Yunnan. In addition, Stomiopeltis sinensis is transferred to Exopassalora as E. sinensis comb. nov. due to its phylogenetic affinity and grouped with E. zambiae, the generic type of Exopassalora. This study provides new insights into the biodiversity of fungal species in this region and adds to our understanding of their ecological roles, as well as the resolution to ambiguous taxa in Phaeothecoidiellaceae.

The insights into the evolutionary history of Translucidithyrium: based on a newly-discovered species

During the field studies, a Translucidithyrium-like taxon was collected in Xishuangbanna of Yunnan Province, during an investigation into the diversity of microfungi in the southwest of China. Morphological observations and phylogenetic analysis of combined LSU and ITS sequences revealed that the new taxon is a member of the genus Translucidithyrium and it is distinct from other species. Therefore, Translucidithyrium chinensesp. nov. is introduced here. The Maximum Clade Credibility (MCC) tree from LSU rDNA of Translucidithyrium and related species indicated the divergence time of existing and new species of Translucidithyrium was crown age at 16 (4–33) Mya. Combining the estimated divergence time, paleoecology and plate tectonic movements with the corresponding geological time scale, we proposed a hypothesis that the speciation (estimated divergence time) of T. chinense was earlier than T. thailandicum. Our findings provided new insights into the species of Translucidithyrium about ecological adaptation and speciation in two separate areas.

Stealth Pathogens: The Sooty Blotch and Flyspeck Fungal Complex

Sooty blotch and flyspeck (SBFS) fungi produce superficial, dark-colored colonies on fruits, stems, and leaves of many plant genera. These blemishes are economically damaging on fruit, primarily apple and pear, because they reduce the sale price of fresh fruit. Fungicide spray programs can control SBFS but are costly and impair human and environmental health; thus, less chemically intensive management strategies are needed. Although the scientific study of SBFS fungi began nearly 200 years ago, recent DNA-driven studies revealed an unexpectedly diverse complex: more than 100 species in 30 genera of Ascomycota and Basidiomycota. Analysis of evolutionary phylogenetics and phylogenomics indicates that the evolution of SBFS fungi from plant-penetrating ancestors to noninvasive ectophytic parasites was accompanied by a massive contraction of pathogenicity-related genes, including plant cell wall-degrading enzymes and effectors, and an expansion of cuticle-degradation genes. This article reviews progress in understanding SBFS taxonomy and ecology and improving disease management. We also highlight recent breakthroughs in reconstructing the evolutionary origins of these unusual plant pathogens and delineating adaptations to their ectophytic niche.