Figure 7.

NtTCTP and NTHK1 regulate root growth and development. A, Growth of different tobacco lines on vertical one-half-strength MS plates for 20 DAS. Bar = 1.5 cm. B, Primary root length of various lines at the early stage of root development; 7-DAS seedlings were transferred to new one-half-strength MS plates and placed vertically for continuous growth. Seedlings were photographed every day until 20 DAS for examination of root parameters. The data are expressed as the means ± se from three independent experimental groups (n = 12). C, Lateral root numbers in different plant lines. Others are the same as in B. D, Measurement of the mitotic index of root tips from 7-DAS seedlings. The data are expressed as the means ± se from three independent experimental groups (n = 6). Asterisks indicate significant differences from the wild type (WT; Student’s t test). *, P < 0.05; **, P < 0.01.