Comparative transcriptional analysis reveals gene expression changes in spore germination of opportunistic pathogenic fungi

In opportunistic human pathogenic fungi, changes in gene expression play a crucial role in the evolution of growth stages from early spore germination through host infection. Comparative transcriptomics from diverse fungal pathogens along closely related non-pathogenic model provided insights of regulatory mechanisms behind the initiation of infectious processes by different fungi. We examined the gene expression patterns of 3,845 single-copy orthologous genes (SCOGs) across five phylogenetically distinct species, including the opportunistic human pathogens Fusarium oxysporum, Aspergillus fumigatus, and A. nidulans, and nonpathogenic species Neurospora crassa and Trichoderma asperelloides, at four sequential stages spore germination. The gene expression profile of conidial germination stages of Fusarium oxysporum NRRL32931, Aspergillus fumigatus AF293, and Aspergillus nidulans A4 on a standard medium (Bird medium) was generated. Four designated germination stages, including swelling conidia (stage 1), polar growth (stage 2), doubling of the long axis (stage 3), and first hyphal branching formation (stage 4), were examined to generate the gene expression profile.