Scientists discover key mechanism with which plants cope with stress

Crops are facing a growing number of problems: too much water, too little sunlight, droughts, a changing atmosphere... In short, they are suffering from all kinds of stress. Climate change may make things worse by transforming certain regions into becoming high stress environments, whereas in others conditions will change in a more beneficial way, but requiring plants to adapt just as dramatically. In order to develop climate-resilient plants and to create robust energy crops, more insight is needed into how plants cope with stress.

Scientists from the Flanders Institute for Biotechnology (VIB), associated with the Katholieke Universiteit Leuven (K.U.Leuven, Belgium), have revealed a new mechanism demonstrating the intricate ways in which plants do just that. They found a crucial metabolic process which regulates the fine line between life and death. They publish their results in the advance online publication of Nature. The newly discovered control system has a remarkable way of orchestrating the activity of hundreds of genes, forcing plants into 'safety mode'; the consumption of energy is contained while the organism is stimulated to mobilize reserves. This may have a negative impact on growth, but it allows the plant to temporarily safeguard itself against pernicious stress conditions.

Photosynthetic plants are the principal solar energy converter sustaining life on Earth. But despite its fundamental importance, little is known about how plants sense and adapt to darkness in the daily light–dark cycle, or how they adapt to unpredictable environmental stresses that compromise photosynthesis and respiration and deplete energy supplies. With that most intricate of biochemical processes, called photosynthesis, plants catch sunlight and use it as an energy source to produce sugars from CO2 and water. In doing so, they are at the very basis of the food and energy chain of the planet. Without plants, life as we know it today would simply not be possible. So what if things go wrong when there is too little sunlight, for example? And what with other stressful conditions for plants, such as droughts or floods? Environmental changes can compromise the crucial engine of photosynthesis and exhaust energy supplies, simply leading to death.

Plants manage their own energy balance
Fortunately, plants have developed different mechanisms to detect and cope with these multiple forms of stress. Together with his American colleagues at Harvard Medical School (Boston, USA), VIB scientist Filip Rolland, associated with the Katholieke Universiteit Leuven, is uncovering a new system of detection and control.

It is driven by kinases 'KIN10' and 'KIN11'. These kinases, which are also found in human beings, react to energy shortages, when, for example, there is too little sunlight or too little sugar production. They control the activity of a broad network of genes, promoting the release of energy (catabolism) from alternative sources and blocking its assimilation (anabolism). In this way, the plant protects itself against stress conditions:
sustainability :: biomass :: bioenergy :: biofuels :: climate change :: stress :: plant biology :: metabolism :: energy :: photosynthesis ::

The key players: KIN10 & KIN11
The model organism for this study was Arabidopsis thaliana or thale cress. For decades, this small weed has been used as a model in molecular and genetic plant research. The scientists have tested numerous stress conditions that affect photosynthesis and energy production, such as darkness, herbicide treatment and flooding (lack of oxygen). By overexpressing the KIN10 gene, causing the plant to produce more of this protein, stress tolerance is increased and plants survive longer. By switching off these genes, their control function is eliminated.

With this research, the Flemish and American scientists have succeeded for the first time in attributing KIN10 and KIN11 a key role in the control of the plant energy budget and metabolism and thus the fragile balance between growth and survival; in short, the choice between life and death.

Interestingly the new insights gained by this study are not limited to the functioning of plants; they may also be important for human beings. KIN10 and KIN11, as 'fuel gauges' controlling the expression of a whole set of genes, are also found in mammals. The results with plants, therefore, may play a pioneering role in discovering new functions of these proteins in disorders such as diabetes, cancer, obesitas, and aging.

VIB, the Flanders Institute for Biotechnology, is a non-profit scientific research institute. Using advanced gene technology, VIB studies the functioning of the human body, plants and microorganisms.

Image: Arabidopsis thaliana, a model crop frequently used in plant biology research, with a growing part of its genome being sequenced and made available to the science community. Credit: The Scientist.

References:
Elena Baena-González, Filip Rolland, Johan M. Thevelein, & Jen Sheen, "A central integrator of transcription networks in plant stress and energy signalling", Nature advance online publication, doi:10.1038/nature06069; 1 August 2007

Eurekalert: Plants and stress -- key players on the thin line between life and death revealed - August 1, 2007.