Featured Research

from universities, journals, and other organizations

How A Plant Know To Send Roots Down And Shoots Up: EAR Calls The Shots

Date:
February 13, 2008
Source:
Salk Institute
Summary:
Controlled by a tightly regulated choreography that determines what should go up and what should go down, plants develop along a polar axis with a root on one end and a shoot on the other. Turns out the question, "Root or shoot?" literally hinges on the EAR domain, a short protein sequence only six amino acids long.

The lens shaped cell (shown in green) at the base of the plant embryo (shown in red) will go on to form the center of the root meristem – the actively dividing cell tissue at the tips of roots. It fluoresces green in response to auxin, which governs root development (top left). Embryos with a mutation in the TOPLESS gene still respond normally to auxin (top right), while embryos without a functional version of BODENLOS cannot respond to auxin and as a result fail to develop roots (bottom left). Combining both mutations restores the auxin response as well as root development (bottom right).
Credit: Courtesy of Dr. Jeffrey Long, Salk Institute for Biological Studies

Controlled by a tightly regulated choreography that determines what should go up and what should go down, plants develop along a polar axis with a root on one end and a shoot on the other.

While studying why a defective TOPLESS gene causes plant embryos to develop into a seedling topped with a second root instead of a stem with leaves, researchers at the Salk Institute for Biological Studies hit upon the linchpin that ensures that plants are neither all root nor all shoot.

Turns out the question, "Root or shoot?" literally hinges on the EAR domain, a short protein sequence only six amino acids long.

The Salk researchers' findings, published in the February 7 issue of Science Express, explain how mutations in TOPLESS can switch a plant cell's fate from shoot to root and in the process clarify the purpose of the so-called EAR motif, a protein domain whose function has puzzled plant scientists for several years.

"We've known for a while that the EAR domain can turn off transcription, but how it did this was an open question," says the study's lead author, Jeffrey A. Long, Ph.D., an assistant professor in the Plant Molecular and Cellular Biology Laboratory. "We didn't set out to fish for molecules that bind to the EAR domain, but when we used TOPLESS as a bait, that's what we found."

Scientists and home gardeners alike have been messing with plants' basic architecture for years: Permanently switch on a gene called BODENLOS (or bottomless) and plants forgo root development altogether. Dip plant cuttings into hormone rooting powder and roots start to sprout where none have been. The active ingredient, a synthetic version of the plant hormone auxin that regulates root growth in plants, overrides the molecular switch that keeps auxin-responsive genes turned off in parts of the plant that are above ground.

In an earlier study, Long and his team had discovered that the switch is none other than TOPLESS, the protein encoded by the TOPLESS gene. It had become clear that TOPLESS functions as a so-called co-repressor, which regulate gene expression by inhibiting the activity of transcription factors. Transcription factors control gene activity by binding to DNA sequences adjacent to a gene. But exactly how TOPLESS silences genes necessary for root development has remained unclear.

Hoping to gain insight into how TOPLESS functions by looking at the company it keeps, lead author Heidi Szemenyei, a former graduate student in Long's lab and now a postdoctoral researcher at UC Berkeley, searched for interacting partners in the plant Arabidopsis thaliana. This wee weed was the first flowering plant to have its genome unlocked and is loved by plant biologists for its short generation time.

She discovered that BODENLOS, a transcriptional repressor that silences auxin-responsive genes, relies on its EAR domain to recruit the co-repressor TOPLESS to help with the job. While auxins are found throughout the whole plant, BODENLOS is only active in the shoot, ensuring that no accidental roots sprout above ground.

"The coupling of TOPLESS to BODENLOS provides an elegant mechanism for the plant to control the activity of auxin-responsive genes," says Long.

Mike Hannon, a graduate student in Long's lab also contributed to the study.


Story Source:

The above story is based on materials provided by Salk Institute. Note: Materials may be edited for content and length.


Cite This Page:

Salk Institute. "How A Plant Know To Send Roots Down And Shoots Up: EAR Calls The Shots." ScienceDaily. ScienceDaily, 13 February 2008. <www.sciencedaily.com/releases/2008/02/080207140806.htm>.
Salk Institute. (2008, February 13). How A Plant Know To Send Roots Down And Shoots Up: EAR Calls The Shots. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2008/02/080207140806.htm
Salk Institute. "How A Plant Know To Send Roots Down And Shoots Up: EAR Calls The Shots." ScienceDaily. www.sciencedaily.com/releases/2008/02/080207140806.htm (accessed July 24, 2014).

Share This




More Plants & Animals News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. Video provided by Newsy
Powered by NewsLook.com
Stone Fruit Listeria Scare Causes Sweeping Recall

Stone Fruit Listeria Scare Causes Sweeping Recall

Newsy (July 22, 2014) The Wawona Packing Company has issued a voluntary recall on the stone fruit it distributes due to a possible Listeria outbreak. Video provided by Newsy
Powered by NewsLook.com
Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
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