Age-dependent variations in transcriptional response to wounding and gibberellic acid in a higher plant.

The reaction of potato tuber tissue upon wounding and gibberellic acid (GA3) treatment is strictly dependent on the tuber age. Young, rapidly growing tubers decline both chromatin-bound, DNA-dependent RNA polymerase (EC 2.7.7.6) activity and template availability as a consequence of wounding and are not responsive toward GA3. At the onset of dormancy, ripened tubers do not at all respond to wounding or hormones, but later on develop the ability to increase their transcriptional rate and template accessibility, both after injury and treatment with 10(-7) mol l(-1) GA3. The size of the nucleolus and the rRNA content of the ribosomal population follows the same pattern.