Flowering time regulation in Beta species
The transition from vegetative to generative growth in the lifetime of a flowering plant is triggered by a number of genes together with endogenous stimuli as well as environmental cues, such as temperature or day length changes. To ensure optimal reproductive success, flowering plants have developed different life cycles. Sugar beet (Beta vulgaris) is a biennial root crop that grows vegetatively in the first year and starts shoot elongation (bolting) and flowering after exposure to cold temperatures (vernalization) after winter. The BOLTING TIME CONTROL 1 (BTC1) gene at the bolting locus B was discovered to control annuality (bolting without vernalization) through regulation of the two beet FT homologs BvFT1 and BvFT2.
Besides BTC1, additional bolting loci have been identified among the offspring of an ethylmethanesulfonate (EMS) mutagenized annual beet accession carrying the dominant BTC1 allele. Apart from BTC1, we have identified and functionally characterized the bolting time gene BvBBX19 by a map-based cloning approach.
We aim to understand life cycle adaption in context with the genetic network that regulates floral transition in sugar beet, with the long-term objective of providing a tool kit for targeted modification of bolting and flowering time. Applications in plant breeding include suppression of vernalization-responsiveness to enable winter cultivation and marker-assisted selection for synchronization of flowering time for hybrid seed production, as well as understanding and expanding the evolutionary relationship of flowering time pathways between Beta and other species.
BvBBX19 acts together with BTC1 to induce bolting and flowering in beet. Functional analyses of BvBBX19 as well as the genetic mapping of the bolting locus B5 are currently in progress. We developed a F2 population that segregates for BTC1 and BvBBX19. The F2 population was phenotyped under controlled conditions in a climate chamber for bolting before and after cold treatment. In order to measure the effect of different BTC1 and BvBBX19 allele combinations on the expression of the floral activator BvFT2 we are currently analyzing all F2 genotypes. In parallel, we have transformed Arabidopsis wildtype and mutant plants with BTC1 and BvBBX19 that will be phenotyped for flowering time in future. In collaboration with other partners in the frame of the DFG priority program 1530 (www.flowercrop.uni-kiel.de), we are currently analyzing the interaction of the two proteins in vivo. Additionally, phenotyping of plants from a diverse Beta panel revealed a correlation between the geographical origin of an accession and its bolting behavior. Haplotype analyses of BvBBX19, BTC1, BvFT1 and BvFT2 revealed genomic changes over a latitudinal gradient reflecting the domestication process of cultivated sugar beet.
Dr. Daniela Holtgräwe (CeBiTec, University of Bielefeld, Germany)
Prof. Dr. Bernd Weisshaar (Chair of Genome Research, University of Bielefeld, Germany)
Prof. Dr. George Coupland, Max Planck Institute for Plant Breeding Research, Cologne, Germany
Prof. Dr. Alfred Batschauer, Molecular Plant Physiology and Photobiology, Philipps-University Marburg, Marburg, Germany
Blümel, M., N. Dally, Jung, C. (2015) Flowering time regulation in crops-what did we learn from Arabidopsis? Current Opinion in Biotechnology 32C: 121-129.
Dally, N. (2015) Identification of the transcription factor BvBBX19 and its role in flowering time control in beet. 17. Kurt von Rümker-Vorträge 85: 19-26.
Dally, N., Xiao, K., Holtgräwe, D., Jung, C. (2014) The B2 flowering time locus of beet encodes a zinc finger transcription factor. Proceedings of the National Academy of Sciences of the United States of America 111(28): 10365-10370.
Pin, P. A., Zhang, W., Vogt, S. H., Dally, N., Büttner, B., Schulze-Buxloh, G., Jelly, N. S., Chia, T. Y. P., Mutasa-Göttgens, E. S., Dohm, J. C., Himmelbauer, H., Weisshaar, B., Kraus, J., Gielen, J. J. L., Lommel, M., Weyens, G., Wahl, B., Schechert, A., Nilsson, O., Jung, C., Kraft, T., Müller, A. E. (2012) The role of a pseudo-response regulator gene in lifecycle adaptation and domestication of beet. Current Biology 22:1095-1101.
Büttner, B., Abou-Elwafa, S. F., Zhang, W., Jung, C. and Müller, A (2010) A survey of EMS-induced biennial Beta vulgaris mutants reveals a novel bolting locus which is unlinked to the bolting gene B. Theoretical and Applied Genetics 121:1117-1131.
Posters and Oral Presentations
Dally N., Eckel M., Batschauer A., Jung C. (2016) Characterization of Two Key Regulators Controlling Bolting Time in Beta Species Reveals a Novel Mechanism for Floral Transition in Beet, Euro Plant Biology 2016 (EPSO), Prague, 26-30.06.2016, Oral Presentation.
Höft N., Dally N., Jung C. (2016) The Impact of Geographical Origin of Beta Species on its Different Life Cycle Regimes, Flower Crop-SPP1530 Workshop on circadian rhythms, Berlin 20.-22.01.2016, Oral Presentation.
Dally N., Eckel M., Höft N., Batschauer A., Jung C. (2016) Functional analysis of two key regulators for bolting time in Beta species to breed winter sugar beets“, Flower Crop-SPP1530 Workshop on circadian rhythms, Berlin 20.-22.01.2016, Poster Presentation.
Höft N., Dally N., Jung C. (2015) Unravelling the Origin of the Crop Sugar Beet: Towards Understanding the Evolution of different Life Cycle Regimes in Beta Species, IPMB 2015: 11th Congress of International Plant Molecular Biology (IPMB), Iguazú Falls, Brazil, 25. – 30.10.2015, Poster Presentation.
Höft, N., Dally, N., Jung C. (2014) Life cycle adaption in beet - identification of a new bolting time gene. GPZ 2014: Genetic Variation in Plant Breeding, University Kiel 23.-25.09.2014. Poster Presentation.
Höft, N., Dally, N., Jung C. (2014) Functional characterization of a new bolting time gene from sugar beet. II. International Symposium: Genetic Variation of Flowering Time Genes and Applications for Crop Improvement, University Bielefeld 24.-26.03.2014. Poster Presentation.
Höft, N., Tränkner C., Jung C., Melzer S. (2012) Control of flowering in sugar beet and Arabidopsis through activation of flowering time repressors by FLP-FRT recombination. "Breeding crops for sustainable agricultural production" Symposium of GPZ e.V., Gießen 28.2.-1.3.2012. Poster Presentation.
Funding has been provided by the Deutsche Forschungsgemeinschaft under grant No. DFG JU 205/24-1 and the International Max Planck Research School for Evolutionary Biology, Plön/Kiel.
Updated: 11-Aug-16 Responsible for this webpage: Dr. Nadine Dally, M.Sc. Nadine Höft