Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Many ways to grow

25.05.2009
Environmental conditions may determine which particular process plants will use to build an essential hormone

For the better part of a century, scientists have recognized indole-3-acetic acid (IAA), one of several hormones known as auxins, as one of the most important drivers of plant growth and development. However, it remains unclear exactly how IAA is synthesized. Previous research has identified at least four different enzymatic ‘assembly lines’ that may be involved in its production, and each of these pathways generates chemical compounds that are potential precursors to IAA, as well as a number of other biologically important molecules involved in protecting plants against predators and pathogens.

In the thale cress plant, Arabidopsis thaliana, indole-3-actaldoxime (IAOx) is thought to represent a likely intermediate compound in IAA production via two of these candidate pathways, CYP79B and YUC. In order to clarify which of these contribute primarily to production of IAOx and IAA, Hiroyuki Kasahara of the RIKEN Plant Science Center in Yokohama and colleagues generated several mutant Arabidopsis strains in which key enzymes in either pathway had been ablated.

From the data, the team consistently identified an exclusive role for the CYP79B pathway in IAOx production and—by extension—IAA synthesis, and demonstrated no effect on levels of either compound resulting from interference with YUC-associated enzymes1. They also identified two compounds, indole-3-acetamide and indole-3-acetonitrile, as likely intermediates in the conversion of IAOx to IAA. Many plant species, including tobacco and rice, lack the CYP79B pathway altogether and do not produce detectable IAOx. However, these plants do produce these other IAA intermediates, suggesting the existence of yet-unidentified, parallel biosynthetic pathways in these species.

These findings indicate the need for a considerable reorganization of existing models of plant hormone synthesis. “Before this research, three proposed pathways were thought to converge at IAOx or its metabolites,” says Kasahara. “We have clearly separated these pathways.” Interestingly, their data also revealed that even in Arabidopsis, CYP79B does not represent the primary pathway of IAA production; instead, it is simply one of several that appear to contribute under different, specific conditions—in this case, cultivation at higher than room temperature.

Other non-IAOx biosynthetic pathways appear to be common to most plant species and Kasahara and colleagues now hope to clarify their independent contributions to overall IAA production. “We do not know why plants have so many biosynthetic pathways for IAA,” he says. “Here we showed that the IAOx pathway contributes to IAA generation under high temperature conditions, and now we are studying the physiological roles of other IAA biosynthetic pathways.”

Reference

1. Sugawara, S., Hishiyama, S., Jikumaru, Y., Hanada, A., Nishimura, T., Koshiba, T., Zhao, Y., Kamiya, Y. & Kasahara, H. Biochemical analyses of indole-3-acetaldoxime-dependent auxin biosynthesis in Arabidopsis. Proceedings of the National Academy of Sciences USA 106, 5430–5435 (2009).

The corresponding author for this highlight is based at the RIKEN Growth Regulation Research Team

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/research/705/
http://www.researchsea.com

More articles from Life Sciences:

nachricht Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

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...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

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...

Im Focus: Breaking the bond: To take part or not?

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...

Im Focus: New 2D Spectroscopy Methods

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....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>