Cellular Phenotype of kob1-1 Hypocotyls and Roots.

(A) and (B) Transverse sections halfway along hypocotyls of 5-day-old dark-grown wild-type (A) and kob1-1 (B) seedlings after Calcofluor staining. Mutant hypocotyls show unaltered anatomy, but all cells show increased radial expansion compared with the wild type. Mutant cell walls are interrupted frequently (arrowheads in [B]). wt, wild type. Bar in (B) = 50 µm for (A) and (B).

(C) to (F) Confocal optical median sections, stained in vivo with FM1-43, of 7-day-old light-grown wild-type ([C] and [D]) and kob1-1 ([E] and [F]) roots. Root meristem ([C] and [E]), elongation zone (D), and mature part (F) are shown. Note the dramatically reduced elongation zone in kob1-1, as shown by the premature appearance of root hairs (arrowheads). Bar in (C) = 50 µm for (C) to (F).

(G) Phloroglucinol staining of 4-day-old dark-grown kob1-1 (left) and wild-type (right) seedlings showing red staining of ectopic lignin in the mutant root.

(H) and (I) Sirofluor staining of 4-day-old dark-grown wild-type (H) and kob1-1 (I) seedlings showing light blue staining of ectopic callose in the mutant.