Figure 3.

N regulation of AtAMT2 expression. Plants were grown in axenic culture in media containing 20.6 mm NH₄NO₃ and 18.8 mm KNO₃ for 19 d (A), for 16 d followed by transfer to a similar medium lacking N for 3 d (B), followed by addition of 1 mm nitrate for 30 min (C) or 1 h (D). Twenty micrograms of total RNA from roots and shoots was loaded in each lane. Hybridization was done with a random-primed full-length AtAMT2 cDNA. Equal loading of RNA was confirmed with a probe to the constitutively expressed gene elF4a.