Emergence of fungal hybrids - Potential threat to humans

Fungal hybrids arise through the interbreeding of distinct species. This hybridization process fosters increased genetic diversity and the emergence of new traits. Mechanisms driving hybridization include the loss of heterozygosity, copy number variations, and horizontal gene transfer. Genetic mating barriers, changes in ploidy, chromosomal instability, and genomic diversity influence hybridization. These factors directly impact the fitness and adaptation of hybrid offspring. Epigenetic factors, including DNA methylation, histone modifications, non-coding RNAs, and chromatin remodelling, play a role in post-mating isolation in hybrids. In addition to all these mechanisms, successful hybridization in fungi is ensured by cellular mechanisms like mitochondrial inheritance, transposable elements, and other genome conversion mechanisms. These mechanisms support hybrid life and enhance the virulence and pathogenicity of fungal hybrids, which provoke diseases in host organisms. Recent advancements in sequencing have uncovered fungal hybrids in pathogens like Aspergillus, Candida, and Cryptococcus. Examples of these hybrids, such as Aspergillus latus, Candida metapsilosis, and Cryptococcus neoformans, induce severe human infections. Identifying fungal hybrids is challenging due to their altered genome traits. ITS sequencing has emerged as a promising method for diagnosing these hybrids. To prevent the emergence of novel hybrid fungal pathogens, it is crucial to develop effective diagnostic techniques and closely monitor pathogenic fungal populations for signs of hybridization. This comprehensive review delves into various facts about fungal hybridization, including its causes, genetic outcomes, barriers, diagnostic strategies, and examples of emerging fungal hybrids. The review emphasises the potential threat that fungal hybrids pose to human health and highlights their clinical significance.