Symbiosis; Burkholderia; Plant-microbe interaction; Plant genomics; Organic synthesis; Chemical ecology; Comparative genomics; Chemical biology; Psychotria; Aminocyclitol
Hsiao Chien-Chi, Sieber Simon, Georgiou Antri, Bailly Aurélien, Emmanouilidou Despina, Carlier Aurélien, Eberl Leo, Gademann Karl (2019), Synthesis and Biological Evaluation of the Novel Growth Inhibitor Streptol Glucoside, Isolated from an Obligate Plant Symbiont, in
Chemistry - A European Journal, 25(7), 1722-1726.
Gademann Karl, Eberl Leo, Carlier Aurelien, Pinto-Carbó Marta (2018), Leaf nodule symbiosis: function and transmission of obligate bacterial endophytes, in
Current Opinion in Plant Biology, 44, 23-31.
Reher R, Schamari I, Kehraus S, Annala S, Kuschak M, Schäberle T, Crüsemann M, Carlier A, Eberl L, Müller CE, Kostenis E, König GM (2016), The endophyte Candidatus Burkholderia crenata of the TCM plant Ardisia crenata produces the selective Gq-inhibitor FR900359, in
Planta Medica, 81(S 01), S1-S381.
Carlier Aurelien, Fehr Linda, Pinto-Carbó Marta, Schäberle Till, Reher Raphael, Dessein Steven, König Gabriele, Eberl Leo (2016), The genome analysis of Candidatus Burkholderia crenata reveals that secondary metabolism may be a key function of the Ardisia crenata leaf nodule symbiosis Ca . B. crenata genome, in
Environmental Microbiology, 18(8), 2507-2522.
Pinto-Carbó Marta, Sieber Simon, Dessein Steven, Wicker Thomas, Verstraete Brecht, Gademann Karl, Eberl Leo, Carlier Aurelien (2016), Evidence of horizontal gene transfer between obligate leaf nodule symbionts, in
The ISME Journal, 10(9), 2092-2105.
Reher R, Schamari I, Kehraus S, Annala S, Kuschak M, Schäberle T, Crüsemann M, Carlier A, Eberl L, Müller C E, Kostenis E, König G M (2016), The endophyte Candidatus Burkholderia crenata of the TCM plant Ardisia crenata produces the selective Gq-inhibitor FR900359., in
The endophyte Candidatus Burkholderia crenata of the TCM plant Ardisia crenata produces the selectiv, Planta Medica, Georg Thieme Verlag KG Stuttgart · New York.
Carlier Aurelien, Gademann Karl, Sieber Simon, Neuburger Markus, Grabenweger Giselher, Eberl Leo (2015), Isolation and Total Synthesis of Kirkamide, an Aminocyclitol from an Obligate Leaf Nodule Symbiont, in
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, (27), 7968-7970.
Carlier Aurelien (2015), The genome analysis of Candidatus Burkholderia crenata reveals that secondary metabolism may be a key function of the Ardisia crenata leaf nodule symbiosis, in
Environ Microbiol., 13184.
Symbioses between prokaryotes and eukaryotes are very common and are known from many animal phyla, including insects, nematodes, sponges, annelids, mollusks and bryozoans. While some associations are facultative others are highly specific and perpetual. The application of molecular and more recently of next generation sequencing technologies led to the identification of many symbioses that are obligate, at least from the host perspective. In these cases the bacterial symbionts are essential for host development and reproduction; they are usually transmitted maternally, are often unable to proliferate outside of the host, frequently provide the host with nutrients, and are sometimes restricted to a specialized organ within the host. In stark contrast to animals, only two symbioses have been described for plants in which the bacteria are vertically transmitted. One is the association of cyanobacteria and the water fern Azolla sp., where the colonizing cyanobionts fix atmospheric nitrogen and release nitrogen-rich metabolites into the leaf cavity. Although the bacteria are transmitted between the plant generations, Azolla can survive without its symbiont. The other plant-bacterium association is the bacterial plant leaf symbiosis, which is obligate for both partners and was described by Zimmermann already in 1902. Evidence that has accumulated since then has demonstrated that leaf nodules represent the arguably most complex, and certainly most intimate associations between bacteria and higher plants, as neither the host nor the bacterial symbiont can exist outside the symbiosis. In spite of more than a century of research, the reasons for the strict interdependence of this plant-bacterium association are unknown. In an interdisciplinary approach, involving three groups with complementary expertise in microbiology (Eberl/Carlier, UZH), chemistry (Gademann, UniBas) and plant biology (Wicker, UZH) the proposed Sinergia project aims at unraveling the molecular basis of this unique symbiosis. Our preliminary data indicate that the bacterial symbiont is involved in the biosynthesis of a novel C7N aminocyclitol (Eberl/Carlier), the structure of which was determined by the Gademann group. Given that compounds of the C7N aminocyclitol family display various biological activities, often inhibiting glycosidases, we hypothesize that kirkamide is central to the symbiosis. In this project, we intend to demonstrate that leaf nodule bacteria are directly responsible for kirkamide biosynthesis (Eberl/Carlier). We want to chemically synthesize kirkamide (Gademann) and investigate its biological effects, notably on plant growth and development using RNA-Seq (Wicker). In a collaborative effort of the three groups we want to unravel the biosynthetic pathway of kirkamide and reconstitute it in a heterologous host (Eberl/Carlier) that will be used in attempts to replace the bacterial symbiont. We will look for evidence of co-evolution of the symbiotic partners by sequencing respective genomes to investigate whether the symbionts are strictly vertically transmitted or host switching occurs (Eberl/Carlier & Wicker). The plant genome data will also form the basis for a bioinformatic-guided identification of putative kirkamide targets in the plant (Wicker & Gademann), which will be validated by appropriate bioassays. The results of this project are expected to not only reveal fundamental insights into the only known obligate bacterium-plant symbiosis but may also lead to novel biotechnological applications.