Effect of K deficiency on the transcriptional expression of OsHAK5 in rice. Ten-day-old rice seedlings (cv Nipponbare) were grown in IRRI solution for 2 weeks and then transferred to K-sufficient (1 mm  K; +K) and K-deficient (0 mm  K; −K) solutions for the indicated durations. Total RNAs were isolated from roots, basal node and sheath, and leaf blades of the seedlings, and OsHAK5 transcript levels were determined by qRT-PCR. A housekeeping gene, ACTIN (OsRac1; accession no. AB047313), was used as an internal standard. Error bars indicate se of three biological replicates (n = 3). All the primers are listed in Supplemental Table S2.