On guard against drought

Oct 28, 2011
Figure 1: Thermal images of control plants (left) with normal leaf temperature, and atabcg22 mutant plants (right), with lower leaf temperature and greater water loss, captured by an infrared thermography device. Credit: Ref. 1 © 2011 Blackwell Publishing Ltd

Identification of a gene that helps plants to conserve water under drought conditions will bring biologists closer to understanding how plants tolerate drought. Researchers, led by Takashi Kuromori at Japan's RIKEN Plant Science Center, Yokohama, report this discovery in The Plant Journal.

In order to grow, must take up carbon dioxide via gas exchange from the atmosphere for photosynthesis, which occurs through tiny pores called stomata on the surface of leaves and other aerial organs. However, plants also lose water during this opening through a separate process called transpiration.

During drought, plants protect themselves from excessive by closely regulating stomatal opening and closing. Each stomatal pore is flanked by a pair of kidney-shaped . When the plant becomes desiccated, the plant (ABA) mediates the by facilitating stomatal closure through its action on the specialized guard cells. Only when sufficient water is available do the guard cells change back to their original shape, opening the pore and allowing transpiration to resume.

“We wish to understand the molecular mechanisms that trigger guard cell responses to environmental and hormonal stimuli,” explains Kuromori.

Working with the plant Arabidopsis thaliana, Kuromori and colleagues previously identified a gene called AtABCG25, which is expressed in vascular tissues and is involved in ABA transport and responses*. In their latest work, they identified a related gene called AtABCG22, which is expressed predominantly in guard cells and regulates stomata in Arabidopsis. Both genes encode ‘ATP-binding cassette’ (ABC) transporter proteins, which use chemical energy stored in the biological molecule ATP to ferry other molecules across cell membranes. 

Evaporative cooling during transpiration reduces leaf temperature. Thermal imaging methods can therefore be used to monitor transpirational water loss (Fig. 1). Using such methods, the researchers showed that mutant plants lacking functional AtABCG22 protein had lower leaf temperature and increased water loss compared to normal, wild-type plants. They also found that the mutant plants were more susceptible to drought stress than were wild-type plants. “These findings imply that AtABCG22 plays a role in stomatal regulation and in protecting plants against drought stress,” says Kuromori.

Further experiments, in which the researchers crossed various mutant plants, revealed that AtABCG22 interacts genetically with other genes already known to be involved in ABA biosynthesis, transport or signaling.

“Our next task will be to identify the exact target molecule, or molecules of AtABCG22,” says Kuromori. “We hope that our work will eventually lead to the breeding of drought-tolerant crop varieties.”

Explore further: Free the seed: OSSI nurtures growing plants without patent barriers

More information: Kuromori, T., et al. Arabidopsis mutants of AtABCG22, an ABC transporter gene, increase water transpiration and drought susceptibility. The Plant Journal 67, 885–894 (2011). 

*Kuromori, T., et al. ABC transporter AtABCG25 is involved in abscisic acid transport and responses. Proceedings of the National Academy of Sciences USA 107, 2361–2366 (2010).

add to favorites email to friend print save as pdf

Related Stories

A new transporter gene that regulates plant transpiration

Sep 09, 2011

When plants feel stress from a lack of water, they close their epidermal pores, or stomata, to prevent water loss via transpiration. Each stoma is flanked by a pair of guard cells, which change shape to close or open stomata ...

Gene helps plants use less water without biomass loss

Jan 11, 2011

(PhysOrg.com) -- Purdue University researchers have found a genetic mutation that allows a plant to better endure drought without losing biomass, a discovery that could reduce the amount of water required for growing plants ...

Plant gene for water efficiency found

Jul 11, 2005

ANU researchers have identified a gene that regulates the water efficiency of plants, the first to be discovered that mediates the process critical to plant survival, crop yield and vegetation dynamics. Dr Josette Masle, fro ...

Adjustable valves gave ancient plants the edge

Jun 09, 2011

Controlling water loss is an important ability for modern land plants as it helps them thrive in changing environments. New research from the University of Bristol, published today in the journal Current Biology, shows ...

A doorman in plant cells

Jun 20, 2008

Scientists at the University of Tübingen, Germany identified important signalling-protein for the stress-response of plant cells. The research group of Klaus Harter at the Centre for Plant Molecular Biology (ZMBP), University ...

Recommended for you

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.