NR was mainly responsible for the S(NO) accumulation in noe1. A to E, NOS (A) and NR (B) activities, relative expression levels of OsNIA1 (C) and OsNIA2 (D) by quantitative RT-PCR (with the wild-type value [WT] set as 1.0), and nitrate content (E) in wild-type and noe1 plants. FW, Fresh weight. F, Effects of tungstate (an NR inhibitor) and l-NMMA (an NOS inhibitor) on endogenous NO production in wild-type and noe1 plants. Both 10-d-old wild-type and noe1 seedlings cultivated under low light (400 μmol m−2 s−1) were treated with tungstate or l-NMMA under high light (1,600 μmol m−2 s−1) for 2 d. These data were obtained from three independent replicates. Tungstate100 and Tungstate200, 100 and 200 μm tungstate; l-NMMA200 and l-NMMA300, 200 and 300 μm l-NMMA; PTIO200, 200 μm PTIO. * P < 0.05, ** P < 0.01 (t test).