Transient gene silencing
OSF has a project to better understand the opportunities to use transient gene silencing to modify the expression of genes in apple cultivars. Transient gene silencing is not genetic modification in the traditional sense. Rather it is the result of combining two different genotypes through grafting. In our initial studies, commonly available commercial cultivars of apple, such as Golden Delicious and Granny Smith (aka "the recipient"), are grafted on to rootstocks and/ or interstems (aka "the donor") that have been genetically modified to suppress the expression of PPO (aka "the trait"). The trait can be transferred from the donor to the recipient though small interfering RNA (siRNA) that migrate through the plant. The result is the production of nonbrowning fruit from the non-transgenic recipient. OSF has evidence that this transient gene expression can be triggered in the right conditions.
In the future, this technology could be used to transfer a wide variety of traits (disease resistance, agronomic improvements, etc) from a variety of both genetically modified or traditionally bred donor rootstocks. It has the important advantage that a single donor rootstock could be used to improve any number of commercial apple cultivars, rather than having to modify each new apple cultivar one at a time.