Relationships between Foliar Fungal Endophyte Communities and Ecophysiological Traits of CAM and C3 Epiphytic Bromeliads in a Neotropical Rainforest

Peter H Tellez,Sunshine A Van Bael,Carrie L Woods,Stephen Formel

doi:10.3390/d12100378

Peter H Tellez, Sunshine A Van Bael + Show 2 more

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https://doi.org/10.3390/d12100378

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Abstract

Vascular epiphytes contribute up to 35% of the plant diversity and foliar biomass of flowering plants. The family Bromeliaceae is a monophyletic group of plants native to the Neotropics. Epiphytic bromeliads form associations with distinct groups of organisms but their relationship with foliar fungal endophytes remain underexplored. In this study we examined the relationship of foliar fungal endophytes to host photosynthetic pathways and associated ecophysiological traits. We sampled the fungal endophyte communities of 67 host individuals in six epiphytic bromeliad species differing in C3 and crassulacean acid metabolism (CAM) photosynthetic pathways. We tested whether endophyte assemblages were associated with ecophysiological leaf traits related to host photosynthetic pathways. Our results indicate that (1) C3 and CAM bromeliads host dissimilar endophyte assemblages, (2) endophyte communities in C3 bromeliads are characterized by variable relative abundances of fungal orders; conversely, CAM associated endophyte communities were characterized by consistent relative abundances of fungal orders, and (3) endophyte communities in bromeliads are distributed along a continuum of leaf toughness and leaf water content. Taken together, our study suggests that host physiology and associated ecophysiological traits of epiphytic bromeliads may represent biotic filters for communities of fungal endophytes in the tropics.

Highlights

Often overlooked, vascular epiphytes are a distinctive and integral component of tropical forests, contributing between 25% and 35% of plant diversity [1] and up to 35% of the biomass of flowering plants [2]
We examine the associations of foliar fungal endophyte communities to photosynthetic pathways and related ecophysiological leaf traits of six common epiphytic bromeliads in a tropical wet rainforest in Costa Rica
Within the phylum Ascomycota, which generally make up the foliar communities in tropical plants, we found that the classes Sordariomycetes comprised 95.4% of the foliar communities, while the highest classes constituted Dothideomycetes, Arthoniomycetes, and Saccharomycetes (3.71%)

Summary

Introduction

Vascular epiphytes are a distinctive and integral component of tropical forests, contributing between 25% and 35% of plant diversity [1] and up to 35% of the biomass of flowering plants [2]. Vascular epiphytes include major taxonomic groups such as orchids, ferns, aroids, and bromeliads [3]. Tropical bromeliads frequently form associations with an abundant and diverse group of microsymbionts. These can include, algae [6], freshwater protozoa [7], yeasts [8], phyllosphere bacteria [9], and arbuscular mycorrhizal fungi [10,11]. Because of their cryptic nature, foliar fungal

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