Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Red Light Regulates Nectar Secretion

27.09.2010
Nectar production in Lima beans depends on light quality

Flowering plants produce nectar to attract insect pollinators. Some plant species, such as Lima bean, also secrete nectar from so-called extrafloral nectaries to attract ants which in turn fend off herbivores. Scientists of the Max Planck Institute in Jena, Germany, have discovered that the production of extrafloral nectar is light dependent.

They have shown that the plants are able not only to distinguish between day and night, but also to adapt their nectar secretion to current light conditions by using a special photoreceptor, the phytochrome. Phytochrome probably influences the regulation of a special enzyme that binds the plant hormone jasmonic acid (JA) to the amino acid isoleucine (Ile). The emerging JA-Ile molecule affects the secretion of extrafloral nectar in such a way that the plant’s defense against herbivores is most effective whenever herbivory is most likely – or, more precisely, during the day. (PNAS Early Edition, DOI: 10.1073/pnas.1009007107)

Plants have to continuously defend themselves against herbivores to survive and reproduce. They do this directly by producing toxic substances, such as nicotine, or indirectly, by calling their enemies’ enemies for help. An example of an indirect defense is the release of volatile substances that attract predatory insects or parasitoids and guide them to their prey; for example, predatory wasps or bugs are led to a caterpillar that is feeding on a plant.

Another indirect defense is the secretion of extrafloral nectar from special leaf organs. In this way Lima beans attract ants that not only enjoy the sweet nectar but also defend the plant against herbivores. Scientists in the Department of Bioorganic Chemistry study this “sweet” defense mechanism. Radhika Venkatesan, a PhD student from India, completed a series of experiments on this topic and tested whether nectar secretion in Lima beans is light dependent. “After all, nectar consists mainly of sugars, and sugars are primary products in the process of photosynthesis – which depends on light,” notes the scientist. In the course of her studies, which were published in the Early Edition of the “Proceedings of the National Academy of Sciences USA” last week, she came across an old acquaintance in plant research – the so-called phytochrome. Plants contain phytochromes as photoreceptors in their leaves, which is the reason why phytochromes are sometimes called “the eye of the plant.”

“Not the light intensity, but light quality or composition plays a decisive role in regulating nectar production in Lima bean,” says Wilhelm Boland, director of the Max Planck Institute. As he explains, the phytochrome in the plant absorbs red light that enables the plant to distinguish the diurnal and seasonal variation of sunlight quality. Radhika Venkatesan’s experiments are the first to demonstrate that plants also use the phytochrome system to set up their lines of defense effectively and economically.

The hormone jasmonic acid is known as an important signal that plants produce after wounding by herbivores. It also plays a central role in regulating nectar secretion. The scientists have discovered that phytochrome-mediated light regulation has a significant impact on the signaling effect of jasmonic acid: Free jasmonic acid inhibits nectar secretion in the dark but stimulates its production in the light. Radhika Venkatesan found the key to this light-regulated behavior in a reaction that binds jasmonic acid to the amino acid isoleucine. The emerging conjugate JA-Ile is a signal molecule already known from other studies. For the first time, it has been identified as the actual elicitor of nectar secretion. Additional experiments have confirmed that nectar production doesn’t increase if binding of JA and isoleucine is prohibited by an inhibitor. If plants are wounded in the dark to stimulate JA production, JA-Ile is produced only in those leaves that were previously exposed to red light. [JWK, AO]

Original Publication:
Venkatesan Radhika, Christian Kost, Axel Mithöfer, Wilhelm Boland (2010). Regulation of extrafloral nectar secretion by jasmonates in lima bean is light dependent. Proceedings of the National Academy of Sciences USA, Early Edition, 20. September 2010, DOI: 10.1073/pnas.1009007107
Further Information:
Prof. Dr. Wilhelm Boland, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany. Tel.: +49 (0)3641- 57 1200; boland@ice.mpg.de
Picture Requests:
Angela Overmeyer, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Germany. Tel.: +49 (0)3641- 57 2110; overmeyer@ice.mpg.de

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de

Further reports about: DOI Ecology LIGHT Max Planck Institute amino acid floral nectar nectar toxic substance

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>