Biologisches Institut II der Universität, Schänzlestrasse 1, D-7800, Freiburg, Federal Republic of Germany.
Planta. 1986 Sep;168(3):369-76. doi: 10.1007/BF00392362.
Nitrite reductase (NIR; EC 1.7.7.1) is a central enzyme in nitrate assimilation and is localized in plastids. The present study concerns the regulation of the appearance of NIR in cotyledons of the mustard (Sinapis alba L.) seedling. It was shown that light exerts its positive control over the nitrate-mediated induction of NIR via the farred-absorbing form of phytochrome. Without nitrate the light effect cannot express itself; even though the light signal is accumulated in the cotyledons it remains totally cryptic in the absence of nitrate. Moreover, it was recognised that 'intact plastids' are important in the control of the appearance of NIR. If the plastids are damaged by photooxidation the action of nitrate and phytochrome on NIR appearance is abolished. The appearance of nitrate reductase (NR; EC 1.6.6.1) responds similarly to photooxidative damage even though this enzyme is cytosolic. While the data strongly indicate that some 'plastidic signal' is a prerequisite for the nitrate-induced and phytochrome-modulated appearance of NIR and NR, the possibility could not be ruled out that photooxidative damage affects the accumulation of NIR in the organelle.
亚硝酸盐还原酶（NIR；EC 1.7.7.1）是硝酸盐同化过程中的一种重要酶，位于质体中。本研究关注的是芥菜（Sinapis alba L.）幼苗子叶中 NIR 出现的调控。结果表明，光通过远红光吸收型的光敏色素对硝酸盐介导的 NIR 诱导起正向调控作用。没有硝酸盐，光效应就无法表现出来；即使在子叶中积累了光信号，但在没有硝酸盐的情况下，它仍然完全处于隐蔽状态。此外，人们认识到“完整的质体”在控制 NIR 出现中很重要。如果质体被光氧化破坏，硝酸盐和光敏色素对 NIR 出现的作用就会被消除。硝酸盐还原酶（NR；EC 1.6.6.1）的出现对光氧化损伤的反应类似，尽管这种酶位于细胞质中。尽管这些数据强烈表明，某些“质体信号”是硝酸盐诱导和光敏色素调节 NIR 和 NR 出现的前提条件，但不能排除光氧化损伤会影响 NIR 在细胞器中的积累。
