Figure 5.

Light/dark regulation of GUS mRNA expression under TRX f and TRX m promoters. Transgenic plants carrying complete promoter constructs (f1-GUS or m1-GUS) or a truncated promoter (f2-GUS, m2-GUS, m3-GUS, m4-GUS, or m5-GUS) were subjected to a 12-h-day/12-h-night photoperiod, and mRNA levels of the GUS-encoding gene were determined in leaves by semiquantitative RT-PCR as described in “Materials and Methods.” A, GUS expression under the TRX f promoter. B, GUS expression under the TRX m promoter. Samples were harvested at midday and midnight from 20-d-old plants. Values are the average of three determinations of two cDNA preparations.