Figure 6.

RNA blot analysis of WT and chl1-5 plants. Whole seedlings were grown in liquid culture with 12 mM ammonium succinate at pH 6.5 for 5 days as described in Materials and Methods. At time zero, equal volumes (2 ml) of fresh medium containing 0.2 mM KNO₃ (to give a final nitrate concentration of 0.1 mM; lanes 1–6 & 11–14) or 0.2 mM KCl (final concentration of 0.1 mM; lanes 7–10) were added to the culture. At times indicated in the figure, seedlings were rinsed with distilled water, blotted dry, and frozen in liquid nitrogen. Total RNA was prepared from whole seedlings, analyzed on 1.4% formaldehyde agarose gels, blotted onto a filter, hybridized with radiolabeled CHL1 cDNA (Top), NRT2–1 genomic DNA (Middle), or β-tubulin cDNA (Bottom), and autoradiographed.