Identification of robust sugar-responsive genes whose transcripts correlate with changes in glucose, sucrose or glucose-6-phosphate during diurnal cycles in WT plants and pgm, and in an extended night treatment. (a) Correlation coefficients and corresponding p values (x axis, logarithmic scale) were calculated between the transcript levels for each of these genes and the levels of glucose, sucrose, or glucose-6P using a combined dataset, including data obtained from WT and pgm across a night and day cycle, and WT plants transferred to an extended night. The top graphs show the number of genes whose transcripts correlate with glucose (left hand), sucrose (middle) or glucose-6P (right hand) at a significance level. The bottom graphs show the proportion of the genes that correlate with a given metabolite, which are found in a set of 'sugar-responsive' genes (thick line). A set of 1,312 'sugar-responsive' genes was defined by inspection of public domain data for experiments in which sugars were added to carbon-starved seedlings for 3 h, or leaves were illuminated for 4 h in the presence and absence of CO2(see main text for details). The plot also shows a similar comparison against a set of genes that are induced or repressed within 30 minutes by addition of sucrose to starved seedlings (dotted line). Blue lines correspond to positive correlations, red lines to negative correlations. (b) Venn Diagram of sugar-regulated genes correlated to sucrose, glucose and glucose-6-phosphate with a significance level of 0.001 or better. In total, 1,141 of the 1,312 genes correlated with at least one metabolite with a p value < 10-3.