Figure 7.

Analysis of Cell Division Patterns for Phloem Sieve Element Development in the Wild Type, nars1 and snd2.

(A) to (P) Analysis of division patterns of phloem SE precursors in the roots of the wild type (WT; [A] to [D]), nars1 ([E] to [H]), snd2 ([I] and [L]) and the nars1 snd2 double mutant ([M] to [P]). Analysis of cell division patterns using consecutive cross-sections in WT ([A] and [B]), nars1 ([E] and [F]), snd2 ([I] and [J]) and snd2 nars1 double mutant ([M] and [N]) and resulting cell organization in the root differentiation zone ([C], [G], [K] and [O]). SE-ENOD immunolocalization shows two differentiated phloem SEs in WT (D) and snd2 (L) but only one in nars1 (H) and nars1 snd2 (P).

(Q) to (S) Confocal images of wild-type (Q), nars1 (R), and snd2 (S) root meristems. Phloem precursor cells in the wild type and snd2 divide twice, whereas that in nars1 divides only once. Yellow arrowhead, xylem axis; green arrowhead, pole with two phloem SEs; orange arrowhead, pole with one phloem SE; red arrow, ACD of the procambium-phloem initial; white arrow, ACD of the phloem SE initial; Scale bar = 20 μm.