Figure 2.

Transcript Accumulation of the Senescence-Associated Genes SAG12 and SAG13 in Wild-Type and old5 Mutant Plants.

The relative levels of SAG12 and SAG13 were examined by real-time RT-PCR, using ACT2 as an internal control, of first rosette leaves of 21- to 33-d-old plants (old5, gray bars; wild type, black bars). For SAG13, the relative transcript levels detected in the wild-type plants were arbitrarily assigned a value of 1 after normalization to the ACT2 samples. For SAG12, the relative transcript level detected at day 30 in old5 was set at 1 and used for comparison with day 33. The values shown are means of three repeats ± sd (indicated by error bars). Experiments were repeated and showed comparable results. Asterisks indicate statistical significance versus the wild-type control in each case (* P < 0.05, Student's t test).