“Experimental procedures exploiting RNAi approaches allowed the generation of Prunus necrotic ringspot virus (PNRSV) resistant individuals of a cherry rootstock217. Grafting of these individuals demonstrated small RNA transport from rootstock to scion, resulting in “Emperor Francis” scions becoming resistant to PNRSV218. In this way, the use of Prunus genotypes currently suitable for genetic transformation can be proposed as small RNA generators (donors) for systemic transmission of resistance through transgrafting to compatible scions from different genetic backgrounds, directing either systemic sRNA-directed gene silencing or sRNA-directed DNA methylation.”
See:
A related note, though there is no mention of RNA interference.
Plant Mol Biol. 2003 Nov; 53(4): 493-511.
Rootstock effects on gene expression patterns in apple tree scions.
Jensen PJ, Rytter J, Detwiler EA, Travis JW, McNellis TW
Like many fruit trees, apple trees (Malus pumila) do not reproduce true-to-type from seed. Desirable cultivars are clonally propagated by grafting onto rootstocks that can alter the characteristics of the scion. For example, the M.7 EMLA rootstock is semi-dwarfing and reduces the susceptibility of the scion to Erwinia amylovora, the causal agent of fire blight disease. In contrast, the M.9 T337 rootstock is dwarfing and does not alter fire blight susceptibility of the scion. This study represents a comprehensive comparison of gene expression patterns in scions of the ‘Gala’ apple cultivar grafted to either M.7 EMLA or M.9 T337. Expression was determined by cDNA-AFLP coupled with silver staining of the gels. Scions grafted to the M.9 T337 rootstock showed higher expression of a number of photosynthesis-related, transcription/translation-related, and cell division-related genes, while scions grafted to the M.7 EMLA rootstock showed increased stress-related gene expression. The observed differences in gene expression showed a remarkable correlation with physiological differences between the two graft combinations. The roles that the differentially expressed genes might play in tree stature, stress tolerance, photosynthetic activity, fire blight resistance, and other differences conferred by the two rootstocks are discussed.
http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=15010615&dopt=AbstractPlus