Siddiqi M Y, King B J, Glass A D
Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
Plant Physiol. 1992 Oct;100(2):644-50. doi: 10.1104/pp.100.2.644.
Effects of NO(2) (-), ClO(3) (-), and ClO(2) (-) on the induction of nitrate transport and nitrate reductase activity (NRA) as well as their effects on NO(3) (-) influx into roots of intact barley (Hordeum vulgare cv Klondike) seedlings were investigated. A 24-h pretreatment with 0.1 mol m(-3) NO(2) (-) fully induced NO(3) (-) transport but failed to induce NRA. Similar pretreatments with ClO(3) (-) and ClO(2) (-) induced neither NO(3) (-) transport nor NRA. Net ClO(3) (-) uptake was induced by NO(3) (-) but not by ClO(3) (-) itself, indicating that NO(3) (-) and ClO(3) (-) transport occur via the NO(3) (-) carrier. At the uptake step, NO(2) (-) and ClO(2) (-) strongly inhibited NO(3) (-) influx; the former exhibited classical competitive kinetics, whereas the latter exhibited complex mixed-type kinetics. ClO(3) (-) proved to be a weak inhibitor of NO(3) (-) influx (K(i) = 16 mol m(-3)) in a noncompetitive manner. The implications of these findings are discussed in the context of the suitability of these NO(3) (-) analogs as screening agents for the isolation of mutants defective in NO(3) (-) transport.
研究了亚硝酸根（NO₂⁻）、氯酸根（ClO₃⁻）和二氧化氯根（ClO₂⁻）对完整大麦（Hordeum vulgare cv Klondike）幼苗硝酸盐转运诱导及硝酸还原酶活性（NRA）的影响，以及它们对硝酸根（NO₃⁻）流入根部的影响。用0.1 mol m⁻³的NO₂⁻进行24小时预处理可完全诱导NO₃⁻转运，但未能诱导NRA。用ClO₃⁻和ClO₂⁻进行类似预处理既未诱导NO₃⁻转运也未诱导NRA。NO₃⁻可诱导ClO₃⁻的净吸收，而ClO₃⁻本身不能，这表明NO₃⁻和ClO₃⁻的转运是通过NO₃⁻载体进行的。在吸收步骤中，NO₂⁻和ClO₂⁻强烈抑制NO₃⁻流入；前者表现出典型的竞争动力学，而后者表现出复杂的混合型动力学。ClO₃⁻被证明是以非竞争性方式对NO₃⁻流入起弱抑制剂作用（Kᵢ = 16 mol m⁻³）。在这些NO₃⁻类似物作为筛选缺陷型NO₃⁻转运突变体的筛选剂的适用性背景下，讨论了这些发现的意义。
