Fig. 1.

Root system of A. tequilana. Root system of 2-year-old plant (a) and 6-year-old plants (b, c). In mature roots (red roots, d), high accumulation of lignin in cortex (e–g) and epidermis/exodermis (e, h, i) was revealed by staining with basic Fuchsin, and imagined under light microscopy (f) and confocal microscopy (g–i). This gradual lignin deposition from young (j) to mature roots (k) alters viability out-layers cells. A slight lignin deposition (g) is also observed in vascular tissues (g, l). Diagram of a cross section of agave root was re-drawn of North and Nobel 1995