It has previously been shown that dynamic acclimation of photosynthesis is essential to increase plantsâ fitness under variable light environments. Acclimation can be defined as a process where organisms adjust gene expression, protein synthesis and metabolic properties to accustom or become accustomed to a new environment and to improve resource use efficiency and fitness. In previous study, acclimation is mediated by a glucose-6-phosphate/phosphate translocator, GPT2. This study examined whether plants lacking GPT2, which are defective in acclimation to increased light, are more susceptible to oxidative stress. To understand this, we used the model plant of Arabidopsis thaliana (accession Wassilewskija (Ws-2)) and compared this to mutants lacking GPT2. Plants were grown at low light (100 Î¼mol mâ2 sâ1) and high light (400 Î¼mol mâ2 sâ1) for 7 weeks. For acclimation experiments, a set of plants from low light was transferred to 400 Î¼mol mâ2 sâ1 for 7 days. Subsequently, plants were exposed to a sudden shock with 1000 Î¼mol mâ2 sâ1 for up to 2 hours. To evaluate acclimation to naturally variable conditions, an experiment was performed in a glasshouse throughout the winter season 2015/2016. Transcriptomic and proteomic from growth room studies showed that gpt2 plants induced more stress related genes relative to WT. Biochemical and physiological analyses also showed that the gpt2 plants had significantly greater activity of ascorbate peroxidase (APX), total peroxidase (GPOX) and superoxide dismutase (SOD) and significantly lower values of Fv/Fm. Meanwhile, in glasshouse experiments, gpt2 plants had a lower photosynthetic capacity than the WT. This study concludes that acclimation to HL is necessary to protect plants from oxidative stress as well as to promote better tolerance when grown in fluctuating light and temperature in the glasshouse.