AN APPLE POLYPHENOL OXIDASE CDNA IS UP-REGULATED IN WOUNDED TISSUES

A full-length cDNA clone encoding apple (Malus domesticus) polyphenol oxidase (PPO) was isolated from a fruit peel cDNA library. Southern an alysis indicated that apple PPO is encoded by a divergent multigene fa mily. BY northern analysis, PPO mRNA was only detected in a fruit samp le taken one week after full bloom. PPO mRNA accumulated in wounded ti ssues, and also in peel tissue showing the symptoms of superficial sca ld, a post-harvest disorder. The induction of PPO mRNA provides the fi rst evidence for transcriptional control of PPO expression after wound ing or the manifestation of a physiological disorder.