Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A place in the sun

07.04.2008
Those spindly plants that desperately try to reach for a break in the canopy formed by larger plants all suffer from the same affliction: Shade avoidance syndrome or SAS. Now, the molecular details of SAS have been brought to light by researchers at the Salk Institute for Biological Studies.

To step out of their neighbors’ shade, plants switch on a natural chemical factory for the synthesis of the plant growth hormone auxin that lets a plant grow and ultimately stretch toward the sun, the Salk researchers report in an article published in the April 4, 2008 issue of the journal Cell. Understanding this response at a molecular level will allow scientists to naturally manipulate this response to increase yield in crops ranging from rice to wheat.

“Plants compete with each other for light, and shade avoidance syndrome has a big ecological and economic impact, especially in the high density plantings typical of modern agriculture,” says Howard Hughes Medical Institute investigator Joanne Chory, Ph.D., a professor in the Plant Biology, who led the study. “Suppressing the shade avoidance reaction in crops may allow us to increase biomass and seed yield.”

Plants can sense and respond to the presence of other plants in their neighborhood by the relative increase in incoming far-red light resulting from absorption of red light by canopy leaves and reflection of far-red light from neighboring plants.

... more about:
»Arabidopsis »Auxin »Chory »Seed »Sun »Tryptophan »avoidance »enzyme »pathway

To secure their place in the sun, plants direct their growth resources toward stem elongation and away from bulking up harvestable portions such as leaves and seeds. “If all else fails, the plants put out what I like to call a premature ‘desperation flower’ to produce at least a couple of seeds that might find better growing conditions during the next season,” explains Chory.

In an earlier study, Chory had confirmed the existence of a separate molecular pathway that plants use to adjust their growth and flowering time to shade. But the molecular events linking the detection of changes in light quality to changes in growth patterns were still poorly understood.

To identify genes that are involved in the shade avoidance syndrome, first author Yi Tao, a postdoctoral researcher in Chory’s lab, searched a collection of mutated Arabidopsis thaliana seedlings for plants that no longer responded to crowded growth conditions. Like many commercially grown crops, Arabidopsis — the lab rat of plant biologists — doesn’t tolerate shade well.

She identified a handful of genes that play a role in the shade response, one of which encoded an enzyme similar to alliinase, the enzyme that produces the characteristic flavor of onion, garlic and other members of the Alliaceae plant family. To predict the function of the newly identified enzyme, Chory turned to her Salk colleague Howard Hughes Medical Institute investigator Joseph P. Noel, Ph.D, director of the Jack H. Skirball Center for Chemical Biology and Proteomics.

Although Arabidopsis lacks garlic’s pungency, Noel could model the newly discovered enzyme’s structure based on the already-known, three-dimensional structure of alliinase. “The active site chemically resembled a nook and cranny likely to bind the amino acid tryptophan,” says Noel. “That’s when it became really exciting since we knew that plants can use tryptophan to synthesize auxin.”

After virtual biochemistry led the way, real-life biochemistry confirmed that the enzyme indeed uses tryptophan to catalyze the first reaction in a three-step auxin-synthesis pathway and the new enzyme became known as tryptophan aminotransferase of Arabidopsis, or TAA1 for short.

Despite the importance of auxin for plant growth and development, the details of how auxin is synthesized continue to puzzle plant biologists. Multiple biochemical pathways for the production of auxin have been identified or proposed but the specific function of each pathway and how they intersect is not known. Now, the role of at least one pathway has become clearer.

“When the major photoreceptor for shade avoidance detects neighbors, it triggers the TAA1 pathway resulting in a rapid increase in free auxin, which is transported to sites in the stem where it can participate in the growth response,” explains Chory. “Although we showed earlier that at least two additional biosynthetic routes to auxin exist in Arabidopsis, these other pathways are unable to compensate for the loss of the TAA1-dependent pathway.”

Gina Kirchweger | EurekAlert!
Further information:
http://www.salk.edu

Further reports about: Arabidopsis Auxin Chory Seed Sun Tryptophan avoidance enzyme pathway

More articles from Life Sciences:

nachricht Turning carbon dioxide into liquid fuel
06.08.2020 | DOE/Argonne National Laboratory

nachricht Tellurium makes the difference
06.08.2020 | Friedrich-Schiller-Universität Jena

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: ScanCut project completed: laser cutting enables more intricate plug connector designs

Scientists at the Fraunhofer Institute for Laser Technology ILT have come up with a striking new addition to contact stamping technologies in the ERDF research project ScanCut. In collaboration with industry partners from North Rhine-Westphalia, the Aachen-based team of researchers developed a hybrid manufacturing process for the laser cutting of thin-walled metal strips. This new process makes it possible to fabricate even the tiniest details of contact parts in an eco-friendly, high-precision and efficient manner.

Plug connectors are tiny and, at first glance, unremarkable – yet modern vehicles would be unable to function without them. Several thousand plug connectors...

Im Focus: New Strategy Against Osteoporosis

An international research team has found a new approach that may be able to reduce bone loss in osteoporosis and maintain bone health.

Osteoporosis is the most common age-related bone disease which affects hundreds of millions of individuals worldwide. It is estimated that one in three women...

Im Focus: AI & single-cell genomics

New software predicts cell fate

Traditional single-cell sequencing methods help to reveal insights about cellular differences and functions - but they do this with static snapshots only...

Im Focus: TU Graz Researchers synthesize nanoparticles tailored for special applications

“Core-shell” clusters pave the way for new efficient nanomaterials that make catalysts, magnetic and laser sensors or measuring devices for detecting electromagnetic radiation more efficient.

Whether in innovative high-tech materials, more powerful computer chips, pharmaceuticals or in the field of renewable energies, nanoparticles – smallest...

Im Focus: Tailored light inspired by nature

An international research team with Prof. Cornelia Denz from the Institute of Applied Physics at the University of Münster develop for the first time light fields using caustics that do not change during propagation. With the new method, the physicists cleverly exploit light structures that can be seen in rainbows or when light is transmitted through drinking glasses.

Modern applications as high resolution microsopy or micro- or nanoscale material processing require customized laser beams that do not change during...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“Conference on Laser Polishing – LaP 2020”: The final touches for surfaces

23.07.2020 | Event News

Conference radar for cybersecurity

21.07.2020 | Event News

Contact Tracing Apps against COVID-19: German National Academy Leopoldina hosts international virtual panel discussion

07.07.2020 | Event News

 
Latest News

Rare Earth Elements in Norwegian Fjords?

06.08.2020 | Earth Sciences

Anode material for safe batteries with a long cycle life

06.08.2020 | Power and Electrical Engineering

Turning carbon dioxide into liquid fuel

06.08.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>