|POLAK, JAROSLAV - Crop Research Institute - Czech Republic|
|KUMAR, JIBAN - Crop Research Institute - Czech Republic|
|KRSKA, BORIS - Mendel University|
|RAVELONANDRO, MICHEL - Institut National De La Recherche Agronomique (INRA)|
Submitted to: Plant Protection Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2012
Publication Date: 12/12/2012
Citation: Polak, J., Kumar, J., Krska, B., Scorza, R., Ravelonandro, M. 2012. Biotech/GM crops in horticulture: plum cv. HoneySweet resistant to plum pox virus. Plant Protection Science. 48:S43-S48.
Interpretive Summary: Genetic engineering offers the promise of disease control through non-chemical means. This technology could have important uses for tree fruits which are subject to a number of difficult to control disease problems including virus diseases. One of the most devastating virus diseases affecting stone fruit trees (plums, apricots, peaches, cherries) is plum pox virus (PPV) which is an exotic disease organism that has recently invaded the U.S. We have developed PPV resistant plum trees through genetic engineering. To test for the strength and durability of resistance to PPV, and to test for resistance to PPV in the presence of other stone fruit viruses, field tests were conducted in the Czech Republic, a country that has a very serious high level of PPV infection in its plum orchards. After 10 years of field testing our PPV resistant plum tree named 'HoneySweet', we found that no 'HoneySweet' trees could be naturally infected with PPV (by the aphid insect vector) even though most of the surrounding non-genetically engineered trees became infected. Graft inoculation of ‘HoneySweet’ using buds from PPV infected trees showed that a mild infection occurred in ‘HoneySweet’ trees only near the site of the infected bud grafts. We also showed that even in the presence of other plum virus diseases which could infect ‘HoneySweet’, it remained resistant to PPV, and fruit production and quality were not affected. These tests showed conclusively that the genetically engineered plum variety, 'HoneySweet', is highly resistant to PPV and that the resistance has been durable for nearly a decade so far. This work shows the great potential of genetic engineering for disease control in fruit trees.
Technical Abstract: Commercialization of Biotech crops started in 1995. By 2011, genetically modified (GM) crops were grown world-wide on 160 million ha. Only 114.507 ha of GM crops were grown in Europe, of that, 114.490 ha were Bt maize and 17 ha were potato for industrial starch production. Currently, developing countries account for close to 50 percent of global Biotech crop production. The U.S. is the lead producer of Biotech crops with 69 million ha, 43 percent of global. GM soybean remains the dominant crop, followed by Bt maize, cotton, and canola. Golden Rice is advancing towards the completion of its regulatory requirements. Not only field crops, but also horticultural transgenic crops are under development and are beginning to be commercialized. Genetic engineering has the potential to revolutionize fruit tree breeding. The development of transgenic fruit cultivars is in progress. Over the past 20 years, an international public sector research team has collaborated in the development of ´HoneySweet´ plum which is highly resistant to Plum pox virus (PPV) the most devastating disease of plum and other stone fruits. ´HoneySweet´ was deregulated in the U.S. in 2011. ´HoneySweet´ (aka ‚C5) has been evaluated for ten years (2002-2011) in a regulated field trial in the Czech Republic for resistance to PPV, Prune dwarf virus (PDV), and Apple chlorotic leaf spot virus (ACLSV), all serious diseases of plum. Even under high and permanent infection pressure produced through grafting, PPV has only been detected in ‘HoneySweet’ trees in several leaves and fruits situated close to the point of inoculum grafting. The lack of infection spread in ´HoneySweet´ demonstrates its high level of PPV resistance. Co-infections of PPV with PDV and/or ACLSV had practically no influence on the quantity and quality of ‘HoneySweet’ fruit which are large, sweet, and of high eating quality. In many respects, they are superior to fruit of the well-known cultivar‚ 'Stanley'. Many fruit growers and fruit tree nurseries in the Czech Republic are supportive of the deregulation of ´HoneySweet´ plum to help improve plum production and control the spread of PPV.