Drought alarm found in plants

ARC CENTRE OF EXCELLENCE IN PLANT ENERGY BIOLOGY

Scientists have found a signal in plants which may act as a drought alarm, allowing them to adapt to drought conditions. Image: amphotora/iStockphoto Scientists have found a signal in plants which may act as a drought alarm, allowing them to adapt to drought conditions. The signal was discovered while trying to understand how different parts of the cell "talk" to each other under drought conditions in the model plant Arabidopsis thaliana, a relative of canola. Inside every animal and plant cell there are a series of connected pathways, like the production lines of a factory. For it to work efficiently, each department must be able to communicate product shortages, adverse conditions or breakdowns. In cells, the production lines, or pathways, are regulated by chemical signals and inputs, which can come from many sources. Scientists have proposed for a while that chemical signals must be sent by a particular "plant department", or organelle, to the nucleus - the cell's control centre - for plants to become aware of and adapt to harsh conditions. "The chloroplast is the plant organelle that converts light into food. The nucleus directs assembly and function of the chloroplast and this requires cross-talk between the two", Dr Estavillo said. Despite these signals being proposed, they have been greatly debated and the signalling mechanisms for "talk" remain unclear. But now, research on a mutant variety of Arabidopsis has lead to the discovery of a signal to the nucleus which is important in the plant response to drought. This research was lead by Dr Gonzalo Estavillo and Prof. Barry Pogson at the Australian National University node of the ARC Centre for Excellence in Plant Energy Biology (Estavillo et al. (2011) The Plant Cell). The Arabidopsis mutant plant lacked a protein called SAL1, which breaks down a small molecule further down the production line called "PAP". As the protein was absent, the production line was broken, so "PAP", which is usually found in the chloroplast, ended up building up in the nucleus. Surprisingly, this became a kind of drought alarm, telling the plant to save water. Consequently these mutant plants survived 50% longer in drought conditions. More importantly, the researchers found that normal plants also accumulated PAP during drought conditions and that the PAP molecule was able to move between the chloroplast and the nucleus. "We intend to fully investigate the potential of this remarkable PAP signal", says Dr Estavillo. "It's a great time to be a plant scientist. We have the technology to decipher tiny and crucial molecular pathways in cells and use this knowledge to improve plant breeding and genetics. After all, plants are our food and fuel future." Editor's Note: Original news release can be found here.