Hunters or gardeners? Linking community structure and function of trap-associated microbes to the nutrient acquisition strategy of a carnivorous plant

All higher eukaryotes live in a relationship with diverse microorganisms which colonize their bodily surfaces; plants are no exception. However, we still lack a satisfactory understanding of how these loosely associated microbiomes with immense diversity and functional potential interact with their hosts or how these interactions shape processes within populations and ecosystems. There is considerable similarity between microbial communities colonizing plant surfaces such as roots, and those of the animal gut. This often overlooked parallel allows us to look at microbial as well as host ecophysiology from a fresh perspective. The traps of carnivorous plants are sophisticated digestive organs and interface environments between the supply and the demand for nutrients. We selected the miniature ecosystem in the traps of aquatic carnivorousUtriculariaplants as our model system. By assessing the trap-associated microbial community structure, diversity, function, as well as the nutrient recycling potential of bacterivory, we gained insight into the nutrient acquisition strategies of theUtriculariahosts. We conclude that trap ecophysiological function is in many aspects highly analogous to that of the herbivore gut and centers around complex microbial consortia, which act synergistically to covert complex organic matter, often of algal origin, into a source of nutrients for the plants.