Department of Plant Biology, University of Hull, Hull HU6 7RX, England.
Plant Physiol. 1983 Jun;72(2):280-6. doi: 10.1104/pp.72.2.280.
Polarography, using cylindrical platinum electrodes, proved suitable for measuring changes in the internal apical O(2) concentration of the primary root of pea (Pisum sativum L. cv Meteor) effected by KCN and/or salicylhydroxamic acid (SHAM) in the bathing medium. An electrical rootaeration analog was used to help evaluate some of the results. Concentrations of KCN </=0.05 millimolar had no significant effect. In response to 0.1 millimolar KCN, the O(2) concentration rose substantially for approximately 2 hours, then declined, and after 10 hours had frequently fallen below the pretreatment level. Such changes suggest an initial inhibition of cytochrome oxidase-mediated O(2) uptake followed by an induction of the alternative, cyanide-resistant respiratory pathway. These treatments proved nonlethal. Changes in O(2) concentration similar to those described for 0.1 millimolar KCN were observed in response to 1 and 10 millimolar KCN but these treatments were lethal and the root apex became soft and often appeared flooded. Roots survived and showed no significant responses when treated with SHAM at concentrations </=5 millimolar. However, when the alternative pathway had been (apparently) induced by 0.1 millimolar KCN, the addition of 5 millimolar SHAM to the bathing medium caused a substantial and persistent rise in the root apical O(2) concentration, suggesting that this (nonlethal) concentration of SHAM could indeed inhibit O(2) uptake via the cyanide-resistant pathway.It is concluded that while O(2) uptake normally occurs by the cytochrome pathway in the primary pea root, the alternative, cyanide-resistant pathway can be induced by 0.1 millimolar KCN.
极谱法，使用圆柱形铂电极，被证明适合测量在沐浴介质中氰化钾（KCN）和/或水杨羟肟酸（SHAM）对豌豆（Pisum sativum L. cv Meteor）主根内部顶端 O(2)浓度变化的影响。使用电根旋转模拟来帮助评估部分结果。浓度 <= 0.05 毫摩尔的 KCN 没有显著影响。对于 0.1 毫摩尔的 KCN，O(2)浓度在大约 2 小时内显著上升，然后下降，10 小时后经常低于预处理水平。这些变化表明最初抑制细胞色素氧化酶介导的 O(2)摄取，随后诱导替代的、氰化物抗性呼吸途径。这些处理被证明是非致命的。类似于 0.1 毫摩尔 KCN 描述的 O(2)浓度变化，在响应 1 和 10 毫摩尔 KCN 时也观察到，但这些处理是致命的，根尖端变得柔软，经常看起来被淹没。当用浓度 <= 5 毫摩尔的 SHAM 处理时，根存活且没有显示出明显的反应。然而，当替代途径（显然）由 0.1 毫摩尔 KCN 诱导时，将 5 毫摩尔 SHAM 添加到沐浴介质中会导致根尖 O(2)浓度显著且持续上升，表明这种（非致命）浓度的 SHAM 确实可以抑制通过氰化物抗性途径的 O(2)摄取。结论是，虽然 O(2)摄取通常通过豌豆主根中的细胞色素途径发生，但替代的、氰化物抗性途径可以由 0.1 毫摩尔 KCN 诱导。
