High transformation efficiency in plum (Prunus domestica L.):: a new tool for functional genomics studies in Prunus spp.

An improved Agrobacterium-mediated transformation protocol for plum (Prunus domestica L.) hypocotyl slices was developed based on the addition of 2,4-D to the co-cultivation medium. This method increased transformation efficiency up to 10 x (42%) over previous reports with an average efficiency of 25% of hypocotyl slices producing transgenic plants. Timing of each step in the protocol was optimized producing self-rooted transgenic plants in the greenhouse in approximately 6 months. In order to test the system for its utility in functional genomic studies, we developed two hairpin constructs using a fragment of the peach (P. persica) Phytoene desaturase (PDS) gene. When A. tumefaciens with these constructs was used for targeted post-transcriptional gene silencing (PTGS), approximately 50% of the transformed plums were knockout PDS gene plants. The easy and efficient plum transformation protocol that we report here can be readily used for functional genomics studies in Prunus specifically, and Rosaceae and other woody species in general.