Our primary research goal is to identify the key adaptive mechanisms that result in short- and long-term acquisition of abiotic stress tolerance. To address this, our research currently has two main themes: 1) how are environmental "signals" sensed and, in turn, converted into a genetic response, and 2) how is primary metabolism modulated in response to fluctuations in growth temperature. The outcomes from this research are being applied to developing new tools for increased stress tolerance in herbaceous crops and forest plantation species and to studies of how we can incorporate understanding of acclimation of primary metabolism into global circulation models.
One of the key questions on the international research agenda today is how various biotopes, natural and cultivated, will respond to the changes to the environment resulting from human activities. Plant carbon metabolism plays a crucial role in determining the functioning of terrestrial ecosystems, the concentration of CO2 in the atmosphere and the mean annual temperature of the earth's surface. Each year, photosynthetic carbon assimilation removes ca. 120 gigatonnes (Gt) of carbon from the atmosphere, with much of this carbon being used by heterotrophic organisms (i.e. animals, fungi, and bacteria).
In addition, plants return ca. 60 Gt carbon per year to the atmosphere via respiration when producing the energy and carbon intermediates necessary for biosynthesis and cellular maintenance.This is a very large flux compared with the ca. 8 Gt carbon per year released from the burning of fossil fuels. Thus, fundamental metabolic processes such as photosynthesis and respiration play a critical role in determining a wide range of ecological phenomena, from the productivity of individual plants, species fitness, particular environments, and the resulting species composition of particular biotopes. Understanding such processes, and how they respond to environmental perturbations, provides insight into the underlying mechanisms that will drive future phenotypic replacements in response to climate change. Growth temperature is one of the most important climate parameters that impacts on the global fluxes through these C-assimilatory and C-emission pathways. For example, as part of the thermal acclimation process (i.e. adjustment in the rate of metabolism to compensate for a change in growth temperature), cold-grown leaves exhibit higher transcript and activity levels of photosynthetic and sucrose synthesis enzymes, accompanied by increased capacity of mitochondrial electron transport than their warm-grown counterparts. As a result, sustained exposure to low growth temperatures typically results in an increase in the rate of assimilation and respiration at low temperatures. Given the predicted increase in the annual mean temperature of the Earth's surface, a major challenge for plant ecology and climate-vegetation modelling is identifying whether sustained changes in growth temperature will systematically alter the leaf-trait scaling relationships linking assimilation and respiration to leaf mass to area ratio and nitrogen concentrations. To answer this challenge, a far better understanding of the responses of organellar functions to fluctuations in environmental inputs (e.g. temperature, water and nutrients) is required. We have shown that incorporating acclimation into the predictive models results in significant regional effects on the prevalence of different functional groups in different biomes. For example, it alters the predictions of the abundance of needle trees in the boreal forest zone relative to broad-leafed trees. Such changes will have very significant consequences for major industries such as Sweden's forest industry and consequently for the national economy. Our future research will develop additional data sets to incorporate acclimation to temperature,variations in response to altered soil nutritional status, rainfall, etc. to improve the predictive capacity of climate models.
- Näsholm, T., Högberg, P., Franklin, O., Metcalfe, D., Keel, S.G., Campbell, C., Hurry, V., Linder, S., Högberg, M.N. (2013). Are ectomycorrhizal fungi alleviating or aggravating the N limitation to tree growth in boreal forests? New Phytologist. 198: 214-221.
- Ruelland, E., Vaultier, M.N., Zachowski, A., Hurry, V. (2009). Cold signalling and cold acclimation in plants. Advances in Botanical Research, 49: 36-149.
- Atkin OK, Atkinson LJ, Fisher RA, Campbell CD, Zaragoza-Castells J, Pitchford JW, Woodward FI, Hurry V (2008). Using temperature-dependent changes in leaf scaling relationships to quantitatively account for thermal acclimation of respiration in a coupled global climate-vegetation model. Global Change Biology, 14: 2709-2726.
- Högberg P, Högberg MN, Göttlicher SG, Betson NR, Keel SG, Metcalfe DB, Campbell C, Schindlbacher A, Hurry V, Lundmark T, Linder S, Näsholm T (2008). High temporal resolution tracing of photosynthate carbon from the tree canopy to forest soil micro- organisms. New Phytologist, 177: 220-228.
- Campbell C, Atkinson L, Zaragoza-Castells J, Lundmark M, Atkin O, Hurry V (2007). Acclimation of photosynthesis and respira- tion in response to changes in growth temperature is asynchronous across plant functional groups. New Phytologist, 176: 375–389