Activities of nitrate reductase and glutamine synthetase in rice seedlings during cyanide metabolism.
A study was conducted to investigate activities of nitrate reductase (NR) and glutamine synthetase (GS) in plants during cyanide metabolism. Young rice seedlings (Oryza sativa L. cv. XZX 45) were grown in the nutrient solutions containing KNO(3) or NH(4)Cl and treated with free cyanide (KCN). Cyanide in solutions and in plant materials was analyzed to estimate the phyto-assimilation potential. Activities of NR and GS in different parts of rice seedlings were assayed in vivo. Seedlings grown on NH(4)(+) showed significantly higher relative growth rate than those on NO(3)(-) (p<0.05) in the presence of exogenous cyanide. The metabolic rates of cyanide by seedlings were all positively correlated to the concentrations supplied. A negligible difference was observed between the two treatments with nitrate and ammonium (p>0.05). Enzymatic assays showed that cyanide (≥0.97mg CN L(-1)) impaired NR activity significantly in both roots and shoots (p<0.05). The effect of cyanide on GS activity in roots was more evident at 1.93mg CN L(-1), suggesting that NR activity was more susceptible to change from cyanide application than GS activity. The results observed here suggest that the exogenous cyanide, which to a certain level has a beneficial role in plant nutrition.
Department of Environmental Sciences & Engineering, Hunan Agricultural University, Changsha, 41028, People's Republic of China. yuxiaozhang@hotmail.com
Xiao-Zhang
XZ
Yu
Fu-Zhong
FZ
Zhang
D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050901:Nitrate Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009566:Nitrates / Q000494:pharmacology; D012275:Oryza / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D011190:Potassium Cyanide / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
D004791:Enzyme Inhibitors; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase; D011190:Potassium Cyanide