Yandow T S, Klein R M
Botany Department, University of Vermont, Burlington, Vermont 05405.
Plant Physiol. 1986 Jul;81(3):723-5. doi: 10.1104/pp.81.3.723.
Nitrate reductase activity (NRA) was found in primary roots, but not in foliage of red spruce (Picea rubens Sarg.) seedlings. Nitrate induced NRA:NH(4) (+) did not induce and slightly depressed NRA in older seedlings. Induction required 8 hours and, once induced, NRA decreased slowly in the absence of exogenous NO(3) (-). Seedlings were grown in perlite with a complete nutrient solution containing NH(4) (+) to limit NR induction. Established seedlings were stressed with nutrient solutions at pH 3, 4, or 5 supplemented with Cl(-) salts of Al, Cd, Pb, or Zn each at two concentrations. NRA in primary root tips was measured at 2, 14, 28, and 42 days. NRA induction was greatest at pH 3, and remained high during the period of study. NRA induction at pH 4 was lower. Metal ions suppressed NRA at pH 3 and 5, but enhanced NRA at pH 4. It is concluded that acidity and soluble metals in the root environment of red spruce are unlikely to be important factors in nitrogen transformations in red spruce roots.
在红云杉（Picea rubens Sarg.）幼苗的初生根中发现了硝酸还原酶活性（NRA），但在其叶片中未发现。硝酸盐可诱导NRA：NH(4) (+) 不会诱导且会略微降低老龄幼苗中的NRA。诱导需要8小时，一旦诱导，在没有外源NO(3) (-) 的情况下NRA会缓慢下降。幼苗种植在珍珠岩中，使用含有NH(4) (+) 的完全营养液以限制NR诱导。用pH值为3、4或5的营养液对成年幼苗进行胁迫处理，每种营养液添加两种浓度的Al、Cd、Pb或Zn的Cl(-) 盐。在第2、14、28和42天测量初生根尖中的NRA。在pH值为3时NRA诱导作用最大，并且在研究期间保持较高水平。在pH值为4时NRA诱导作用较低。金属离子在pH值为3和5时抑制NRA，但在pH值为4时增强NRA。得出的结论是，红云杉根系环境中的酸度和可溶性金属不太可能是红云杉根系氮转化的重要因素。
