Fungal endophytes live asymptomatically within leaf tissues and are found within all plant lineages. Endophytes are especially abundant and diverse in tropical rainforests, and current research examining the factors driving endophyte community composition have not yet examined the association between plant attributes, such as photosynthetic pathways and associated functional leaf traits to foliar fungal endophytes. The family Bromeliaceae is a monophyletic group of flowering plants that are often epiphytic, can use C3 or crassulacean acid metabolism (CAM) photosynthesis, and vary in functional leaf characteristics. This variation within one family offers an exciting opportunity to examine the relationship of photosynthetic pathways and functional leaf traits to fungal endophyte communities. The objectives of this study were to: (i) characterize the fungal endophyte communities in tropical epiphytic bromeliads, (ii) relate endophyte abundance, diversity, and community composition to C3 and CAM photosynthetic pathways, (iii) and identify functional leaf traits that are associated with endophyte community composition. We cultured fungal endophytes from the leaves of six bromeliad species, 10 individuals per species (N = 60), found in the canopy of a lowland tropical wet forest in Costa Rica. We used Sanger sequencing to aid in taxonomic grouping.
Results/Conclusions
Fungal communities in bromeliad leaves were dominated by the phyla Ascomycota (97% of all sequences). The most abundant Ascomycota classes included Sordariomycetes (77%), Dothideomycetes (21%), and Euromycetes (2%). Endophyte abundance was significantly greater in CAM vs. C3 bromeliads, but no differences were detected in terms of endophyte diversity. Endophyte community composition differed as a factor of host species, genus, and photosynthetic pathway. Differences in endophyte community composition among hosts suggest that bromeliads host unique and highly diverse endophyte communities. Current research is focused on relating endophyte community composition to leaf functional traits in tropical epiphytic bromeliads.