Fig. 6

Induction of protoxylem tracheary element differentiation and secondary wall deposition in the epidermal cells. Transient overexpression of PdbVNS07 (VND-, NST/SND- and SMB-related protein), PdbVNS09 or PdbMYB020 fused with the activation domain of the herpes virus VP16 protein in poplar leaves via syringe agroinfiltration resulted in ectopic secondary wall deposition in the epidermal cells. Transiently transformed leaves were detached, stained with basic fuchsin at 10 dpi, and observed with a confocal microscope for secondary walls. a and b. Epidermal cells overexpressing PdbVNS07-VP16, showing transdifferentiation of protoxylem-like vessel elements with annular and spiral thickenings in the cell wall. c and d. Epidermal cells overexpressing PdbVNS09-VP16, showing the ectopic secondary wall deposition. e and f. Epidermal cells overexpressing PdbMYB020-VP16, showing band-like secondary wall thickening. g and h. Epidermal cells overexpressing the control vector pGreenII 62-SK, showing no secondary wall thickening. a, c, e, and g are images of differential interference contrast; b, d, f, and h are images of the basic fuchsin stain. White stars indicated ectopic secondary wall deposition