GMO plum with sharkavirus (Plum pox potyvirus) resistance has been given the trade name HoneySweet. Questions may be asked about health risks. For example, the change could lead to changes in the digestive system if it is eaten. Ethical questions can be asked about what happens if it has changed taste and sweetness. Environmental questions can be asked such as: will this be able to cross with non-GMO plants and take away from the orchard's integrity.
Sharkavirus is a virus disease of Prunus in Europe and around the Mediterranean. The disease was first reported observed in North America in 1999 on peaches (Prunus persica) from a warehouse. The disease has been recorded as an invasive disease species that can cause sharkavirus disease on peaches, apricots, cherries and other stone fruits, as well as plums. PPV was first reported in Bulgaria in 1932. Fruits with a stone in them are those susceptible to sharkavirus.
A protein coat gene originating from the sharkavirus itself has been inserted. This sharkavirus gene has been used to give plum trees (Prunus domestica) resistance to the sharkavirus. The inserted gene is Ppv-cp gene (Plum polypox virus coat protein gene). This is a gene inserted to form pathogen-derived resistance. The resistance is RNA-mediated. This means that the inserted gene originates from pathogenic sharkavirus. RNA from the inserted ppv-cp gene will stop the development of the disease after plant infection. The RNA from the inserted DNA will bind to the parts of the viral RNA that should code for a protein coat and stop them, by binding themselves, from coding for a protein coat.
Genes from sharkavirus and Escherichia coli were inserted into a plasmid in a bacterium (Agrobacterium tumefaciens) for further development in the bacterial culture. Next, A. tumefaciens was used to inject this plasmid construct into plum germ cells. Germ cells with successful uptake and integration of these genes were selected by selection methods with antibiotics that only the genetically modified plums could survive.
Three new genes were inserted, all foreign to plum plants. These inserted genes are: ppv-cp, nptII, uidA. These three genes are linked together on a plasmid in a bacterial culture and injected by these bacteria into plant cell culture. This is so that only those plant cells with both inserted genes for smallpox virus resistance, antibiotic resistance, and enzymes to form color in the test can be selected for further development into plum trees with sharkavirus resistance. Plum trees and plums with sharkavirus resistance will probably develop a blue color in the test.
Sharkavirus is taken up and transported by aphids that sting plants and suck up the virus from liquid in the plant cells to leaves and stems. Aphids can then carry the virus when they fly away from an infected plant and infect other plants when they land on them and sting again with their proboscis. The genetically modified plum line (ARS-PLMC5-6) that is resistant to this virus has been developed. There is progress in developing sharkavirus resistance through breeding. Several different genes contributing to sharkavirus resistance in Prunus species have been identified in different Prunus species, such as apricot (Prunus armeniaca) as well as plum (Prunus domestica).
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