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In opportunistic human pathogenic fungi, changes in gene expression play a crucial role in the progression of growth stages from early spore germination through host infection. Comparative transcriptomics between diverse fungal pathogens and non-pathogens provided insights into regulatory mechanisms behind the initiation of infectious processes. 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 of spore germination. Ancestral status of gene expression was inferred for nodes along the phylogeny. By comparing expression patterns of the SCOGs with their most recent common ancestor (MRCA), we identified genes that exhibit divergent levels of expression during spore germination when comparing fungal pathogens to non-pathogens. We focused on genes related to the MAPK pathway, nitrogen metabolism, asexual development, G-protein signaling, and conidial-wall integrity. Notably, orthologs of the transcription activator abaA, a known central regulator of conidiation, exhibited significant divergence in gene expression in F. oxysporum. This dramatic expression change in abaA was accompanied by structural modifications of phialides in F. oxysporum, and revealed how these changes impact development of offspring, formation of aerial hyphae, spore production, and pathogenicity. Our research provides insights into ecological adaptations observed during the divergence of these species, specifically highlighting how divergence in gene expression during spore germination contributes to their ability to thrive in distinct environments. 

Fusarium head blight (FHB) is one of the most devastating diseases of cereal crops, causing severe reduction in yield and quality of grain worldwide. In the United States, the major causal agent of FHB is the mycotoxigenic fungus, Fusarium graminearum. The contamination of grain with mycotoxins, including deoxynivalenol and zearalenone, is a particularly serious concern due to its impact on the health of humans and livestock. For the past few decades, multidisciplinary studies have been conducted on management strategies designed to reduce the losses caused by FHB. However, effective management is still challenging due to the emergence of fungicidetolerant strains of F. graminearum and the lack of highly resistant wheat and barley cultivars. This review presents multidisciplinary approaches that incorporate advances in genomics, genetic-engineering, new fungicide chemistries, applied biocontrol, and consideration of the disease cycle for management of FHB.