Effect of Nitrate on Activities and Transcript Levels of Nitrate Reductase and Glutamine Synthetase in Rice

摘要

Real-time polymerase chain reaction analysis was used to compare the effect of NO-3on the activities of nitrate reductase(NR)and glutamine synthetase(GS),and the transcript levels of two NR genes,OsNia1 and OsNia2,two cytosolic GS1 genes,OsGln1;1 and OsGln1;2,and one plastid GS2 gene OsGln2,in two rice(Oryza sativa L.)cultivars Nanguang(NG)and Yunjing(YJ).Both cultivars achieved greater biomass and higher total N concentration when grown in a mixed N supply than in sole NH+ 4nutrition.Supply of NO -3increased NR activity in both leaves and roots.Expression of both NR genes was also substantially enhanced and transcript levels of OsNia2 were significantly higher than those of OsNia1.NO-3also caused an increase in GS activity,but had a complex effect on the expression of the three GS genes.In roots,the OsGln1;1 transcript increased,but OsGln1;2 decreased.In leaves,NO-3had no effect on the GS1 expression,but the transcript for OsGln2 increased both in the leaves and roots of rice with a mixed supply of N.These results suggested that the increase in GS activity might be a result of the complicated regulation of the various GS genes. In addition,the NO-3 induced increase of biomass,NR activity,GS activity,and the transcript levels of NR and GS genes were proportionally higher in NG than in YJ,indicating a stronger response of NG to NO-3nutrition than YJ.