Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When plants bloom

29.11.2019

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
Email: VWahl@mpimp-golm.mpg.de

Originalpublikation:

https://doi.org/10.1111/nph.15812

Weitere Informationen:

https://doi.org/10.1080/15592324.2019.1656035
https://science.sciencemag.org/content/339/6120/704.full

Dipl. Ing. agr. Ursula Ross-Stitt | Max-Planck-Institut für Molekulare Pflanzenphysiologie
Further information:
http://www.mpimp-golm.mpg.de

More articles from Life Sciences:

nachricht Fight diabetes with exercise
29.11.2019 | Leibniz-Institut für Naturstoff-Forschung und Infektionsbiologie - Hans-Knöll-Institut (HKI)

nachricht Harnessing the power of CRISPR in space and time
29.11.2019 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften 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: How do scars form? Fascia function as a repository of mobile scar tissue

Abnormal scarring is a serious threat resulting in non-healing chronic wounds or fibrosis. Scars form when fibroblasts, a type of cell of connective tissue, reach wounded skin and deposit plugs of extracellular matrix. Until today, the question about the exact anatomical origin of these fibroblasts has not been answered. In order to find potential ways of influencing the scarring process, the team of Dr. Yuval Rinkevich, Group Leader for Regenerative Biology at the Institute of Lung Biology and Disease at Helmholtz Zentrum München, aimed to finally find an answer. As it was already known that all scars derive from a fibroblast lineage expressing the Engrailed-1 gene - a lineage not only present in skin, but also in fascia - the researchers intentionally tried to understand whether or not fascia might be the origin of fibroblasts.

Fibroblasts kit - ready to heal wounds

Im Focus: McMaster researcher warns plastic pollution in Great Lakes growing concern to ecosystem

Research from a leading international expert on the health of the Great Lakes suggests that the growing intensity and scale of pollution from plastics poses serious risks to human health and will continue to have profound consequences on the ecosystem.

In an article published this month in the Journal of Waste Resources and Recycling, Gail Krantzberg, a professor in the Booth School of Engineering Practice...

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Engineers at Duke University have developed a microscope that adapts its lighting angles, colors and patterns while teaching itself the optimal...

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...

Im Focus: Atoms don't like jumping rope

Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.

By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

Harnessing the power of CRISPR in space and time

29.11.2019 | Life Sciences

When plants bloom

29.11.2019 | Life Sciences

New evolutionary insights into the early development of songbirds

29.11.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>