About this Research Topic
In recent years, human fungal pathogens have received increasing attention, with several of these species responsible for prevalent diseases that are associated with high mortality rates. The major human pathogens belong to the genera Candida, Aspergillus, and Cryptococcus, although a wide variety of highly diverse fungal species are clinically relevant, including those from basal lineages such as the order Mucorales.
Historically, most human fungal pathogens were thought to propagate primarily through clonal asexual reproduction. During this process, cells can still accumulate mutations and can undergo a variety of genomic rearrangements and ploidy alterations. Such changes can contribute to adaptive changes associated with enhanced pathogenicity, resistance to antifungal drugs and persistence in chronic infections. Parasexual cycles, as observed in Candida albicans, represent an opportunity to allow gene flow between such asexual lineages. The parasexual cycle is also important as another potential source for generating genetic diversity that may drive host adaptation.
Full sexual cycles (that include meiosis) can also impact important fungal attributes such as pathogenicity and antifungal drug resistance. Although long overlooked, discoveries of complete sexual cycles in species such as Aspergillus fumigatus and Candida lusitaniae has widened our understanding of how sex occurs and how it may contribute to pathogenesis. Indeed, population genetic studies continue to reveal that supposedly asexual fungal lineages exhibit evidence of a recombining population structure. This may indicate cryptic sexual cycles are still to be discovered in multiple species from across the fungal kingdom. In addition, the discovery of unisexual reproduction in several prominent pathogens has pushed the boundaries by which sex can occur in nature. Furthermore, evidence of syngamy-independent meiotic gene expression during unisexual reproduction or during infectious progression in Cryptococcus neoformans reveals that meiosis-related processes may be important for reasons unrelated to genetic variation. Despite exciting advances in these areas, however, links between genomic variation, adaptation, and pathogenicity are still far from understood.
This Research Topic will include Original Research, Reviews, and Methods papers highlighting the genetic basis and role of sexual, parasexual, and unisexual cycles in important human fungal pathogens. These reports will expand our understanding of how these processes drive adaptive genetic changes that contribute to key traits such as resistance to antifungal drugs and host adaptation.
Historically, most human fungal pathogens were thought to propagate primarily through clonal asexual reproduction. During this process, cells can still accumulate mutations and can undergo a variety of genomic rearrangements and ploidy alterations. Such changes can contribute to adaptive changes associated with enhanced pathogenicity, resistance to antifungal drugs and persistence in chronic infections. Parasexual cycles, as observed in Candida albicans, represent an opportunity to allow gene flow between such asexual lineages. The parasexual cycle is also important as another potential source for generating genetic diversity that may drive host adaptation.
Full sexual cycles (that include meiosis) can also impact important fungal attributes such as pathogenicity and antifungal drug resistance. Although long overlooked, discoveries of complete sexual cycles in species such as Aspergillus fumigatus and Candida lusitaniae has widened our understanding of how sex occurs and how it may contribute to pathogenesis. Indeed, population genetic studies continue to reveal that supposedly asexual fungal lineages exhibit evidence of a recombining population structure. This may indicate cryptic sexual cycles are still to be discovered in multiple species from across the fungal kingdom. In addition, the discovery of unisexual reproduction in several prominent pathogens has pushed the boundaries by which sex can occur in nature. Furthermore, evidence of syngamy-independent meiotic gene expression during unisexual reproduction or during infectious progression in Cryptococcus neoformans reveals that meiosis-related processes may be important for reasons unrelated to genetic variation. Despite exciting advances in these areas, however, links between genomic variation, adaptation, and pathogenicity are still far from understood.
This Research Topic will include Original Research, Reviews, and Methods papers highlighting the genetic basis and role of sexual, parasexual, and unisexual cycles in important human fungal pathogens. These reports will expand our understanding of how these processes drive adaptive genetic changes that contribute to key traits such as resistance to antifungal drugs and host adaptation.
Keywords: human fungal pathogens, propagation, sexual cycles, genetics, fungal reproduction
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