Mawson B T, Zeiger E
Department of Biological Sciences, Stanford University, Stanford, California 94305.
Plant Physiol. 1991 Jul;96(3):753-60. doi: 10.1104/pp.96.3.753.
Chlorophyll a fluorescence transients from mesophyll and single guard cell pairs of Vicia faba were measured by microspectrofluorometry. In both chloroplast types, fluorescence induction (O to P) was similar under actinic blue and green light. In slow transients from mesophyll cell chloroplasts, blue and green light induced identical, typical rapid quenching from P to S, and the M peak. In contrast, the P to S transient from guard cell (GC) chloroplasts irradiated with blue light showed a much slower quenching rate, and the P to T transition showed no M peak. Actinic green light induced mesophyll-like transients in GC chloroplasts, including rapid quenching from P to S and the M peak. Detection of these transients in single pairs of GC and isolated protoplasts ruled out mesophyll contamination as a signal source. Green light induced a rapid quenching and the M peak in GC chloroplasts from several species. The effect of CO(2) concentration on the fluorescence transients was investigated in the presence of HCO(3) (-) at pH 6.8 and 10.0. In transients induced by green light in both chloroplast types, a pH increase concomitant with a reduction in CO(2) concentration caused an increase in the initial rate of quenching and the elimination of the M peak. Actinic blue light induced mesophyll-like transients from GC chloroplasts in the presence of 10 micromolar KCN, a concentration at which the blue light-induced stomatal opening is inhibited. Addition of 100 to 200 micromolar phosphate also caused large increases in fluorescence quenching rates and a M peak. These results indicate that blue light modulates photosynthetic activity in GC chloroplasts. This blue light effect is not observed in the absence of transduction events connected with the blue light response and in the presence of high phosphate concentrations.
通过显微分光荧光测定法测量了蚕豆叶肉细胞和单个保卫细胞对的叶绿素a荧光瞬变。在这两种叶绿体类型中，在光化蓝光和绿光下，荧光诱导（O到P）相似。在叶肉细胞叶绿体的慢速瞬变中，蓝光和绿光诱导了从P到S以及M峰的相同的典型快速猝灭。相比之下，用蓝光照射的保卫细胞（GC）叶绿体从P到S的瞬变显示出慢得多的猝灭速率，并且从P到T的转变没有M峰。光化绿光在GC叶绿体中诱导出类似叶肉细胞的瞬变，包括从P到S的快速猝灭和M峰。在单个GC对和分离的原生质体中检测到这些瞬变，排除了叶肉污染作为信号源的可能性。绿光在几种物种的GC叶绿体中诱导了快速猝灭和M峰。在pH 6.8和10.0存在HCO₃⁻的情况下，研究了CO₂浓度对荧光瞬变的影响。在两种叶绿体类型中由绿光诱导的瞬变中，pH升高伴随着CO₂浓度降低导致猝灭初始速率增加以及M峰消失。在存在10微摩尔KCN（一种抑制蓝光诱导气孔开放的浓度）的情况下，光化蓝光在GC叶绿体中诱导出类似叶肉细胞的瞬变。添加100至200微摩尔磷酸盐也导致荧光猝灭速率大幅增加以及出现M峰。这些结果表明蓝光调节GC叶绿体中的光合活性。在没有与蓝光反应相关的转导事件以及存在高磷酸盐浓度的情况下，未观察到这种蓝光效应。
