ERP009076 PRJEB8041 ena-STUDY-Barta-18-12-2014-10:51:22:876-169 Hunters or gardeners Probing plant–microbe interactions in rootless carnivorous Utricularia from a transcriptomic perspective The rootless genus Utricularia (Lentibulariaceae) is the most cosmopolitan and successful genus of carnivorous plants, with terminal position in the phylogeny of eudicots. Especially aquatic Utricularia species represent a unique model system to study plant–microbe interactions and their role in plant nutrition and ecophysiology. The trapping organs, characteristic for the genus, are small hollow utricles filled with fluid and heavily colonized by microorganisms. The trap lumen is under anoxic conditions interrupted by very short periods of usable, non-zero oxygen concentrations after firing events. Preliminary results show that the microbial community inhabiting the trap interior is not represented by species unique or especially adapted for this association, but rather that microorganisms are recruited from the ambient water column and periphyton. Due to the fast apical growth of the plants, the traps undergo rapid development and ageing. Completely sealed from the outside environment, except for firing events, the lumen of a trap contains a fully functional and complex microbial loop adapted to the current, but permanently changing conditions in the environment, including the changing nutrient supply. Considerable concentrations of C, N and P (up to three orders of magnitude higher than in the ambient water) were found in preyless traps in two Utricularia species. A single plant may have hundreds to thousands of traps with very large inner absorption surfaces. Taking further into account the large metabolic potential of associated bacteria and the great transporting capacity of abundant quadrifid secretory/absorptive glands inside traps, the benefits of this plant–microbe association for the plants become obvious. Its importance is further underscored by the fact that Utricularia supply as much as 20–25% of newly photosynthetically fixed carbon into the trap fluid, mainly in younger traps. We would like to take advantage of recent advances in high-throughput sequencing, which now allow us to compare entire transcriptomes from different Utricularia tissues or plants. We believe that the analysis of genome-wide differential RNA expression will allow us to address questions arising from our central hypothesis and provide us with greater insights into biological pathways and molecular mechanisms that underlie the plant–microbe association. Sequence data will therefore constitute the central part of our project, supported by data from growth experiments, stable isotope and nutrient analyses. Hunters or gardeners The rootless genus Utricularia (Lentibulariaceae) is the most cosmopolitan and successful genus of carnivorous plants, with terminal position in the phylogeny of eudicots. Especially aquatic Utricularia species represent a unique model system to study plant–microbe interactions and their role in plant nutrition and ecophysiology. The trapping organs, characteristic for the genus, are small hollow utricles filled with fluid and heavily colonized by microorganisms. The trap lumen is under anoxic conditions interrupted by very short periods of usable, non-zero oxygen concentrations after firing events. Preliminary results show that the microbial community inhabiting the trap interior is not represented by species unique or especially adapted for this association, but rather that microorganisms are recruited from the ambient water column and periphyton. Due to the fast apical growth of the plants, the traps undergo rapid development and ageing. Completely sealed from the outside environment, except for firing events, the lumen of a trap contains a fully functional and complex microbial loop adapted to the current, but permanently changing conditions in the environment, including the changing nutrient supply. Considerable concentrations of C, N and P (up to three orders of magnitude higher than in the ambient water) were found in preyless traps in two Utricularia species. A single plant may have hundreds to thousands of traps with very large inner absorption surfaces. Taking further into account the large metabolic potential of associated bacteria and the great transporting capacity of abundant quadrifid secretory/absorptive glands inside traps, the benefits of this plant–microbe association for the plants become obvious. Its importance is further underscored by the fact that Utricularia supply as much as 20–25% of newly photosynthetically fixed carbon into the trap fluid, mainly in younger traps. We would like to take advantage of recent advances in high-throughput sequencing, which now allow us to compare entire transcriptomes from different Utricularia tissues or plants. We believe that the analysis of genome-wide differential RNA expression will allow us to address questions arising from our central hypothesis and provide us with greater insights into biological pathways and molecular mechanisms that underlie the plant–microbe association. Sequence data will therefore constitute the central part of our project, supported by data from growth experiments, stable isotope and nutrient analyses.