Fig. 8.

CIPK9 expression, primary root growth and cellular NH₄⁺ levels in plants produced by crosses between IDD10 and CIPK9 OX. (A) Levels of CIPK9 expression in wild-type (WT), IDD10, idd10/CIPK9 OX and CIPK9 OX determined using qRT–PCR. Levels of CIPK9 mRNA were normalized against the level of UBIQUITIN mRNA in the same samples. Data are means ± S.E. (n = 3); different letters indicate significant differences between results (P < 0.05). (B) Appearances of wild-type (WT), idd10, idd10/CIPK9 OX and CIPK9 OX seedlings after growth for 4 d in a nutrient solution with either NO₃^– or NH₄⁺ as the sole N source (Supplementary data Table S1). Scale bar = 1 cm. (C) Measurements of primary root length of plants grown as in (B). (D) Levels of cellular NH₄⁺ levels in roots of seedlings grown for 4 d in a nutrient solution with either NO₃^– or NH₄⁺ as the sole N source. Data shown in (C) and (D) are means ± s.e. (n >10 plants per line); different letters indicate significant differences between results (P < 0.05).