Histochemical staining of lignin

Inflorescence stems of 8-week-old plants that were >30 cm tall and showed ripeness of the first siliques were cut at the base, segmented into 1 cm pieces, and embedded in 6% agarose in water. Sections of 100 µm thickness were prepared using a Leica VT 1000 S vibratome (Leica Microsystems) and stained with 5% phloroglucinol-HCl solution that was freshly prepared by mixing equal volumes of 10% phloroglucinol (Sigma-Aldrich Inc., St. Louis, MO, USA) in ethanol and 37% HCl. Samples were observed using a Leica DMR HC (Leica Microsystems).