Low temperature acclimation in plants : alterations in photosynthetic carbon metabolism

Although low temperature plays an important role in determining agricultural yield, little is known about the effect on the underlying biochemical and physiological processes that influence plant growth. Photosynthesis and respiration are central to plant growth and both processes are heavily affected by temperature. However, many plants have the ability to cope with low temperature and resume growth by cold acclimating. We have shown that enhancement of carbon fixation, an increased flux of carbon into sucrose and the recovery of diurnal export is crucial for the recovery of functional carbon metabolism at low temperature in Arabidopsis thaliana. The recovery of efflux is governed by increased expression of sucrose transporters along with changes in vascularisation. We also demonstrate the importance of controlling the flux of metabolites between the chloroplast and the cytosol by regulating the expression of AtTPT. We further investigated the difference in response between leaves developed at low temperature but originating from warm grown Arabidopsis and leaves from plants grown from seed at low temperature. We were able to distinguish factors that respond specifically to low temperature from those that are connected to the actual stress. Substantial difference could be seen in the different metabolomes. One conclusion drawn is that the increase in sucrose reported at low temperature is an essential feature for life in the cold. In an extended study we were able to transfer some of the key factor of cold acclimation in Arabidopsis to other species. The study included forbs, grasses and evergreen trees/shrubs showed that there are striking similarities in the extent and biochemical changes that underpin acclimation among the different functional groups. Low temperature does not only influence growth of the leaves, perennial organs such as the corm of the ornamental plant Crocus vernus is also affected. However in these plants low temperature has a positive effect on the final size of the corm. We were able to show that this enhanced growth was an affect of increased cell size and thus increased sink capacity, which ultimately delays leaf senescenc