Coral-associated marine fungi form novel lineages and heterogeneous assemblages

Abstract

Coral stress tolerance is intricately tied to the animal's association with microbial symbionts. The most well-known of these symbioses is that between corals and their dinoflagellate photobionts (Symbiodinium spp.), whose genotype indirectly affects whether a coral can survive cyclical and anthropogenic warming events. Fungi comprise a lesser-known coral symbiotic community whose taxonomy, stability and function is largely un-examined. To assess how fungal communities inside a coral host correlate with water temperature and the genotype of co-occurring Symbiodinium, we sampled Acropora hyacinthus coral colonies from adjacent natural pools with different water temperatures and Symbiodinium identities. Phylogenetic analysis of coral-associated fungal ribosomal DNA amplicons showed a high diversity of Basidiomycetes and Ascomycetes, including several clades separated from known fungal taxa by long and well-supported branches. Community similarity did not correlate with any measured variables, and total fungal community composition was highly variable among A. hyacinthus coral colonies. Colonies in the warmer pool contained more phylogenetically diverse fungal communities than the colder pool and contained statistically significant 'indicator' species. Four taxa were present in all coral colonies sampled, and may represent obligate associates. Messenger RNA sequenced from a subset of these same colonies contained an abundance of transcripts involved in metabolism of complex biological molecules. Coincidence between the taxonomic diversity found in the DNA and RNA analysis indicates a metabolically active and diverse resident marine fungal community.

Phytophthora×serendipitasp. nov. andP.×pelgrandis, two destructive pathogens generated by natural hybridization

“…Amplicon-based studies of environmental DNA reveal unknown fungal lineages and thousands of novel species, apparently comprising the majority of fungi in most ecosystems (Schadt et al 2003;Monchy et al 2011;Rosling et al 2011;Amend et al 2012;Tedersoo et al 2014). While these surveys provide great insight into habitats, distributions, and diversity of the vast and largely undescribed richness of fungal species, they provide little information on biological properties of the detected lineages and rarely can be linked to additional DNA sequences other than from the nuc ribosomal RNA operon.…”

Exploring the oceanic microeukaryotic interactome with metaomics approaches

“…A classic example of a holobiont would be a coral reef, which consists not only of the host and the dinoflagellate photosymbionts but also of marine fungi and other microorganisms (Amend et al 2012, del Campo et al 2016.…”

The roles of endolithic fungi in bioerosion and disease in marine ecosystems. II. Potential facultatively parasitic anamorphic ascomycetes can cause disease in corals and molluscs

“…Fungi have certainly been observed to grow faster and to reproduce at temperature optima, which are often comparatively higher than that of the marine environment where they occur. Some marine fungi can be locally more diverse at higher temperatures (Amend et al 2012). Other species appear to prefer colder environments (Wisshak and Porter 2006).…”