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. 2002 Apr;14(4):833–845. doi: 10.1105/tpc.010402

Figure 2.

Figure 2.

Confocal Imaging of MT Arrays in Wild-Type, ton2-14 Weak Allele, and ton2-13 Strong Allele Seedlings Expressing a GFP-MBD Fusion (Marc et al., 1998).

(A), (D), (G), and (J) Wild type.

(B), (E), (H), and (K) ton2-14 weak allele.

(C), (F), (I), and (L) ton2-13 strong allele.

(A) to (I) MT arrays in dividing cells from leaf primordia of 7-day-old seedlings. In wild-type cells, MTs are first organized in a PPB encircling the cell at the cortex (arrows in [A]). In ton2 mutant premitotic cells, PPBs are never observed, and only perinuclear MTs are visible (asterisks in [B] and [C]). MTs then organized in the mitotic spindle during metaphase (s in [D] to [F]) and in the phragmoplast during telophase (p in [G] to [I]). Spindles and phragmoplasts of ton2 mitotic cells are similar to those in the wild type. However, guidance of the phragmoplast is largely affected in the mutant background. Note, for example, that (F) and (I) show images of the same cells taken 25 min apart: a spindle with a transverse metaphase plate is followed by a phragmoplast that appears to show erratic growth along a longitudinal plane. (A), (F), and (I) show stacks of five (A), seven (F), and nine (I) optically sectioned images taken 1 μm apart. (B) to (E), (G), and (H) show single optical sections. Bars = 10 μm.

(J) to (L) Interphase MT arrays in epidermal hypocotyl cells of 7-day-old seedlings. Images were taken from the central part of the hypocotyl. In wild-type cells (K), MTs are perpendicular to the hypocotyl and the cell elongation axis (arrows in [J] to [L]). In weak alleles (ton2-14 [K]), cells undergo slight elongation parallel to the hypocotyl axis, which is not observed in strong alleles (ton2-13 [L]). In both mutant alleles, MTs show essentially parallel organization in hypocotyl cells. In the weak allele (K), MTs are in oblique or longitudinal orientation with respect to the hypocotyl axis, whereas the strong allele does not show any preferential MT orientation (L). Arrows in (J) to (L) indicate the axes of hypocotyl growth. (J) to (L) show stacks of 5 (K), 8 (L), and 11 (J) optically sectioned images taken 2 μm apart. Bars = 50 μm.