Figure 2.

Determination of the experimental conditions. a, Effect of cutting the stem on pra2 protein levels. Total proteins from the stem (1.0 cm from the top of the hook) were extracted, separated by SDS-PAGE, and probed with anti-pra2 protein IgG. The same amount of protein (30 μg) was put in each lane. Six-day-old seedlings grown in darkness (lane 1) were irradiated with white light for 12 h (lane 2). Stem sections (1.0 cm from the top of the hook) of the 6-d-old seedlings were cut and kept in darkness for 12 h on wet cotton (lane 3). The growing zone of etiolated 6-d-old seedlings were bombarded with gold particles and kept in darkness for 12 h (lane 4). b, Effect of pra2 upstream fragment on the reporter-enzyme activity in stems of intact plants and sections. The PL1 construct was introduced into the growing zone of intact etiolated stem (left) or stem section (1 cm from the top of the hook; right) by particle bombardment with the 35S-GUS construct as the internal standard. Reporter-enzyme activity was measured after 12 h of darkness (D) or 12 h of white-light irradiation (L). Relative activity was defined in “Materials and Methods,” and the average of PL1 in darkness was taken to be 100. Values are the means of at least four independently bombarded samples with error bars representing se (n ≥ 4). c, Comparison of reporter-gene expression in different parts of intact stem. PL1 construct was bombarded into the indicated parts, and the reporter-enzyme activity was measured as described.