Featured Research

from universities, journals, and other organizations

Explaining How Ozone "Chokes Up" Plants

Date:
December 7, 1999
Source:
Penn State
Summary:
Penn State researchers have identified how ozone, a major smog constituent, affects the microscopic breathing pores on plants' leaves, a process that may figure in the estimated $3 billion in agricultural losses caused by ozone air pollution in the U.S. each year.

University Park, Pa. --- Penn State researchers have identified how ozone, a major smog constituent, affects the microscopic breathing pores on plants' leaves, a process that may figure in the estimated $3 billion in agricultural losses caused by ozone air pollution in the U.S. each year.

Related Articles


Dr. Gro Torsethaugen, a postdoctoral researcher in Penn State's Environmental Resources Research Institute, says, "Although elevated ground levels of ozone resulting from traffic and other fossil fuel burning have long been associated with losses in agricultural yield, the precise cellular targets of ozone's action were essentially unknown. Our work has shown, for the first time, that, rather than causing the pores or stomates on a plant's leaves to close, as was generally assumed, ozone actually inhibits stomatal opening by directly affecting the 'guard cells' that control the opening."

Torsethaugen adds that knowing ozone's specific cellular targets may make it possible in the future to breed or to genetically engineer new plant varieties to improve productivity in geographic regions, such as California, with significant ozone exposure.

Torsethaugen and her co-authors Dr. Eva J. Pell, the Steimer professor of agricultural sciences, and Dr. Sarah M. Assmann, professor of biology, published their findings in a recent issue of the Proceedings of the National Academy of Sciences (PNAS).

Plants take in the carbon dioxide they need for photosynthesis through their stomates, Torsethaugen explains. They also release oxygen made in photosynthesis through the same pores. Ozone can also enter the plant through the stomates and can affect photosynthesis via that route. The Penn State experiments point to direct action on the guard cells as an additional path that ozone takes to decrease carbon dioxide assimilation and reduce plant productivity.

Torsethaugen conducted the experiments with fava bean plants, an important world food source and a species scientists favor for guard cell studies. Using various techniques, she examined the pores on the leaves of whole plants and portions of leaf surfaces and then studied the isolated guard cells.

In whole plants and the leaf surfaces, she found that ozone directly affects the stomatal opening.

Using isolated guard cells, she monitored the flow of potassium, in a positively charged or ion form, into and out of the cells.

"We monitored potassium because it is a major component in the osmotic process," she says. "If the potassium ion concentration is increased, water comes into the cell by osmosis and the guard cells surrounding the stomate swell. This swelling causes the pore to open."

Ozone exposure reduced the flow of potassium ions into the guard cells but did not affect the outward flow, indicating that ozone inhibits the opening of the pores.

In their PNAS paper, the authors note that their findings may have particular relevance during drought. They write, "Stomatal closure during a period of drought may be less readily reversed in ozone-exposed plants. This may be particularly relevant because the highest ozone concentrations are sometimes associated with times of drought."

In addition, they write "In major agricultural regions with high light environments and significant ozone exposure - e.g. the "South Coast Air Basin of California, which has the most extreme ozone levels in the U.S. - midday stomatal closure often occurs because of the low ambient humidity that results from the high light, high temperature conditions of midday. Because the generation of ozone in photochemical smog depends on high solar irradiation, ozone inhibition of stomatal opening could significantly retard stomatal reopening in the afternoon after this mid-day depression and consequently reduce crop yield."

Identification of the potassium ion channel as a target for ozone action opens the door to selectively breeding or genetically engineering less ozone sensitive plants to improve plant productivity in geographic regions with significant ozone expose.

However, the Penn State researchers also note that "Our identification of a specific ion channel as a target for ozone action may prompt comparable studies in mammalian system, leading to improved understanding of and treatment for the disease etiologies exacerbated by ozone. "

The research was supported in part by a grant from the Binational Agricultural Research and Development/U.S. Department of Agriculture. The Department of Biology, University of Oslo, Norway, where Torsethaugen earned her doctorate, provided additional support.


Story Source:

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


Cite This Page:

Penn State. "Explaining How Ozone "Chokes Up" Plants." ScienceDaily. ScienceDaily, 7 December 1999. <www.sciencedaily.com/releases/1999/12/991207072741.htm>.
Penn State. (1999, December 7). Explaining How Ozone "Chokes Up" Plants. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/1999/12/991207072741.htm
Penn State. "Explaining How Ozone "Chokes Up" Plants." ScienceDaily. www.sciencedaily.com/releases/1999/12/991207072741.htm (accessed October 25, 2014).

Share This



More Earth & Climate News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. 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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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