Hunters or farmers? Microbiome characteristics help elucidate the diet composition in an aquatic carnivorous plant

Dagmara Sirová,Jakub Borovec,James Stone,Thomas Posch,Jaroslav Vrba,Lubomír Adamec,Jiří Bárta,Jiří Pech,Karel Šimek

doi:10.1186/s40168-018-0600-7

Abstract

BackgroundUtricularia are rootless aquatic carnivorous plants which have recently attracted the attention of researchers due to the peculiarities of their miniaturized genomes. Here, we focus on a novel aspect of Utricularia ecophysiology—the interactions with and within the complex communities of microorganisms colonizing their traps and external surfaces.ResultsBacteria, fungi, algae, and protozoa inhabit the miniature ecosystem of the Utricularia trap lumen and are involved in the regeneration of nutrients from complex organic matter. By combining molecular methods, microscopy, and other approaches to assess the trap-associated microbial community structure, diversity, function, as well as the nutrient turn-over potential of bacterivory, we gained insight into the nutrient acquisition strategies of the Utricularia hosts.ConclusionsWe conclude that Utricularia traps can, in terms of their ecophysiological function, be compared to microbial cultivators or farms, which center around complex microbial consortia acting synergistically to convert complex organic matter, often of algal origin, into a source of utilizable nutrients for the plants.

Highlights

Utricularia are rootless aquatic carnivorous plants which have recently attracted the attention of researchers due to the peculiarities of their miniaturized genomes
We present the results of the trap microbiome sequencing, distinguishing between the inner and periphytic communities associated with two Utricularia species—U. australis and U. vulgaris
Unique trap-associated prokaryotic communities Our results show that Utricularia plants harbor surprisingly diverse microbial communities: we have identified over 4500 distinct prokaryotic OTUs in the traps and periphyton

Summary

Introduction

Utricularia are rootless aquatic carnivorous plants which have recently attracted the attention of researchers due to the peculiarities of their miniaturized genomes. Apart from the well-studied and close symbioses such as mycorrhizal and rhizobial interactions, there is a large pool of diverse microorganisms in varying degrees of association with different plant surfaces and tissues Depending on the species and growth conditions, a single Utricularia plant may bear hundreds to thousands of traps, usually on highly segmented leaves (Additional file 1: Figure S1). These are tiny (1–5 mm long) liquid-filled bladders, whose lumen is completely isolated from the environment by a two-cell thick trap wall [12]. Short bursts of oxygenated water from the outside transiently improve the oxygen conditions each time the trap fires [13]

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Results

Conclusion