Over-expression of AtCHR23 results in reduced root growth. (A) Seedlings grown for eight days at 23°C, long-day (LD). (B) Mean (± SD) length of the primary root of Columbia wild-type (Col), knockout (atchr23) and two lines over-expressing the genomic copy of AtCHR23. (C) Mean (± SD) length of the primary root of Col wild-type and lines over-expressing the cDNA copy of AtCHR23. For each line, 40 seedlings were measured. Asterisks indicate significant differences from the wild-type: ***, P < 0.001.