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Güngör E, Savary J, Adema K, Dijkhuizen LW, Keilwagen J, Himmelbach A, Mascher M, Koppers N, Bräutigam A, Van Hove C, Riant O, Nierzwicki-Bauer S, Schluepmann H. The crane fly glycosylated triketide δ-lactone cornicinine elicits akinete differentiation of the cyanobiont in aquatic Azolla fern symbioses. Plant Cell Environ 2024. [PMID: 38600764 DOI: 10.1111/pce.14907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/02/2024] [Accepted: 03/22/2024] [Indexed: 04/12/2024]
Abstract
The restriction of plant-symbiont dinitrogen fixation by an insect semiochemical had not been previously described. Here we report on a glycosylated triketide δ-lactone from Nephrotoma cornicina crane flies, cornicinine, that causes chlorosis in the floating-fern symbioses from the genus Azolla. Only the glycosylated trans-A form of chemically synthesized cornicinine was active: 500 nM cornicinine in the growth medium turned all cyanobacterial filaments from Nostoc azollae inside the host leaf-cavities into akinetes typically secreting CTB-bacteriocins. Cornicinine further inhibited akinete germination in Azolla sporelings, precluding re-establishment of the symbiosis during sexual reproduction. It did not impact development of the plant Arabidopsis thaliana or several free-living cyanobacteria from the genera Anabaena or Nostoc but affected the fern host without cyanobiont. Fern-host mRNA sequencing from isolated leaf cavities confirmed high NH4-assimilation and proanthocyanidin biosynthesis in this trichome-rich tissue. After cornicinine treatment, it revealed activation of Cullin-RING ubiquitin-ligase-pathways, known to mediate metabolite signaling and plant elicitation consistent with the chlorosis phenotype, and increased JA-oxidase, sulfate transport and exosome formation. The work begins to uncover molecular mechanisms of cyanobiont differentiation in a seed-free plant symbiosis important for wetland ecology or circular crop-production today, that once caused massive CO2 draw-down during the Eocene geological past.
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Affiliation(s)
- Erbil Güngör
- Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Jérôme Savary
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Kelvin Adema
- Department of Biology, Utrecht University, Utrecht, The Netherlands
| | | | | | - Axel Himmelbach
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Seeland, Germany
| | - Martin Mascher
- Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Seeland, Germany
| | - Nils Koppers
- Computational Biology, Center for Biotechnology and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Andrea Bräutigam
- Computational Biology, Center for Biotechnology and Faculty of Biology, Bielefeld University, Bielefeld, Germany
| | - Charles Van Hove
- Emeritus Professor from the Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Olivier Riant
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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