Vienna, Austria
July 14, 2014
Teamwork: Wolfram Weckwerth, Jürg Schönbergerer, Yannick Städler and Anke Bellaire (left to right).
Developmental processes in all living organisms are controlled by genes. At the same time there is a continuous metabolism taking place. Wolfram Weckwerth, head of the Department of Ecogenomics and Systems Biology at University of Vienna, and his team have analyzed this interaction between metabolism and developmental processes in flowering plants (angiosperms). Angiosperms, with more than 300.000 species, are an important group of plants as they are on one hand the foundation of our nutrition in form of fruit, vegetable and grain and on the other hand contributing significantly to the biodiversity of ecosystems. In a recent study on flower development, changes in metabolism were linked to three-dimensional morphometric data using micro-computed tomography (micro-CT) for the first time.
Inflorescence of Arabidopsis thaliana.
In close collaboration with Jürg Schönenberger and Yannick Städler from the Department of Botany and Biodiversity Research of the Faculty of Life Sciences, University of Vienna, 14 developmental stages of the flower of Arabidopsis thaliana from very early meristematic floral initiation to fully developed seeds were monitored with micro-computed tomography in 3D. From the same set of developmental stages a full metabolic profile using mass spectrometry was measured covering hundreds of biochemical pathways.
3D image of a fully developed flower of Arabidopsis thaliana was added with a micro-computer tomography. In the ovary, the ovules are clearly visible. The strongly contrasting pollen grains are released from the anthers.
"Smallest changes in floral organ development were thus correlated with distinct metabolic profiles, and remarkable differences in metabolism were detected over the full development", says Wolfram Weckwerth. Based on these data it is possible to define the interaction of developmental processes and metabolism in a hitherto unreached resolution. Thus, the integration of 3D data of developmental processes with metabolic activities opens up a new avenue of research in developmental biology.
Development, Sex and Metabolism
Flower development finds its fulfillment in the fusion of egg cell (ovule) and spermium. The ovule is immovable and safely protected inside the ovary whereas the spermium is mobile and transported via pollen to the female sexual organ. During fertilization the sperm cell makes its way through the elongated pollen tube towards the ovule deep inside the flower. After successful fusion a tiny embryo develops – which can be found in every plant seed.
The pollinated and fertilized flower develops into a fruit. Above: pods of Arabidopsis thaliana after 27 days flower development. Below: A dicotyledonous embryo (E) in its seed, which is surrounded by the pod wall (upper and lower capped tissue).
Whether fertilization is successful relies on the correct timing of the metabolism. It is metabolism that provides all the energy and biomass resources for the developmental processes. Throughout these processes the metabolic activities of the various developmental stages undergo dramatic changes: In the beginning a high activity of disaccharides and amino acid metabolism can be observed whereas in later stages when the sexual organs become mature monosaccharides, organic acids and different amino acids accumulate. The mature seed, finally, shows a complete different metabolic profile compared to the former ones. "There are specific metabolic signatures which represent the distinct developmental processes of all organs from early flower until fully developed fruit and seed", describes Anke Bellaire, first author of the study.
Future studies will analyze the flower development in other angiosperms lineages to reveal each specific ontogenetic signature / trajectory of the combined metabolic and morphometric profile. Based on these detailed observations generic principles of the interaction of metabolism and development will be identified.
Publication in "New Phytologist":
Anke Bellaire, Till Ischebeck, Yannick Staedler, Isabell Weinhaeuser, Andrea Mair, Sriram Parameswaran, Toshiro Ito, Jürg Schönenberger and Wolfram Weckwerth:
Metabolism and development – integration of micro computed tomography data and metabolite profiling reveals metabolic reprogramming from floral initiation to silique development.
In: New Phytologist (2014) 202: 322–335
DOI: 10.1111/nph.12631
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