Journal of Fungi

Temperature limits jiaobai (Zizania latifolia) production by its symbiont, the smut fungus Ustilago esculenta, yet the cellular mechanisms underlying this thermal sensitivity remain poorly understood. In this study, we combined controlled temperature regimes, transmission electron microscopy, and RNA sequencing to dissect the fungal response to heat. A moderate 30/25 °C day/night regime was associated with the highest proportion of cells containing multivesicular bodies (MVBs; 65.0%) and the only detectable autophagosome-like structures (6.7%), whereas regimes incorporating 35 °C drove extensive vacuolar degradation and cytoplasmic rarefaction. Strikingly, the strongest MVB accumulation occurred with the fewest transcriptional changes among 126 endocytic, autophagic, and vacuolar genes, suggesting as a working hypothesis that temperature may primarily shape MVB homeostasis through post-transcriptional, flux-level regulation rather than wholesale transcriptional reprogramming. However, low numbers of MVB-related differentially expressed genes (DEGs) were not unique to the 30/25 °C regime: AT35/25 also had only eight MVB-related DEGs yet showed severe degradation, and T35 had numerous MVBs with only 14 MVB-related DEGs. These observations indicate that DEG counts alone cannot predict MVB abundance. The 30/25 °C regime, which qualitatively resembled the field phenotype, induced only 418 differentially expressed genes, whereas harsher regimes triggered broader transcriptional responses without corresponding increases in MVB abundance. These findings provide a cellular and transcriptional framework for understanding the heat sensitivity of jiaobai production, highlighting the importance of diurnal thermal rhythms and post-transcriptional regulation in fungal thermal acclimation.

Thelephora ganbajun is a highly valued edible ectomycorrhizal fungus, but the relationships between its natural distribution and growth and soil environmental conditions remain poorly understood. In this study, mycosphere soils and adjacent control soils were collected from seven geographic sites in Yunnan Province, China. Soil physicochemical properties, enzyme activities, untargeted metabolomics, and bacterial and fungal amplicon sequencing were integrated to characterize geographic variation in the belowground environment and its associations with fruiting-body metabolic phenotypes. Nutrient levels and enzyme activities differed between mycosphere and control soils, and the magnitude of these differences varied among sites. A total of 5006 metabolites were annotated, including 77 differential metabolites shared across all seven sites, although their directions of change were strongly site-dependent. Bacterial and fungal communities in mycosphere soils exhibited significant geographic differentiation. The first two axes of distance-based redundancy analysis cumulatively explained 50.04% and 56.73% of the variation in bacterial and fungal communities, respectively. Soil pH, alkali-hydrolyzable nitrogen, and available phosphorus emerged as key environmental factors, with the latter two significantly associated with both bacterial and fungal community structure. Procrustes analysis further revealed concordant geographic differentiation of the two microbial communities. The volatile, non-volatile, and free amino acid metabolic phenotypes of fruiting bodies were associated with different components of the belowground environment. These findings reveal geographic variation in the belowground environment of T. ganbajun during a single fruiting season and its associations with fruiting-body metabolic phenotypes, providing candidate environmental indicators for future habitat assessment.

Aim: This study evaluated the performance of the new Zybio EXS2600 Ex-Accuspec database and system in identifying clinical filamentous fungal pathogens, comparing it with the existing Bruker Filamentous Fungi Library 3.0 database and system. Background: Delayed and inaccurate diagnoses can significantly increase the risk of mortality associated with invasive mold infections. Recently, the identification of mold isolates using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has progressed beyond traditional morphological identification methods. Method: A total of 180 well-characterized clinical mold isolates, representing 23 species across 11 genera, were analyzed alongside eight reference strains from three genera. This analysis was conducted using the direct extraction method on both the EXS2600 and the Biotyper. The results were evaluated using both the manufacturer-recommended cutoff scores and lower cutoff scores. Result: Among the 180 clinical isolates, the EXS2600 achieved significantly higher identification rates than the Bruker Biotyper at both the species/species-complex level (57.2% vs. 17.2%) and genus level (82.8% vs. 45.6%) using the manufacturer-recommended score thresholds (both p < 0.001). When reduced score thresholds were applied, identification rates increased to 82.8% and 91.7% at the species/species-complex and genus levels, respectively, for the EXS2600, compared with 45.6% and 66.7% for the Bruker Biotyper (both p < 0.001). The EXS2600 system achieved high species-level identification rates for Aspergillus fumigatus (80.8%), Aspergillus flavus (93.8%), and dermatophytes (85.0%). In contrast, the Bruker Biotyper showed numerically higher species/species-complex-level identification rates for the Fusarium solani species complex (28.6%) and the Fusarium fujikuroi species complex (28.6%) compared with the EXS2600. Both systems showed limited identification performance for dematiaceous molds, while Trichophyton indotineae was not represented in the Bruker Biotyper database. Additionally, the EXS2600 offered a simpler sample preparation workflow compared with the Biotyper. Conclusions: Our results highlight the Zybio EXS2600 Ex-Accuspec database and system as a promising and reliable tool for the routine identification of filamentous fungi, demonstrating high identification rates and a relatively simple sample preparation procedure. Additionally, lowering the validity cutoff levels may improve the Zybio EXS2600 system’s performance.