pAtGH3.15:YFP expression in Arabidopsis roots. Seedlings expressing YFP driven by the promoter region of AtGH3.15 (pAtGH3.15:YFP) were grown under continuous light for the indicated number of days at 22 °C and imaged using a Leica upright microscope. A and B, 2-day-old seedlings; C–E, 4-day-old seedlings; F, 5-day-old seedlings; G–I, 9-day-old seedlings; J, 11-day-old seedlings; K, 16-day-old plants; L, 20-day-old plants. Scale bar, 250 μm in A–K and 100 μm in L. Arrows in D and G indicate the root/shoot junction, and the arrow in F indicates the root tip.