Expression of GPT2 during early seedling development on glucose. Seeds were sterilized, stratified, sown and transferred to light as for seedling development assays, with the inclusion of 4 % glucose or PEG-8000 of the equivalent osmotic potential to the medium. GPT2 expression was examined in seedlings after transfer to light, with samples of 200–250 seedlings flash-frozen in liquid nitrogen at the end of each photoperiod. Frozen seedlings were stored at −80 °C. Fold changes shown were calculated relative to levels of ACT2 expression and are displayed relative to the expression level on half-strength MS at each time point. Shaded areas represent dark periods and unshaded areas represent photoperiods. Data expressed relative to UBC are qualitatively identical. Error bars represent ±1 s.e. Plants grown on half-strength MS only, grown on half-strength MS with PEG-8000 with an equivalent osmotic potential to 4 % glucose, and grown on half-strength MS with 4 % glucose are as indicated in the key.