Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


When plants bloom


New insights into the regulation of flowering: Besides light, temperature, age, and energy status, the soil nitrate level has an impact on the timing of flowering.

The regulation of flowering in plants is a highly complex process that is dependent on many internal and external factors. Flowering at the wrong time point leads to a loss of seed production and endangers the plant’s reproduction and survival of the species.

In contrast to low nitrogen soil (LN), plants are flowering early with optimal nitrogen supply (ON) with the help of the flowering regulator SOC1 that is produced in the shoot apex (yellow asterisk).

V. Wahl/ New Phytologist

To combat this problem, plants use a complex network of proteins to continuously monitor environmental factors, such as light and temperature, to determine the best time point for flowering. The work group of Dr. Vanessa Wahl from the Max Planck Institute of Molecular Plant Physiology, in cooperation with Dr. Anne Krapp from the National Institute for Agricultural Research (INRA) in Paris, have now revealed that nitrogen is involved in the regulation of the flowering time. In March, Dr. Wahl’s group published their exciting results in the scientific journal New Phytologist.

Nitrogen is one of the main nutrients required for plant growth, and is known to influence various developmental processes. Although our atmosphere is made up of 78% molecular nitrogen, this gaseous form cannot be used by plants. Instead, plants use their root systems to absorb nitrogen from the soil in the form of mineral compounds, such as ammonia or nitrate.

As plants grow, they gradually deplete nitrogen from the soil; therefore, nitrogen fertilizers have to be added to the soil to guarantee optimal plant growth and yield. If the amount of nitrogen in the soil exceeds the demand of the plant, or if nitrogen cannot be absorbed by roots due to environmental factors, such as drought, significant amounts of nitrogen are lost from the soil as run-off or leaching to groundwater, leading to environmental pollution. To avoid this scenario and promote sustainable agricultural practices, it is crucial that we gain a detailed knowledge of how nitrogen influences the plant’s life cycle, and use this information to direct and optimize fertilizer application practices.

After nitrogen absorbed by roots, it is transported through all plant organs by the vascular system. Nitrogen is used as a component in many important biological processes, such as amino acid and protein synthesis, and as part of the green pigment chlorophyll, which has an important role in photosynthesis. Plants grown in nitrogen-depleted soil experience chlorosis and a delay of growth, which directly results in a massive yield loss. In addition to being used as a nutrient, nitrate as the major form of nitrogen is also important as a signaling molecule. Dr. Vanessa Wahl explains her findings:

“In the model plant Arabidopsis thaliana, we showed that nitrogen is transported as nitrate into the shoot apical meristem (SAM) to influence flowering time. There, the protein SUPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) plays a crucial role as a central regulator of flowering at the SAM. SOC1 gene expression is activated by environmental signals like temperature and light, or by phytohormones. It is a so-called transcriptional activator, which can initiate the expression of other genes. As a result, SOC1 expression causes the plant to stop producing leaves and induces flowering.”

Her group’s experiments showed that the production of SOC1 is nitrate-dependent. As proof, plants were grown on nitrogen-limited soil and compared to plants grown on full-nutrition soil. Dr. Vanessa Wahl explains: “The higher the nitrate level of the soil, the more SOC1 was produced, causing plants to flower earlier. Conversely, under nitrogen-limitation, flowering was delayed”. In addition, nitrate responsive elements (NREs) were identified in many genes already known to be involved in the regulation of SOC1 and flowering time. Nitrate can activate these genes, which subsequently explains the elevated level of SOC1. Finally, it was shown for the first time that nitrate is transported into the SAM where it can be metabolized to ammonia. This conversion is mediated by nitrate reductase, found to be present in the SAM. The tissue-specific expression of nitrate reductases was published in the journal Signaling & Behavior in August.

Because flowering is an energy-consuming process, the time point of flowering also depends on the availability of sugars, which act as the plant’s energy source. In this respect, Dr. Vanessa Wahl showed that the sugar trehalose 6-phosphate (T6P) plays an important role in flowering, as published by her group in the journal Science (2013). Interestingly, flowering initiation is signaled by T6P and nitrate independent from each other. If both signals are inhibited flowering is not induced.

In summary, plants are able to adapt their life cycles depending on the availability of nitrogen by delaying their flowering time, due to suboptimal growth conditions. Deeper knowledge about the interplay of nitrogen and sugar sensing in terms of flowering time will help to develop new strategies to increase the yield of crops when grown on nitrogen-limited soil. By understanding these biological processes, we stand to gain an important approach to optimizing the use and application of nitrogen fertilizer.

Wissenschaftliche Ansprechpartner:

Dr. Vanessa Wahl
Am Mühlenberg 1, 14476 Potsdam
Tel.:+49 331 4567-8116


Weitere Informationen:

Dipl. Ing. agr. Ursula Ross-Stitt | Max-Planck-Institut für Molekulare Pflanzenphysiologie
Further information:

More articles from Life Sciences:

nachricht New portable tool analyzes microbes in the environment
27.01.2020 | Rutgers University

nachricht Cucumber, courgette and pumpkin under threat – first evidence of cucumber virus in Germany
27.01.2020 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Integrate Micro Chips for electronic Skin

Researchers from Dresden and Osaka present the first fully integrated flexible electronics made of magnetic sensors and organic circuits which opens the path towards the development of electronic skin.

Human skin is a fascinating and multifunctional organ with unique properties originating from its flexible and compliant nature. It allows for interfacing with...

Im Focus: Dresden researchers discover resistance mechanism in aggressive cancer

Protease blocks guardian function against uncontrolled cell division

Researchers of the Carl Gustav Carus University Hospital Dresden at the National Center for Tumor Diseases Dresden (NCT/UCC), together with an international...

Im Focus: New roles found for Huntington's disease protein

Crucial role in synapse formation could be new avenue toward treatment

A Duke University research team has identified a new function of a gene called huntingtin, a mutation of which underlies the progressive neurodegenerative...

Im Focus: A new look at 'strange metals'

For years, a new synthesis method has been developed at TU Wien (Vienna) to unlock the secrets of "strange metals". Now a breakthrough has been achieved. The results have been published in "Science".

Superconductors allow electrical current to flow without any resistance - but only below a certain critical temperature. Many materials have to be cooled down...

Im Focus: Programmable nests for cells

KIT researchers develop novel composites of DNA, silica particles, and carbon nanotubes -- Properties can be tailored to various applications

Using DNA, smallest silica particles, and carbon nanotubes, researchers of Karlsruhe Institute of Technology (KIT) developed novel programmable materials....

All Focus news of the innovation-report >>>



Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

Latest News

Dance of the honey bee reveals fondness for strawberries

27.01.2020 | Agricultural and Forestry Science

MTU engineers examine lithium battery defects

27.01.2020 | Power and Electrical Engineering

Quantum physics: On the way to quantum networks

27.01.2020 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>