Figure 1.

Effect of mechanical impedance on Arabidopsis root morphology and growth. A, Confocal image of primary roots of Arabidopsis grown horizontally (top) or vertically (bottom) on dialysis membrane-covered agar plates. Four-day-old roots were stained in 1 μm FM1-43 dye for 15 min. Images are single confocal sections and representative of three separate imaging runs, with five roots per treatment for each run. The images at the left show the epidermal and cortical cell files of the root meristem, images in the middle are the surface view of images at the left, and images on the right show the root elongation zone. The midpoints of the elongation zone images are approximately 320 and 550 μm away from the root tip, respectively. The asterisk in the top image indicates the root hair initiation zone in mechanically impeded roots. Bar = 100 μm. B to D, Differential response of wild-type seedlings for root length (B), mature epidermal cell length (C), and root diameter (D) grown in the presence or absence of mechanical impedance. Vertical bars = mean ± se. Data are from three to five independent experiments with 10 to 12 seedlings per experiment.