Chloroplast energization and oxidation of P700/plastocyanin in illuminated leaves at reduced levels of CO2 or oxygen
Chloroplast energization and oxidation of P700/plastocyanin in illuminated leaves at reduced levels of CO2 or oxygen
复制标题
在 CO2 或氧气水平降低的情况下，光照叶片中 P700/质体蓝素的叶绿体供能和氧化
DOI：
10.1007/bf00029817
复制
发表时间：
1992
影响因子：
3.7
通讯作者：
É. Katona
中科院分区：
文献类型：
--
作者：
U. Heber;S. Neimanis;K. Siebke;G. Schönknecht;É. Katona
测定了光照叶片的叶绿素荧光、光散射、电致变色位移P515和一些光合作用中间产物的水平。改变气相中的氧气和二氧化碳浓度，以获得在水分胁迫产生的条件下控制光系统II活性的信息，当气孔关闭限制二氧化碳进入光合作用装置时。光散射和依赖能量的荧光猝灭表明，在高强度光照下，即使在无CO_2的空气中或在含有35μ11~(-1)CO_2的1%氧气中，线性电子传递被抑制时，叶绿体仍有高水平的能量传递。基于磷酸甘油酸、二羟丙酮磷酸和二羟丙酮磷酸二钠测量的磷酸化潜力的计算表明，在含有35μL L-1CO2的空气中，类囊体内和类囊体外的质子浓度之比仅略高于无二氧化碳空气中或1%氧气/35μL L-1CO2中。厌氧条件阻碍了叶绿体明显的能量转化。电子流量的受体限制导致电子传递链的高还原水平，其特征是P700的氧化减少，不仅在厌氧条件下，而且在空气中，当没有CO2时，在1%氧气中，当CO2浓度降至35μ11-1时，P700的氧化减少。P700+在空气中的CO2补偿点或附近的光积累表明电子传递是有效的控制。提出了光呼吸和光合作用电子流、电子流向氧和循环电子流之间的相互作用。场指示电致变色位移(P515)在关光时被测量为快速吸收减少，这与光中P700+的光积累程度密切相关。
Chlorophyll fluorescence, light scattering, the electrochromic shift P515and levels of some photosynthetic intermediates were measured in illuminated leaves. Oxygen and CO2concentrations in the gas phase were varied in order to obtain information on control of Photosystem II activity under conditions such as produced by water stress, when stomatal closure restricts access of CO2to the photosynthetic apparatus. Light scattering and energy-dependent fluorescence quenching indicated a high level of chloroplast energization under high intensity illumination even when linear electron transport was curtailed in CO2-free air or in 1% oxygen with 35 μll-1CO2. Calculations of the phosphorylation potential based on measurements of phosphoglycerate, dihydroxyacetone phosphate and NADP revealed ratios of intrathylakoid to extrathylakoid proton concentrations, which were only somewhat higher in air containing 35 μl l-1CO2than in CO2-free air or 1% oxygen/35 μl l-1CO2. Anaerobic conditions prevented appreciable chloroplast energization. Acceptor-limitation of electron flow resulted in a high reduction level of the electron transport chain, which is characterized by decreased oxidation of P700, not only under anaerobic conditions, but also in air, when CO2was absent, and in 1% oxygen, when the CO2concentration was reduced to 35 μll-1. Efficient control of electron transport was indicated by the photoaccumulation of P700+at or close to the CO2compensation point in air. It is proposed to require the interplay between photorespiratory and photosynthetic electron flows, electron flow to oxygen and cyclic electron flow. The field-indicating electrochromic shift (P515) measured as a rapid absorption decrease on switching the light off followed closely the extent of photoaccumulation of P700+in the light.