Featured Research

from universities, journals, and other organizations

Unlocking the secrets of a plant’s light sensitivity

Date:
December 27, 2010
Source:
Carnegie Institution
Summary:
Plants are very sensitive to light conditions, in part due to a signal that activates special photoreceptors that regulate growth, metabolism, and physiological development. Scientists believe that these light signals control plant growth and development by activating or inhibiting plant hormones. New research has altered the prevailing theory on how light signals and hormones interact. The findings could have implications for food crop production.

Plants are very sensitive to light conditions because light is their source of energy and also a signal that activates the special photoreceptors that regulate growth, metabolism, and physiological development. Scientists believe that these light signals control plant growth and development by activating or inhibiting plant hormones. New research from Carnegie plant biologists has altered the prevailing theory on how light signals and hormones interact. Their findings could have implications for food crop production.

It was previously known that a plant hormone called brassinosteroid is essential for plant's responses to light signals. This crucial steroid-type hormone is found throughout the plant kingdom and regulates many aspects of growth and development. Surprising new research from a team led by Carnegie plant biologist Zhi-Yong Wang shows that light does not control the level of brassinosteroid found in plants as was expected. Instead brassinosteroid dictates the light-sensitivity of the plant. It does this by controlling the production of a key light-responsive protein.

The team's findings on interactions between brassinosteroid and light in sprouting seedlings have changed the prevailing model for understanding the relationship between light conditions and hormone signals in regulating photosynthesis and growth. Their results are published in Developmental Cell on December 14.

While under the soil's surface, in the dark, plant seedlings grow in a special way that speeds the process of pushing the budding stem out into the air, while simultaneously protecting it from damage. This type of growth is called skotomorphogenesis. Once exposed to light, seedlings switch to a different, more regular, type of growth, called photomorphogenesis, during which the lengthening of the stem is inhibited and the leaves expand and turn green.

Many components are involved in this developmental switch, including brassinosteroid. Previous studies showed that mutant plants created to be deficient in brassinosteroid grew as if they were in the light, even when in the dark. Research also showed that many genes responded to stimulation from light and brassinosteroid in opposite ways. But scientists were unsure how this antagonistic process worked, especially after they found the levels of brassinosteroid in plant cells were not significantly different between plants grown in the dark or in the light.

The Carnegie team's new research identifies a protein called GATA2 as a missing link in this communications system. This protein tells developing seedlings which type of growth to pursue.

GATA2 is part of the GATA factor class of proteins, which are found in plants, fungi and many animals. GATA factors promote the construction of a variety of new proteins, the recipes for which are encoded in DNA. It does this by switching on and off different genes. In Arabidopsis, the experimental mustard plant used in this study, there are 29 genes for different members of the GATA factor family. Some of these have been demonstrated to play a role in flower development, the metabolism of carbon and nitrogen, and the production of the green pigment chlorophyll.

Wang's team found that GATA2 switches on many genes that are turned on by light but turned off by brassinosteroid. It then showed that brassinosteroid inhibits the production of GATA2 and light stabilizes the presence of GATA2 protein in plant cells.

First, the team showed that GATA2 functions to turn on select plant growth genes in the presence of light. The scientists genetically manipulated Arabidopsis plants to cause the GATA2 protein to be overproduced. As a result, the plants started to show patterns of growing in light, even when they were in the dark. This manipulation demonstrates that GATA2 is a major promoter of light-type growth.

What's more, this is the same reaction that was produced when plants were genetically manipulated to be brassinosteroid-deficient. This means that the over abundance of GATA2 had the same result as the scarcity of brassinosteroids. These results show that GATA2 proteins and brassinosteroid hormones have antagonistic effects on developing plants.

Next, the Carnegie team showed that brassinosteroid is actually involved in inhibiting the actions of GATA2. Brassinosteroids turn on a protein that prevents GATA2 from working when the seedling is in the dark. This inhibition of GATA2 is stopped by exposure to light. This likely happens due to the involvement of yet another protein -- one that is widely involved in light-signaling -- although further study is needed to be sure.

Together all these results show that GATA2 is an important factor in signaling light-type growth. It also serves as a communications junction between internal plant systems that are turned on by light and those that are turned on by brassinosteroids.

"Brassinosteroids and light antagonistically regulate the level of GATA2 activity, and thus the creation of proteins stimulated by GATA2," says Wang. "As a result, GATA2 represents a key junction of crosstalk between brassinosteroid and light signaling pathways."

The framework created by this research leaves plenty of avenues for further study of the various components of light signaling in plants. Some other members of the GATA class of proteins may be involved, as well as other light-responsive compounds.


Story Source:

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


Journal Reference:

  1. Xiao-Min Luo, Wen-Hui Lin, Shengwei Zhu, Jia-Ying Zhu, Yu Sun, Xi-Ying Fan, Menglin Cheng, Yaqi Hao, Eunkyoo Oh, Miaomiao Tian, Lijing Liu, Ming Zhang, Qi Xie, Kang Chong and Zhi-Yong Wang. Integration of Light- and Brassinosteroid-Signaling Pathways by a GATA Transcription Factor in Arabidopsis. Developmental Cell, Volume 19, Issue 6, 872-883, 14 December 2010 DOI: 10.1016/j.devcel.2010.10.023

Cite This Page:

Carnegie Institution. "Unlocking the secrets of a plant’s light sensitivity." ScienceDaily. ScienceDaily, 27 December 2010. <www.sciencedaily.com/releases/2010/12/101213163847.htm>.
Carnegie Institution. (2010, December 27). Unlocking the secrets of a plant’s light sensitivity. ScienceDaily. Retrieved August 2, 2014 from www.sciencedaily.com/releases/2010/12/101213163847.htm
Carnegie Institution. "Unlocking the secrets of a plant’s light sensitivity." ScienceDaily. www.sciencedaily.com/releases/2010/12/101213163847.htm (accessed August 2, 2014).

Share This




More Plants & Animals News

Saturday, August 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pyrenees Orphan Bear Cub Gets Brand New Home

Pyrenees Orphan Bear Cub Gets Brand New Home

AFP (Aug. 1, 2014) The discovery of a bear cub in the Pyrenees mountains made headlines in April 2014. Despire several attempts to find the animal's mother, the cub remained alone. Now, the Pyrenees Conservation Foundation has constructed an enclosure. Duration: 00:31 Video provided by AFP
Powered by NewsLook.com
Ebola Vaccine Might Be Coming, But Where's It Been?

Ebola Vaccine Might Be Coming, But Where's It Been?

Newsy (Aug. 1, 2014) Health officials are working to fast-track a vaccine — the West-African Ebola outbreak has killed more than 700. But why didn't we already have one? Video provided by Newsy
Powered by NewsLook.com
Study Links Certain Birth Control Pills To Breast Cancer

Study Links Certain Birth Control Pills To Breast Cancer

Newsy (Aug. 1, 2014) Previous studies have made the link between birth control and breast cancer, but the latest makes the link to high-estrogen oral contraceptives. Video provided by Newsy
Powered by NewsLook.com
Rare Whale Fossil Pulled from Calif. Backyard

Rare Whale Fossil Pulled from Calif. Backyard

AP (Aug. 1, 2014) A rare whale fossil has been pulled from a Southern California backyard. The 16- to 17-million-year-old baleen whale fossil is one of about 20 baleen whale fossils known to exist. (Aug. 1) 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