Navigation Links
Plant biology discovery furthers scientists' understanding of plant growth and development

RIVERSIDE, Calif. Auxin, a small molecule, is a plant hormone discovered by Charles Darwin about 100 years ago. Over the years that followed it became understood to be the most important and versatile plant hormone controlling nearly all aspects of plant growth and development, such as bending of shoots toward the source of light (as discovered by Darwin), formation of new leaves, flowers, and roots, growth of roots, and gravity-oriented growth. Just how a small molecule like auxin could play such a pivotal role in plants baffled plant biologists for decades.

Then, about ten years ago, an auxin sensing and signaling system was discovered in the cell's nucleus, but it could not explain all the diverse roles of auxin.

Now, plant cell biologists at the University of California, Riverside have discovered a new auxin sensing and signaling complex, one that is localized on the cell surface rather than in the cell's nucleus. The discovery provides new insights into the mode of auxin action, the researchers say.

"This is a new milestone in auxin biology and will ignite interest in the field," said Zhenbiao Yang, a professor of cell biology in the Department of Botany and Plant Sciences, and the leader of the research project. "Our findings conclusively demonstrate the existence of an extracellular auxin sensing system in plants, which had long been proposed but remained elusive. Further, we have uncovered the decades-long mystery of how ABP1, an auxin-binding protein, works to control plant developmental processes."

ABP1 was identified more than 40 years ago, but its role was hotly debated among plant biologists because its mode of action remained unclear until the recent discovery by Yang's team.

The team also showed that the cell surface auxin sensing system involves "transmembrane receptor kinases" (TMKs) enzymes widespread throughout eukaryotes that typically act as cell surface sensors for extracellular stimuli and translate them into intracellular responses.

"This breakthrough discovery of the cell surface ABP1/TMK auxin sensing system dramatically elevates the level of our understanding of how auxin plays diverse roles," said Natasha Raikhel, a distinguished professor of plant cell biology at UC Riverside, who was not involved in the research. "This signaling mechanism now serves as a paradigm for elucidating the molecular mechanisms underlying various auxin-modulated developmental processes and patterns. In addition to their major impact on the field of plant development and morphogenesis and plant signal transduction, Yang's discoveries also provide novel means of engineering plants with desired morphological traits and growth patterns."

Study results appear in the Feb. 28 issue of Science.

Yang's lab has been studying molecular mechanisms for the formation of the jigsaw puzzle-piece shape of pavement cells in leaf epidermis of the Arabidopsis plant, a small flowering plant widely used in plant biology laboratories as a model organism. It is the interlocking feature of these cells that provides the required physical strength and integrity for flat, thin leaves.

In previous work, the lab found that auxin activated the formation of the puzzle piece shape through ABP1 and ABP1-dependent activation of "ROP GTPases," which are pivotal regulatory proteins that act as a molecular switch in gating incoming signals from the cell surface. It was unclear, however, whether ABP1 was a cell surface auxin receptor. Also, just how it led to the activation of ROP GTPases remained unknown.

"But now we have identified a family of TMKs that physically and functionally interact with ABP1 to perceive and transduce auxin signal at the cell surface," Yang said. "We show that ABP1 and TMKs form a new auxin sensing complex at the cell surface and that TMKs transmit extracellular auxin signals to ROP GTPases located just inside of the cell membrane. This novel auxin sensing and signaling system makes possible the formation of the jigsaw shape of leaf epidermal cells and many other auxin-mediated processes."

Next, Yang's team plans to investigate whether there are additional components in the cell surface auxin sensing complex, what specific pathways are regulated by the cell surface auxin sensor, and why plants need both the nuclear and extracellular auxin sensors.


Contact: Iqbal Pittalwala
University of California - Riverside

Related biology news :

1. Global survey of urban birds and plants find more diversity than expected
2. Exotic plant species alter ecosystem productivity
3. Excessive deer populations hurt native plant biodiversity
4. Small biomass power plants could help rural economies, stabilize national power grid, MU study finds
5. Serpentine ecosystems shed light on the nature of plant adaptation and speciation
6. Europe must improve its response to the threat of plant pests and diseases
7. U of M-led study finds herbivores can offset loss of plant biodiversity in grassland
8. Transplanted human umbilical cord blood cells improved heart function in rat model of MI
9. Silk-based surgical implants could offer a better way to repair broken bones
10. Plant extract offers hope for infant motor neuron therapy
11. Are plants more intelligent than we assumed?
Post Your Comments:
Related Image:
Plant biology discovery furthers scientists' understanding of plant growth and development
(Date:6/22/2016)... 2016   Acuant , the leading ... has partnered with RightCrowd ® to ... Management, Self-Service Kiosks and Continuous Workforce Assurance. ... functional enhancements to existing physical access control ... with an automated ID verification and authentication ...
(Date:6/21/2016)... British Columbia , June 21, 2016 /PRNewswire/ ... appointed to the new role of principal product ... been named the director of customer development. Both ... NuData,s chief technical officer. The moves reflect NuData,s ... teams in response to high customer demand and ...
(Date:6/16/2016)... 2016 The global ... reach USD 1.83 billion by 2024, according to ... Technological proliferation and increasing demand in commercial buildings, ... drive the market growth.      (Logo: ... development of advanced multimodal techniques for biometric authentication ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... June 27, 2016  Alex,s Lemonade Stand Foundation (ALSF), ... it will open a state-of-the-art bioinformatics lab, using ,big ... This announcement comes as Liz Scott , co-executive ... Cancer Moonshot Summit in Washington, D.C. ... a participant and advocate of pediatric cancer research and ...
(Date:6/27/2016)... June 27, 2016  Global demand for enzymes ... through 2020 to $7.2 billion.  This market includes ... cleaning products, biofuel production, animal feed, and other ... and biocatalysts). Food and beverages will remain the ... increasing consumption of products containing enzymes in developing ...
(Date:6/27/2016)... ON , June 27, 2016 /PRNewswire/ - BIOREM Inc. ... has been advised by its major shareholders, Clean Technology ... United States based venture capital ... shares of Biorem (on a fully diluted, as converted ... the disposition of their entire equity holdings in Biorem ...
(Date:6/27/2016)... June 27, 2016  Sequenom, Inc. (NASDAQ: ... healthier lives through the development of innovative products and ... the United States denied its petition ... claims of Sequenom,s U.S. Patent No. 6,258,540 (",540 Patent") ... established by the Supreme Court,s Mayo Collaborative Services v. ...
Breaking Biology Technology: