Expression of GUS driven by the AtXYL1 promoter. A, Root tip from a 12-d-old plant grown on soil. Bar = 50 μm. B, Roots from a 12-d-old plant. C, Rosette leaves from a 21-d-old plant. D, First-pair leaf from a 12-d-old plant. Bar = 100 μm. E, Stage 12 flower bud. Bar = 100 μm. F, Flowers at different stages. G, Upper part of an elongated silique. H, Base of a developing silique. Bar = 100 μm. I, Young stem and pedicels.