Conserved storage-carbohydrate metabolic modules are rewired during germination of Trichoderma asperelloides and...

Conidial germination requires rapid mobilization and reorganization of storage carbohydrates, yet the network architecture underlying this process remains poorly defined in filamentous fungi. Using quantitative GC-MS/MS profiling, we provide the first quantitative identification of major soluble sugar species across four germination stages of Trichoderma asperelloides T203 and compared them with four representative models in the Sordariomycetes (Metarhizium anisopliae, Cordyceps militaris, Fusarium graminearum, and Neurospora crassa). In T. asperelloides, mannitol was the most prevalent measured sugar in dormant conidia, declined sharply at polarity establishment, and partially recovered at later stages, while trehalose displayed a reciprocal increase and other sugars remained comparatively stable. Comparative analyses revealed distinct species-specific carbon storage strategies: Dormant conidia of T. asperelloides, M. anisopliae, and C. militaris were mannitol-enriched, whereas in N. crassa and F. graminearum glucose was the most abundant; after germination onset, most species shifted toward glucose accumulation, but T. asperelloides uniquely transitioned from mannitol to trehalose dominance before partial re-accumulation of mannitol. Integration of sugar profiles with time-resolved RNA-seq and Bayesian network inference revealed conserved core interactions but also lineage-specific divergences in mannitol/trehalose-associated central-carbon modules that correspond to distinct nutrient and lifestyle strategies during early colonization. A focused analysis in T. asperelloides uncovered extensive stage-dependent transcriptional remodeling of metabolic-process genes and a mannitol-centered module involving mpd1 and mtd1 (encoding mannitol-1-phosphate 5-dehydrogenase and mannitol dehydrogenase, respectively). Antisense-based knockdown of mpd1 strongly reduced its transcript levels and led to stage-dependent upregulation of mtd1. However, these changes left mannitol content, soluble-sugar profiles, germination dynamics, and growth on mannitol essentially unchanged. Together, our comparative metabolic-network analysis shows that conidial mannitol and trehalose metabolism in T. asperelloides is embedded in a flexible, partially redundant central-carbon framework, and establishes this species as a tractable model for systems-level dissection of sugar metabolic regulation during early fungal development and colonization.