Development and Regulation of the Plum Pox Virus Resistant Transgenic Plum ‘HoneySweet’

Genetic engineering (GE) can target specific genetic improvements and allow for the development of novel, useful traits. In spite of the potential utility of GE for fruit tree improvement, the technology has not, to date, been widely exploited for variety development due, in part, to the reticence of researchers to become involved in the regulatory process. Over the past 20 years an intensive international research project focused on the development of GE resistance to Plum pox virus (PPV) the causative agent of Sharka, one of the most destructive diseases of plum and other stone fruits. This effort resulted in the development of ‘HoneySweet’ plum, a GE variety that has proven to be highly resistant to PPV, as demonstrated in over 15 years of field testing in the U.S. and Europe. In order to make this variety available to breeders and growers in the U.S., dossiers were submitted to the U.S. regulatory agencies. This process ultimately led to the regulatory approval of ‘HoneySweet’ in the U.S. The work with ‘HoneySweet’ demonstrates that the regulatory process, while a significant effort, can be successfully navigated by public institution researchers. Nevertheless, the few examples of such success demonstrate a need for public institutions to find ways to encourage, support and reward researchers who pursue deregulation efforts. The long-standing successes of virus control in squash and papaya, and the current work with plum demonstrate the power and the safety of GE for specialty crop improvement. The commitment of researchers, institutional support, clear, science-based regulatory frameworks that build upon a developing knowledge base, industry support, and public outreach are components that are now necessary to move this technology forward to improve agricultural production and its sustainability.