Ullrich-Eberius C I, Novacky A, Ball E
Institut für Botanik, Technische Hochschule Darmstadt, D-6100 Darmstadt, Federal Republic of Germany.
Plant Physiol. 1983 May;72(1):7-15. doi: 10.1104/pp.72.1.7.
The effect of CN(-) and N(2) on the electrical membrane potential (E(m)) was compared with that of CN(-) on the ATP levels in cotyledons of Gossypium hirsutum and in Lemna gibba L. In mature cotton tissue, CN(-) depolarized E(m) to the energy-independent diffusion potential (E(D)) in the dark. In the light E(m) recovered transiently. The same was observed in leaves of Nicotiana, Avena, Impatiens, Kalanchoë, and in Lemna. In contrast, in young cotton cotyledons and tobacco leaves and, to a large extent, in +sucrose-grown Lemna, E(m) was depolarized to E(D) also in the light in a similar way as in the dark.In Lemna grown without sucrose, the energy-dependent component of E(m) was only partially depolarized by CN(-) in dark or light. Cyanide plus salicylhydroxamic acid completely reduced E(m) to E(D), abolished respiration and photosynthesis, and severely diminished the ATP level. This suggests the operation of a CN(-)-insensitive respiration in uninjured Lemna. The initial CN(-)-induced decay of the ATP level in cotton and Lemna was more rapid than the decay of E(m). CN(-)-induced oscillations of the ATP level were followed by similar but slower oscillations of E(m). This supports the view of a general dependence of E(m) on ATP. Discrepancies between inhibitor-induced changes of E(m) and ATP levels are suggested to result from additional regulation of E(m) by the cytoplasmatic pH value.A comparison of E(D) in young and mature cotton cotyledons in the dark and in the light suggests that in growing young cotyledons the different effect of CN(-) in the light is due to a less effective photosynthesis together with high mitochondrial respiration. In Lemna and in mature cotton tissue, E(m) in the light is maintained by noncyclic photophosphorylation and photosystem II, which is only partly inhibited by CN(-), thus resulting in an incomplete depolarization and recovery of E(m). Complete inhibition of photosynthetic O(2) evolution and membrane depolarization by CN(-) plus salicylhydroxamic acid are suggested to result from photooxidation.
比较了氰离子（CN⁻）和氮气（N₂）对陆地棉子叶以及浮萍（Lemna gibba L.）中膜电位（Eₘ）的影响，以及氰离子对其ATP水平的影响。在成熟的棉花组织中，黑暗条件下氰离子将Eₘ去极化至与能量无关的扩散电位（Eᴅ）。光照下Eₘ会短暂恢复。烟草、燕麦、凤仙花、落地生根的叶片以及浮萍中也观察到同样的现象。相反，在幼嫩的棉花子叶和烟草叶片中，以及在很大程度上在添加蔗糖培养的浮萍中，光照下Eₘ也会像在黑暗中一样以类似方式去极化至Eᴅ。在不添加蔗糖培养的浮萍中，黑暗或光照条件下氰离子仅使Eₘ的能量依赖成分部分去极化。氰离子加水杨羟肟酸可使Eₘ完全降至Eᴅ，消除呼吸作用和光合作用，并严重降低ATP水平。这表明未受损的浮萍中存在对氰离子不敏感的呼吸作用。氰离子诱导的棉花和浮萍中ATP水平的初始下降比Eₘ的下降更快。氰离子诱导的ATP水平振荡之后是Eₘ类似但较慢的振荡。这支持了Eₘ普遍依赖ATP的观点。抑制剂诱导的Eₘ变化与ATP水平之间的差异被认为是由于细胞质pH值对Eₘ的额外调节所致。对黑暗和光照条件下幼嫩和成熟棉花子叶中Eᴅ的比较表明，在生长中的幼嫩子叶中，光照下氰离子的不同作用是由于光合作用效率较低以及线粒体呼吸作用较强。在浮萍和成熟的棉花组织中，光照下Eₘ由非循环光合磷酸化和光系统II维持，而氰离子仅对其产生部分抑制，从而导致Eₘ不完全去极化和恢复。氰离子加水杨羟肟酸对光合氧气释放的完全抑制和膜去极化被认为是由光氧化作用引起的。
