Figure 4. Effect of N-deprivation and re-supply on expression of OsNRT2.1, OsNAR2.1, OsIPS1 and OsSULTR1;1 in rice roots.

Rice seedlings were grown hydroponically in a growth cabinet. Nitrogen treatments were as described in Fig. 1. 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. Total RNA was extracted from roots and qPCR reactions were performed in triplicate for each RNA sample. 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).