Quality traits: NewLeaf^TM anti-bruise potatoes (under development)

The production of NewLeaf^TM ‘anti-blackspot’ bruise potatoes has also involved down-regulation of a tuber-expressed PPO gene using a tuber-specific promoter. Lines of Russet Burbank that showed >70% reduction in PPO activity were again almost devoid of any bruise symptoms under field conditions (Fig. 9.2). The construct used has been optimised to increase the frequency of lines showing >70% reduction in PPO activity. This involved cloning a full length, tuber-specific PPO gene and testing three proprietary tuber-specific promoters in the cultivar Ranger Russet. All optimised constructs produced complete elimination of PPO and a corresponding commercial level of black spot bruise resistance over three generations of replicated field trials.

At the time when NatureMark’s^® business was closed, commercial line selection was in progress using transgenics with combined black spot bruise and glyphosate resistance.