Fig. 6.

Primary root cell architecture in Landsberg erecta (Ler), yda1 and ΔNyda1 Arabidopsis plants after staining of living roots with membrane marker FM4-64 and CLSM. (a–d) Surface (a, c) and central (b, d) optical sections of a Ler root. (a) Overview and (c) higher magnification of the epidermis showing the orderly arrangement of epidermal cells in linear files resulting from symmetric periclinal and anticlinal divisions in Ler. (b) Overview and (d) higher magnification of an orderly structured stem cell niche region in Ler. (e–h) Surface (e, g) and central (f, h) optical sections of a yda1 root at similar planes as shown in (a)–(d). (e) Overview and (g) higher magnification of the epidermis showing disturbed cell division planes. Similarly, in central sections (f, h) the stem cell niche is disordered with ectopic cell divisions and displaced cell division planes. (i–l) Surface (i, k) and central (j, l) sections of a ΔNyda1 root. (i, k) Epidermal cell divisions are severely disordered with aberrant, oblique cell division planes. The stem cell niche (j, l) shows similarly defective organization with ectopic cell divisions and altered cell division planes as in yda1. (m) Quantification of oblique cell walls graphically depicting mean ± SD for Ler (N = 610), yda1 (N = 645) and ΔNyda1 (N = 596). Cell walls were evaluated in 10 independent plants in each case. White asterisks in (b, f, j) mark root cap layers. ***, P < 0.001. Bars: (a, b, i, j) 50 μm; (e, f) 20 μm; (c, d, g, h, k, l) 10 μm.