Lignin content determined by staining. Leaf and stem sections of WT and transgenic lines (Vvpgip1 line 37 and 45) expressing the Vvpgip1 transgene. a. Sections corresponding smaller parts of the leaf were stained with potassium permanganate and studied by transmission electron microscopy according to . Lignin in the cell walls stain darker in the transgenic lines. b. Stem sections were hand cut with a razor and stained with a solution of phloroglucinol according to Ruzin . The intensity of the pink-red stain indicates increased lignin deposition in the secondary xylem. Stem sections were taken from the same internode of plants of the same growth stage; leaves for embedding and sectioning were from the same position on plants of the same age (6-8 leaf stage).