Starch contents of ss4 plants expressing GS- or SS4-derived proteins. Plants grown for four weeks under 12-h-day/12-h-night cycles were harvested at the end of day (white bars) and end of night (black bars). The mean starch content (± se) for each line is given (n = 4 individual rosettes for Col, ss4, and SS4N-YFP; n = 6 for all other lines). For Col and for ss4, the data in the top and bottom panels are the same. The percentage of starch broken down during the night is indicated.