Figure 1. Effect of N deprivation and nitrate resupply on the expression of five ANR1 related genes in rice roots.

Ten-day old rice seedlings grown in complete nutrient solutions were transferred to modified nutrient solutions during which 2.88 mM KNO₃ was the sole nitrogen source for 4 days. Transcript abundance was assayed by qPCR and was expressed relative to the abundance in roots of plants of the same age grown under continuous N (CK). The OsNAR2.1 gene, a known nitrate-regulated gene, was included for comparison. Treatments: CK: continuous KNO₃; −N4h: starved of N for 3 d and resupplied with KCl for 4 h; +N4h: resupplied with KNO₃ for 4 h; −N6h: starved of N for 3 d and resupplied with KCl for 6 h; +N6h: resupplied with KNO₃ for 6 h. The mRNA of OsActin was used as the reference. A Student’s t-test was calculated at the probability of either 5% (*, p<0.05) or (**, P<0.01).