Drought resistance explained

November 09, 2009

Grenoble, 8 November 2009 - Much as adrenaline coursing through our veins drives our body's reactions to stress, the plant hormone abscisic acid (ABA) is behind plants' responses to stressful situations such as drought, but how it does so has been a mystery for years. Scientists at the European Molecular Biology Laboratory (EMBL) in Grenoble, France, and the Consejo Superior de Investigaciones Cientificas (CSIC) in Valencia, Spain discovered that the key lies in the structure of a protein called PYR1 and how it interacts with the hormone. Their study, published online today in Nature, could open up new approaches to increasing crops' resistance to water shortage.

Under normal conditions, proteins called PP2Cs inhibit the ABA pathway, but when a plant is subjected to drought, the concentration of ABA in its cells increases. This removes the brake from the pathway, allowing the signal for drought response to be carried through the plant's cells. This turns specific genes on or off, triggering mechanisms for increasing water uptake and storage, and decreasing water loss. But ABA does not interact directly with PP2Cs, so how does it cause them to be inhibited? Recent studies had indicated that the members of a family of 14 proteins might each act as middle-men, but how those proteins detected ABA and inhibited PP2Cs remained a mystery - until now.

A group of scientists headed by José Antonio Márquez from EMBL Grenoble and Pedro Luis Rodriguez from CSIC looked at one member of this family, a protein called PYR1. When they used X-ray crystallography to determine its 3-dimensional structure, the scientists found that the protein looks like a hand. In the absence of ABA, the hand remains open, but when ABA is present it nestles in the palm of the PYR1 hand, which closes over the hormone as if holding a ball, thereby enabling a PP2C molecule to sit on top of the folded fingers. As these features seem to be conserved across most members of this protein family, these findings confirm the family as the main ABA receptors. Moreover, they elucidate how the whole process of stress response starts: by binding to PYR1, ABA causes it to hijack PP2C molecules, which are therefore not available to block the stress response.

"If you treat plants with ABA before a drought occurs, they take all their water-saving measures before the drought actually hits, so they are more prepared, and more likely to survive that water shortage - they become more tolerant to drought", Rodriguez explains. "The problem so far", Márquez adds, "has been that ABA is very difficult - and expensive - to produce. But thanks to this structural biology approach, we now know what ABA interacts with and how, and this can help to find other molecules with the same effect but which can be feasibly produced and applied."

To determine the structure of PYR1, the scientists made use of the infrastructure of the Partnership for Structural Biology, including EMBL Grenoble's high-throughput crystallisation facilities and the beamlines at the European Synchrotron Radiation Facility, located in the same campus as EMBL Grenoble.
-end-


European Molecular Biology Laboratory

Related Stress Articles from Brightsurf:

Stress-free gel
Researchers at The University of Tokyo studied a new mechanism of gelation using colloidal particles.

Early life stress is associated with youth-onset depression for some types of stress but not others
Examining the association between eight different types of early life stress (ELS) and youth-onset depression, a study in JAACAP, published by Elsevier, reports that individuals exposed to ELS were more likely to develop a major depressive disorder (MDD) in childhood or adolescence than individuals who had not been exposed to ELS.

Red light for stress
Researchers from the Institute of Industrial Science at The University of Tokyo have created a biphasic luminescent material that changes color when exposed to mechanical stress.

How do our cells respond to stress?
Molecular biologists reverse-engineer a complex cellular structure that is associated with neurodegenerative diseases such as ALS

How stress remodels the brain
Stress restructures the brain by halting the production of crucial ion channel proteins, according to research in mice recently published in JNeurosci.

Why stress doesn't always cause depression
Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.

How plants handle stress
Plants get stressed too. Drought or too much salt disrupt their physiology.

Stress in the powerhouse of the cell
University of Freiburg researchers discover a new principle -- how cells protect themselves from mitochondrial defects.

Measuring stress around cells
Tissues and organs in the human body are shaped through forces generated by cells, that push and pull, to ''sculpt'' biological structures.

Cellular stress at the movies
For the first time, biological imaging experts have used a custom fluorescence microscope and a novel antibody tagging tool to watch living cells undergoing stress.

Read More: Stress News and Stress Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.