GUS histochemical staining
For histochemical analysis of GUS activity, the roots of 3-day-oldpDR5:GUS and pCYCB1:GUS marker lines were incubated overnight at 37 ℃ in a GUS reaction buffer after 6 d of co-cultivation with SQR9. The stained roots were cleared using the method of Malamy and Benfey (1997). For each marker line and for each treatment, at least 12 transgenic plants were analyzed. A representative sample was chosen and photographed using Leica DM2500 microscope.