Figure 2.

Expression of K⁺ transporter-coding genes is enhanced by K⁺ starvation through an ammonium-sensitive and an ammonium-insensitive pathway. A, Accumulation of HvHAK1 and HvHAK1b transcripts in 1-week-old plants grown with or without K⁺ since germination (n = 3). ddCt corresponds to the difference in transcript accumulation between the presence of K⁺ (control condition) and its absence (no K⁺ added). Asterisks denote significant effects of K⁺ deprivation. B and C, Effects of the presence or absence of K⁺ and NH₄⁺ (100 μm and 5 mm, respectively) during a 3-d period on the accumulation of HvHAK1 and HvHAK1b transcripts (n = 6). Error bars represent se. Different letters indicate significantly different values (P < 0.05 for A and B, P < 0.001 for C).