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
Designer cells: artificial enzyme can activate a gene switch
22.05.2018 | Universität Basel
Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
22.05.2018 | Trade Fair News
22.05.2018 | Trade Fair News
22.05.2018 | Life Sciences