Too early or too late blooming can have serious consequences for plants: It may reduce the crop of seeds and jeopardize the reproductive success of an entire season. In order not to miss the exact time of flowering, plants have therefore evolved an extensive control system that involves several dozen genes.
The thale cress, Arabidopsis thaliana, regulates its flowering time in response to temperature. Left: 27 C; centre: 23 C, right: 16 C.
© MPI for Developmental Biology/Schmid
Arabidopsis flowers at various temperatures at various times (left: 16 C, right: 23 C).
© MPI for Developmental Biology/Schmid
Under the leadership of Markus Schmid, molecular geneticist at the Max Planck Institute for Developmental Biology in Tübingen, and in collaboration with the group of Richard Immink, part of Wageningen UR, at Plant Research International in the Netherlands, an international team of researchers has studied two key genes that regulate flowering time in response to ambient temperature. According to their report in the current issue of Nature magazine online, they uncovered a clever molecular mechanism.
Many genes involved in the control of flowering time had already been known from previous studies on the plant Arabidopsis thaliana. "The genetic network integrates the hormonal status as well as external factors such as day length or temperature", says project leader Schmid. There is still very limited knowledge about the molecular mechanisms by which the ambient temperature influences the flowering decision. The research team therefore focused on two genes, FLM (FLOWERING LOCUS M) and SVP (SHORT VEGETATIVE PHASE), which had already been attributed a key role in this process.
As the researchers were able to show, the FLM gene can give rise to several different protein variants by a process called alternative splicing: After an mRNA copy of the gene has been produced, this pre-mRNA is not directly translated into protein; instead, one or several pieces are cut out - or spliced out as geneticists put it. In genes subject to alternative splicing, this can be done in different ways, producing different mature mRNA-molecules and finally various proteins.
In the case of the Arabidopsis FLM gene there are mainly two splice products, referred to as FLM-β and FLM-δ. A The Tübingen experiments have demonstrated that FLM-activity at low temperatures results mainly in the production of FLM-β. As temperature rises, levels of FLM-β gradually decrease in favour of the expression of FLM-δ. "We observed that this process adapts quite rapidly to temperature changes", says David Posé, first author of the study. "When heated from 16 °C to 27 °C, the ratio of FLM-variants adjusts within 24 hours."
Schmid and his colleagues carried out extensive binding studies and found that FLM-β forms a functional protein complex with SVP that can effectively attach to genomic DNA. The binding sites are located mainly within the regulatory regions of genes involved in flowering time and floral patterning. "The SVP-FLM-β complex acts as a potent repressor that prevents the formation of flowers", explains Prof. Immink, who has specialized in floral induction. The closely related complex consisting of SVP and the "heat indicator" FLM-δ, however, is hardly able to attach to DNA. As a result, the flowering genes are released from repression, become active and promote flower transition.
The international research team is impressed with the elegance and efficiency of this regulatory mechanism. Project leader Schmid analyzes that "instead of tackling the problem with two genes, one of which promotes flowering while the other suppresses it, the plants have combined the two conflicting functions in a single gene." This results in a dual regulation: With increasing temperatures, the flowering repressor FLM-β is not only produced at a slower rate - it also has to compete for SVP-binding with its own sister-protein, FLM-δ.
Naturally occurring strains of Arabidopsis can differ substantially with respect to their flowering times, and this difference is partly due to the natural variation of the FLM gene. As this variation presumably helps plants cope with differences in growth conditions in different habitats, it could also enable them to adapt to the gradual warming that is expected as a result of global climate change. For Schmid and his colleagues there is no doubt that the newly discovered mechanism will be important, especially for plants that cannot move to cooler habitats. "The role of temperature-dependent alternative splicing in this adaptation process is well worthy of further investigation", the researchers conclude.
ContactProf. Dr. Markus Schmid
Nadja Winter | Max-Planck-Institute
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences