Featured Research

from universities, journals, and other organizations

Biologists Solve Plant Growth Hormone Enigma

Date:
July 3, 2006
Source:
University Of California, San Diego
Summary:
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.

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

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.

“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.
Click image for high-resolution version.

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.


Story Source:

The above story is based on materials provided by University Of California, San Diego. Note: Materials may be edited for content and length.


Cite This Page:

University Of California, San Diego. "Biologists Solve Plant Growth Hormone Enigma." ScienceDaily. ScienceDaily, 3 July 2006. <www.sciencedaily.com/releases/2006/07/060703091604.htm>.
University Of California, San Diego. (2006, July 3). Biologists Solve Plant Growth Hormone Enigma. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2006/07/060703091604.htm
University Of California, San Diego. "Biologists Solve Plant Growth Hormone Enigma." ScienceDaily. www.sciencedaily.com/releases/2006/07/060703091604.htm (accessed April 21, 2014).

Share This



More Plants & Animals News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mich. Boy Unearths 10,000-Year-Old Mastodon Tooth

Mich. Boy Unearths 10,000-Year-Old Mastodon Tooth

Newsy (Apr. 20, 2014) A 9-year-old Michigan boy was exploring a creek when he came across a 10,000-year-old tooth from a prehistoric mastodon. Video provided by Newsy
Powered by NewsLook.com
Vermont Goat Meat Gives Refugees Taste of Home

Vermont Goat Meat Gives Refugees Taste of Home

AP (Apr. 18, 2014) Dairy farmers and ethnic groups in Vermont are both benefiting from a unique collaborative effort that's feeding a growing need for fresh and affordable goat meat. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins