Atkinson, Lindsey J.Sherlock, David J.Atkin, Owen K.2015-09-152015-09-150140-7791http://hdl.handle.net/1885/15406To determine (1) whether acclimation of carbon metabolism to low temperatures results in recovery of the relative growth rate (RGR) of plants in the cold and (2) the source of N underpinning cold acclimation in Arabidopsis thaliana, we supplied plants with a nutrient solution labelled with (15) N and subjected them to a temperature shift (from 23 to 5 °C). Whole-plant RGR of cold-treated plants was initially less than 30% of that of warm-maintained control plants. After 14 d, new leaves with a cold-acclimated phenotype emerged, with the RGR of cold-treated plants increasing by 50%; there was an associated recovery of root RGR and doubling of the net assimilation rate (NAR). The development of new tissues in the cold was supported initially by re-allocation of internal sources of N. In the longer term, the majority (80%) of N in the new leaves was derived from the external solution. Hence, both the nutrient status of the plant and the current availability of N from external sources are important in determining recovery of growth at low temperature. Collectively, our results reveal that both increased N use efficiency and increases in nitrogen content per se play a role in the recovery of carbon metabolism in the cold.This work has been supported by an NERC-UK researchgrant to O.K.A (NER/B/S/2001/00875), funding to OKAfrom the ARC-Australia (CE140100008) and by a DaphneJackson Fellowship to L.J.A. funded by the NERC-UK.© 2014 John Wiley & Sons Ltd.acclimationlow temperaturenitrogen uptakespecific leaf area2015-0610.1111/pce.12460