Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCSD Biologists Solve Plant Growth Hormone Enigma

03.07.2006
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:
http://www.ucsd.edu

More articles from Life Sciences:

nachricht Climate Impact Research in Hannover: Small Plants against Large Waves
17.08.2018 | Leibniz Universität Hannover

nachricht First transcription atlas of all wheat genes expands prospects for research and cultivation
17.08.2018 | Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>