The newly described taxa were recovered from sixteen yeast strains collected from leaf surfaces across four Chinese provinces: Fujian, Guizhou, Hainan, and Henan. Rather than sampling diseased or symptomatic tissue, the researchers targeted apparently healthy leaves, an approach that reflects a growing recognition among mycologists that many plant-associated fungi persist in inconspicuous or asymptomatic states on their hosts. The isolation technique itself, an improved version of the spore-fall method, is elegantly simple. Fresh leaves were cut into small pieces and attached to the inner lid of a Petri dish using a thin layer of petroleum jelly, positioned above a nutrient agar medium containing yeast extract, malt extract, peptone, glucose, and a small amount of chloramphenicol to suppress bacterial competitors. As spores or yeast cells were released naturally from the leaf surfaces, they fell onto the medium below and formed colonies that could then be picked, purified, and preserved in glycerol-supplemented broth at very low temperatures for long-term study.

This passive capture method is particularly well suited to Taphrinales because of the peculiar life cycle these fungi exhibit. Most members of the genus Taphrina are dimorphic, meaning they alternate between two fundamentally different forms depending on their circumstances. The sexual morph is filamentous and strictly biotrophic, growing inside living plant tissue where it produces asci, the sac-like structures characteristic of ascomycete fungi, within infected host cells. The asexual morph, by contrast, is yeast-like and saprobic, reproducing by budding and growing readily on artificial media in the laboratory. Historically, these two forms were so different in appearance that they were described as separate genera, with the yeast phase assigned to Lalaria. Molecular analyses eventually demonstrated that the Lalaria anamorphs belonged within Taphrina itself, and a 2014 emendation formally combined each asexual morph with its corresponding sexual morph into single species, in accordance with the International Code of Nomenclature for Algae, Fungi, and Plants.

The laboratory characterization of the new isolates followed standard yeast taxonomy protocols, which involve a battery of physiological tests designed to distinguish closely related species. Colony morphology was assessed after a week of incubation on YM agar, and cell morphology was documented microscopically after three days in liquid culture. Fermentation capability was tested in Durham tubes over two weeks, with gas production indicating a positive reaction. Carbon assimilation and nitrogen assimilation tests, each requiring nearly a month of incubation at twenty degrees Celsius, probed the metabolic repertoire of each strain. Additional tests examined pseudohyphae formation on corn meal agar, growth across a temperature gradient from fifteen to thirty-seven degrees Celsius, vitamin requirements, tolerance to acetic acid, cycloheximide, and saline conditions, starch-like polysaccharide production detected with Lugol’s iodine, urease activity, and the Diazonium Blue B reaction, a diagnostic tool that helps differentiate basidiomycetous from ascomycetous yeasts.

Complementing these phenotypic observations, the researchers sequenced three genetic regions from each strain: the internal transcribed spacer region, the D1/D2 domain of the large subunit ribosomal RNA gene, and a portion of the mitochondrial small subunit ribosomal RNA gene. These three loci are workhorses of yeast systematics. The ITS region is widely used for species-level identification across fungi, the D1/D2 domain of the LSU provides complementary resolution among closely related yeasts, and the mitochondrial small subunit has proven especially informative for resolving relationships within Taphrinales, where nuclear loci alone sometimes show limited divergence. Polymerase chain reaction protocols were carefully optimized for each region, with distinct annealing temperatures and cycle numbers, and the resulting sequences were edited to remove primer sequences and low-quality bases before being assembled into consensus reads and compared against the GenBank database.

The decision to describe a new genus rather than simply adding more species to Taphrina reflects a substantive phylogenetic finding. Two of the isolated strains, now named Srisukozyma ovata and Srisukozyma musae, were found to occupy a distinct lineage separate from the core Taphrina clade, warranting recognition at the genus level. The generic name honors contributions to yeast taxonomy, and its establishment brings the number of genera recognized within Taphrinaceae to a slightly expanded roster. The remaining five new species, Taphrina aspidistrae, T. cunninghamiae, T. foliicola, T. fujianensis, and T. guizhouensis, were placed within Taphrina itself based on combined molecular and morphological evidence. Each species epithet offers a clue to its origin or host: aspidistrae likely references the host genus Aspidistra, cunninghamiae points to Cunninghamia, the Chinese fir, foliicola translates roughly as leaf-dwelling, and the remaining two names acknowledge the provinces of Fujian and Guizhou where the strains were collected.

The broader context of this work highlights how much remains unknown about fungal diversity even in well-studied groups. Taphrina was established by Fries in 1832 with T. populina as its type species, and over nearly two centuries the genus accumulated nearly a hundred scientific names. However, taxonomic consolidation, driven by low DNA sequence divergence among described taxa and the unfortunate reality that roughly seventy percent of species were never deposited in culture collections, reduced the accepted count to twenty-eight species by 2011. Subsequent work added nine more, bringing the total to thirty-eight valid species before the present study. Against this backdrop, the discovery of five additional Taphrina species and an entirely new genus from a modest sampling effort in a single country is striking. It suggests that the global diversity of Taphrinales is substantially underestimated, particularly in understudied regions of Asia.

China exemplifies this gap. Before this study, only four Taphrina species had been reported from the country: T. cerasi, T. deformans, T. mume, and T. pruni. The addition of five new species and two new genus-level taxa from leaf surfaces alone represents a more than doubling of documented national diversity for the genus. Given that China spans an enormous range of climates and hosts, from tropical Hainan to temperate northern provinces, and harbors exceptional plant diversity including many ancient lineages, the actual richness of Taphrinales in the region is likely far greater than current records indicate.

The ecological and economic significance of Taphrinales extends well beyond taxonomy. Taphrina deformans, the agent of peach leaf curl, is among the most extensively studied plant-pathogenic fungi worldwide, and all known peach and nectarine cultivars are susceptible to infection. The characteristic severe distortion and reddening of infected leaves is linked to the production of indole-3-acetic acid, a plant hormone that the fungus synthesizes and that disrupts normal host development. Taphrina flavorubra causes plum pocket, a disease in which infected fruits become abnormally enlarged, deformed, and spongy in texture. Taphrina betulina reduces both the mean height and diameter of infected birch trees, with potential consequences for timber production in short-rotation forestry. Other species attack poplars, elms, flowering cherries, and oaks, and some members of the order even parasitize ferns, an unusual host range among ascomycetes that hints at an ancient evolutionary history.

That antiquity is one of the most intriguing aspects of the group. Taphrina was once classified among the so-called archiascomycetes, a term reflecting the hypothesis that these fungi diverged early from the main ascomycete lineage. The class Taphrinomycetes was formally proposed in 1997 to accommodate these archiascomycete lineages. Understanding the diversity and distribution of Taphrinales therefore has implications not only for plant pathology and ecology but also for reconstructing the deep evolutionary history of the fungal kingdom. Each newly described species adds a data point to these broader questions, and the availability of living cultures, preserved in glycerol at minus eighty degrees Celsius and deposited with sequence data in GenBank, ensures that future researchers will be able to build on this foundation.

The study also illustrates the value of combining classical and molecular approaches. Phenotypic comparisons with related genera and species remain essential for species delimitation, particularly in groups where sequence divergence is modest, and the careful documentation of colony appearance, cell morphology, and physiological capabilities provides a durable record that complements genetic data. The deposition of all novel taxonomic descriptions and proposed names in the MycoBank database ensures that the new names are formally registered and citable under the rules of botanical and mycological nomenclature. As molecular surveys of environmental samples continue to reveal vast numbers of undocumented fungal lineages, studies like this one, which connect sequences to named, cultured, and morphologically characterized organisms, will remain indispensable for translating the hidden diversity of fungi into a form that ecologists, pathologists, and evolutionary biologists can actually use.

Subject of Research: Phylogenetic taxonomy of Taphrinales yeasts isolated from leaf surfaces in China

Article Title: Phylogenetic analysis of the genus Taphrina : proposal of one new genus and seven new species ( Taphrinales , Taphrinomycetes ) from China

Article References: Chai, C.-Y., Cai, D.-Y., Song, B.-Y., Wang, R.-X., & Hui, F.-L. (2026). Phylogenetic analysis of the genus Taphrina: proposal of one new genus and seven new species (Taphrinales, Taphrinomycetes) from China. IMA Fungus, 17, Article e187200. https://doi.org/10.3897/imafungus.17.187200

Image Credits: AI Generated

DOI: 10.3897/imafungus.17.187200

Keywords: Taphrina, Taphrinales, yeast taxonomy, phylogenetics, fungal diversity, China, phylloplane, new species, Srisukozyma, ascomycetes, plant-associated fungi, ITS barcode