Figure 5.

TRM4B Is Required for Primary Root Growth Elongation in Young Seedlings.

(A) Root elongation of 7 DAG wild type (Col-0) and two TRM4B T-DNA mutants, trm4b-1 and trm4b-2, grown on 0.5× MS medium with 1% sucrose. Bar = 1 cm.

(B) Graph of primary root growth measurements over time in the wild type and trm4b-1 and trm4b-2 mutants.

(C) Confocal images of 7 DAG wild-type and trm4b-1 root tips stained with propidium iodide. White arrowheads indicate the position of the quiescent center, and yellow arrowheads indicate the first rapidly elongated cell in the cortical layer marking the end of the meristem. Insets (50-µm length) are enlarged images of the boxed areas showing cortical cells in the meristematic zone marked with asterisks. Bar = 100 µm.

(D) to (F) Root apical meristem size (D), cell number (E), and cell length (F) of wild-type and trm4b-1 mutant plants.

(G) Activity of CYCB1;1:GUS reporter in the root meristems of wild-type and trm4b-1 plants, detected by GUS staining. Bar = 100 µm. Error bars in (D) to (G) indicate the se of the mean (*P < 0.05, Student’s t test; n ≥ 8 seedlings).