Cross-talk between cold and light signalling pathways in Arabidopsis thaliana.

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When temperatures drop, we can put more clothes on, or turn the heating up. Plants can't. They can't move, so have to face the brunt of being cold. One of the major problems plants face is one they share with all other cellular life, namely that freezing of cells is very damaging. If that weren't bad enough, before temperatures even drop as low as freezing point, plants have another more specific problem. The definition of a plant is that it produces its own food, using light, via photosynthesis. The harnessing of such potent energy (sunlight), doesn't come without risks. The energy must be very efficiently coupled to producing sugar, or else the energy can cause damage to the plant cells (this is known as photooxidative stress). When temperatures drop, the efficient coupling of light energy becomes difficult, and the energy can produce highly reactive chemicals (reactive oxygen species, which act like bleach) that can damage and kill the plants. How do plants cope with these problems? Plants have a repertoire of different genes which they can switch on and off responsively to help them cope with changes in their environment. We know that when the temperature drops, a plant will switch on many genes whose purpose is to protect it from the consequences of frost damage. We have discovered a set of genes that are switched on by the plant in response to darkness but switched off during cold temperatures. Our research is aimed at discovering how the plant does this and what the benefit is of doing so. We will be looking for key patterns (sequences) in the DNA of these genes, which act as on/off switches when light levels or the temperature drop. By introducing artificial changes into these switching mechanisms and monitoring their effects, we will learn more about how the switches work. We can then examine the effect that switching the genes on and off has on the plant's ability to cope with life at low temperatures and in frost conditions.