Are tropical fungal endophytes hyperdiverse?

TLDR

Fungal endophytes are ubiquitous, inhabiting healthy tissues of all examined plant species and constituting a significant yet often overlooked component of fungal biodiversity. The study quantified endophyte colonization, richness, host preference, and spatial variation in healthy leaves of two co‑occurring understory tree species in a lowland tropical forest of central Panama. From 83 fully colonized leaves, 418 morphospecies (≈347 genetically distinct taxa) were isolated, most being singletons, and evidence of host preference and spatial heterogeneity indicates that tropical endophytes may be hyperdiverse, implying that excluding them markedly underestimates fungal species diversity.

Abstract

Fungal endophytes are ubiquitous fungi that inhabit healthy plant tissues without causing disease. Endophytes have been found in every plant species examined to date and may be important, but often overlooked, components of fungal biodiversity. In two sites in a lowland, moist tropical forest of central Panama, we quantified endophyte colonization patterns, richness, host preference, and spatial variation in healthy leaves of two co‐occurring, understory tree species [ Heisteria concinna (Olacaceae) and Ouratea lucens (Ochnaceae)]. From 83 leaves, all of which were colonized by endophytes, we isolated 418 endophyte morphospecies (estimated 347 genetically distinct taxa), most of which were represented by only a single isolate (59%). Among morphospecies encountered in more than one leaf (nonsingletons), we found evidence of host preference and spatial heterogeneity using both morphospecies frequencies and presence/absence records. Based on these data, we postulate that tropical endophytes themselves may be hyperdiverse and suggest that extrapolative estimates that exclude them will markedly underestimate fungal species diversity.