Two rootstocks from the Giessen (GiSelA) series of dwarfing cherry (Prunus sp.) rootstocks, GiSelA (Gl) 5 (syn. 148/2) and Gl 6 (syn. 148/1), are becoming commercially important and five other Giessen cherry rootstocks are being evaluated for horticultural traits. Since Gl 5 and Gl 6 are morphologically similar, a DNA fingerprinting project was undertaken to identify molecular markers that could be used by the nursery industry to differentiate these two rootstocks. The project was extended to include six additional Giessen rootstocks of varying pedigrees. Fourteen DNA primer pairs were tested for their ability to differentiate among the eight rootstocks. None of the primer pairs could differentiate all eight rootstock selections; however, three primer pairs could differentiate all but two selections. Two primer pairs, PMS 15 and PceGA59, were identifled as the most suitable for high throughput screening of Gl 5 and Gl 6 due to the simplicity and the size of the base pair differences among the Polymorphie fragments. These results demonstrate the utility of molecular markers to differentiate the Giessen cherry rootstocks.
