'HoneySweet' (C5), the first genetically engineered Plum pox virus-resistant plum (Prunus domestica L.) cultivar

Authors: Scorza, Ralph; RAVELONANDRO, MICHEL - Institut National De La Recherche Agronomique (INRA); Callahan, Ann; ZAGRAI, IOAN - Fruit Research & Development Station Bistrita - Romania; POLAK, JAROSLAV - Crop Research Institute - Czech Republic; MALINOWSKI, TADEUZ - Research Institute Of Horticulture; CAMBRA, MARIANO - Valencian Institute For Agricultural Research; LEVY, LAURENE - Animal And Plant Health Inspection Service (APHIS); Damsteegt, Vernon; KRSKA, BORIS - Mendel University; Cordts, John; GONSALVES, DENNIS - Retired ARS Employee; Dardick, Christopher - Chris

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2016
Publication Date: 5/1/2016
Citation: Scorza, R., Ravelonandro, M., Callahan, A.M., Zagrai, I., Polak, J., Malinowski, T., Cambra, M., Gonsalves, D., Dardick, C.D. 2016. 'HoneySweet' (C5), the first genetically engineered Plum pox virus-resistant plum (Prunus domestica L.) cultivar. HortScience. 51(5):601-603.

Interpretive Summary: 'HoneySweet' plum was released by the U.S. Department of Agriculture, Agricultural Research Service, to provide U.S. growers and P. domestica plum breeders with a high fruit quality plum cultivar resistant to Plum pox virus (PPV). PPV is the most serious disease of plums and other stone fruits such as peaches, cherries, and apricots. This virus disease causes fruit to be unmarketable and trees to decline. PPV, first found in Europe, has been spreading world-wide. It entered into the U.S. in 1999 and caused catastrophic losses to peach and plum growers in Pennsylvania. It was eradicated in 2009 but remains a serious threat to U.S. stone fruit production. 'HoneySweet' has been genetically engineered to be resistant to PPV. Its high level of resistance has been verified in over 20 years of evaluation in Europe under severe disease pressure. Based on its environmental and health safety and high level of PPV resistance, 'HoneySweet' has been approved for cultivation in the U.S. by all agencies that regulate genetically engineered crops. 'HoneySweet' produces high quality flavorful fruit that contribute to a healthy diet. 'HoneySweet' can be used in conventional breeding to develop new PPV resistant varieties

Technical Abstract: ‘HoneySweet’ plum was released by the U.S. Department of Agriculture, Agricultural Research Service, to provide U.S. growers and P. domestica plum breeders with a high fruit quality plum cultivar resistant to Plum pox virus (PPV). ‘HoneySweet’ was developed through genetic engineering utilizing the PPV coat protein (CP) gene as the source of resistance. Resistance to PPV in ‘HoneySweet’ is a result of RNA interference resulting from an inverted repeat of the PPV-CP insert in the plum genome. ‘HoneySweet’ also contains the transgenes for kanamycin resistance (NPTII) and the reporter gene uidA (GUS). The PPV-CP transgene imparts a high level of resistance to PPV. In over 18 years of field testing in European test sites with high PPV infection pressure, no trees of ‘HoneySweet’ have been directly infected with PPV by the natural aphid vectors. When 'HoneySweet' is bud-graft inoculated with plum pox virus, it supports only a very low level of virus near the point of graft-inoculation and is symptomless or shows only transient, very mild symptoms and limited systemic spread of virus. ‘HoneySweet’ is also highly resistant to black knot disease caused by the fungus Apiosporina morbosa. It appears to have inherited this resistance from ‘Bluebyrd’, its seed parent, which is also highly resistant to black knot (Scorza and Demuth, 2015). ‘HoneySweet’ fruit are large and sweet, mostly freestone, firm and attractive. The tree is productive, vigorous, with a moderate level of fruiting spur development and with an upright growth habit. ‘HoneySweet’ is self-sterile and requires a compatible pollinator. ‘HoneySweet’ was deregulated by the U.S. Animal and Plant Health Inspection Service (APHIS) in 2007, (http://www.aphis.usda.gov/brs/aphisdocs/04_26401p_ea.pdf), reviewed by the U.S. Food and Drug Administration (FDA) in 2009 (http://www.fda.gov/Food/FoodScienceResearch/Biotechnology/Submissions/ucm155594.htm), and registered by the Environmental Protection Agency (EPA) in 2011 (http://www.epa.gov/opp00001/chem_search/reg_actions/registration/decision_PC-006354_7-May-10.pdf).