Fig. 8.

Movement of transgenic StBEL5 RNA from the 35S:BEL5 transgenic scion into stocks of wild-type (WT) Désirée and transgenic lines overexpressing StPTB1 (PTB1-OE line 9–12), StPTB6 (PTB6-OE line 10–1), and a line that suppresses both StPTB1 and StPTB6 (PTB1/6-AS line 23). All transgenic lines are from the potato cv. Désirée. Heterografts were performed in vitro and maintained in tissue culture for 3 weeks, and then moved to soil for 3 weeks before harvesting. For quantification, RNA was extracted from either leaves of the scion or stolon tips (new tubers) of the stocks, and qRT–PCR was used to calculate the relative amounts of transgenic StBEL5 RNA that trafficked across the graft union and down into stolon tips. Each sample was measured and normalized against StActin8 RNA. RNA values were calculated as the 2^−ΔΔCt value relative to the mean values obtained from leaf samples of the 35S:BEL5 scion. Standard deviations of the means of two biological replicates with two technical replicates are shown, with two and three asterisks indicating significant differences from the WT stock stolons (P<0.01 and P<0.001, respectively) using a Student’s t-test.