Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


UCSD Biologists Solve Plant Growth Hormone Enigma

Gardeners and farmers have used the plant hormone auxin for decades, but how plants produce and distribute auxin has been a long-standing mystery. Now researchers at the University of California, San Diego have found the solution, which has valuable applications in agriculture.

The study, published in the July 1 issue of the journal Genes and Development, describes the discovery of a whole family of auxin genes, and shows that each gene is switched on at a distinct location in the plant. Contrary to the current thinking in the field, the research shows that the patterns in which auxin is produced in the plant influence development, a finding that can be applied to improving crops.

Electron microscope image of the female portion of a normal (left) and auxin-deficient (right) flower. Credit: Yunde Zhao, UCSD

“The auxin field dates back to Charles Darwin, who first reported that plants produced a substance that made them bend toward light,” said Yunde Zhao, an assistant professor of biology at UCSD. “But until now, the auxin genes have been elusive. Our discovery of these genes and the locations where auxin is produced in the plant can be applied to agricultural problems, such as how to make seedless fruit or plants with stronger stems.”

Applying auxin to plants can have many different effects. For example, it can promote root development in cuttings, stimulate fruit development in the absence of fertilization or, in excess, kill weeds. However, this study is the first to show what happens in a plant when auxin production is turned off.

The researchers identified a family of 11 genes (YUCCA 1-11) that are involved in the synthesis of auxin. In Arabidopsis—a small plant favored by biologists because it is easy to manipulate genetically—Zhao’s team inactivated combinations of the YUCCA genes and studied the effects of the inactivations on plant growth and development.

“Plant biologists have wanted to do this experiment for a long time, but only recently have new genetic tools such as ‘reverse genetics’ and ‘activation tagging’ made it possible,” explained Youfa Cheng, a postdoctoral fellow working with Zhao. “Even with the advances in technology, it took about three years to produce plants lacking at least four of the 11 YUCCA genes.”

Disrupting one YUCCA gene did not have any obvious effects. Therefore, there is overlap in the functions of the genes in this family. However, when two or more YUCCA genes were inactivated, the plants had developmental defects. The defects, including flowers with missing or misshapen parts, or deformations in the tissues that transport water and nutrients throughout the plant, differed depending on which combinations of genes were deleted.

The researchers say that this finding was surprising because most people in the field thought that where auxin was made did not really matter. The widely held view was that auxin could just be transported wherever it was needed. Not so, because turning auxin off in specific tissues of the plant led to defects in those tissues, while the rest of the plant appeared normal.

“Knowing which auxin genes are activated when should make it possible to modify plant development,” said Zhao. “It wouldn’t require adding any new genes to the plant, just changing when the appropriate auxin genes were on or off could alter growth. For example, to make seedless tomatoes, one could activate auxin in the floral organs before fertilization has taken place.”

Applying auxin to the flowers by hand can also induce seedless tomatoes, or other seedless fruit, but this method is too tedious to be useful for commercial purposes. Seedless fruits would not just be novelty items. For example, Zhao points out that seeds significantly increase the effort and waste involved in producing tomato sauce.

“This study is a real tour de force,” commented Martin Yanofsky, a professor of biology at UCSD, who was not one of the authors of the study. “People have been trying to figure out auxin for decades. By carefully inactivating the genes for auxin synthesis one by one, the team was able to show how the localized production of auxin controls the architecture of a plant.”

Xinhua Dai, a research associate working with Zhao, also contributed to the study. This research was supported by the National Institutes of Health.

Media Contact: Sherry Seethaler, (858) 534-4656

Comment: Yunde Zhao, (858), 822-2670

Sherry Seethaler | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>