Figure 4.

Northern-blot analysis of members of the HvNRT2 family of genes. Time course effects of pretreating nitrogen-starved plants with 1 mm NO₃⁻ for 0, 3, 6, 9, 12, 24, and 48 h. Twenty micrograms of total RNA was introduced into each lane, probed with HvNRT2.3 internal fragment (which recognizes all known HvNRT2 homologs), and then washed at medium stringency (panel 1). Northern blots were probed with the 25S ribosomal subunit to ensure equal loading of RNA. Northern blots were also probed with specific oligonucleotides directed to HvNRT2.1, HvNRT2.2, HvNRT2.3, and HvNRT2.4 transcripts, and washed at high stringency.