Figure 2.

Ammonium controls the light induction of ASN2. Seedlings were germinated and grown under a regular day/light cycle on Murashige and Skoog agar plates containing no (A) or 20 mm (B) ammonium for 14 d before being transferred to Murashige and Skoog agar plates containing 20 mm (A) and no (B) ammonium respectively, and grown under continuous light. NaNO₃ was added to ammonium-free medium to maintain an equal molar concentration of nitrogen resource. Samples were collected at time 0, 2, 4, 8, 16, 24, and 48 h (lanes 1-7, respectively) after treatments. Total RNA was extracted from the seedlings as described in “Materials and Methods.” An aliquot of 15 μg of total RNA from each line was loaded onto each lane. Northern-blot analysis was performed as described in “Materials and Methods.”