Nitric oxide (NO) being a signaling molecule inside the plant cells, play significant role in signaling cascades and protection against environmental stresses. However, the protective role of NO in alleviating As toxicity in rice plants is currently not available. In the present study, the level of NO, nitrogen (N), inorganic N (nitrate, ammonium), thiols {TT (Total thiols), NPT (Nonprotein thiol)} and AAs contents along with N assimilating enzymes (NR, GDH, GOGAT) were analyzed after exposure of As^III/NO treatment alone, and in combination. NO supplementation enhanced the content of N, inorganic N & thiol contents, NR, GOGAT activities, when compared with As^III exposure alone. In As^III exposed rice seedlings, content of AAs (except His, Arg, Met) reduced over the control, while supplementation of SNP improved AAs contents, compared to As^III treatment alone. In conclusion, rice seedlings supplemented with NO tolerate the As^III toxicity by reducing the N related parameters, thiol contents, altering the AA profile and enhanced the nutritional quality by increasing EAAs (essential amino acids) and NEAAs (non-essential amino acids).

一氧化氮（NO）是植物细胞内的信号分子，在信号级联反应和防止环境胁迫方面起着重要作用。然而，目前尚无NO在减轻水稻植物As毒性方面的保护作用。在本研究中，NO，氮（N），无机氮（硝酸盐，铵），硫醇{TT（总硫醇），NPT（非蛋白硫醇）}和AAs的含量以及N同化酶（NR，GDH，单独或联合使用As ^III / NO处理后，进行GOGAT分析。与单独暴露于As ^III相比，添加NO可以提高N含量，无机N和硫醇含量，NR，GOGAT活性。在As ^III与单独的As ^III处理相比，在暴露的水稻幼苗中，AA的含量（His，Arg，Met除外）比对照降低，而补充SNP可以提高AA含量。总之，补充NO的水稻幼苗通过降低N相关参数，硫醇含量，改变AA谱并通过增加EAA（必需氨基酸）和NEAA（非必需氨基酸）来增强As ^III的毒性。