The water-water cycle in leaves is not a major alternative electron sink for dissipation of excess excitation energy when CO2 assimilation is restricted
The water-water cycle in leaves is not a major alternative electron sink for dissipation of excess excitation energy when CO2 assimilation is restricted
复制标题
DOI：
10.1111/j.1365-3040.2011.02288.x
复制
发表时间：
2011-05-01
影响因子：
7.3
通讯作者：
Baker, Neil R.
中科院分区：
文献类型：
--
作者：
Driever, Steven M.;Baker, Neil R.
电子通量从水通过光系统II（PSII）和PSI到氧气（水-水循环）可能提供了一种机制，当CO2同化受到限制时，多余的激发能在叶片中消散。利用质谱法测定了菜豆和玉米叶片在光合作用饱和CO2浓度和CO2补偿点时的O-2吸收和演化以及CO2吸收。在高CO2和低O-2浓度下，菜豆没有观察到显着的水-水循环活动。在CO2补偿点和3%O-2的水-水循环活动率低，占30%的线性电子通量从水。在玉米叶片中，在补偿点检测到可忽略的水-水循环活性。在玉米光合作用诱导过程中，线性电子通量显著大于CO2同化，但没有检测到显著的水-水循环活动。芒草x在寒冷的温度下生长也表现出线性电子传递率大大超过CO2同化，但是，没有显着的水-水循环活动进行检测。显然，在某些条件下，水-水循环可以在叶中运行，但当CO2同化受到限制时，它并不作为多余激发能量的主要汇。
Electron flux from water via photosystem II (PSII) and PSI to oxygen (water-water cycle) may provide a mechanism for dissipation of excess excitation energy in leaves when CO2 assimilation is restricted. Mass spectrometry was used to measure O-2 uptake and evolution together with CO2 uptake in leaves of French bean and maize at CO2 concentrations saturating for photosynthesis and the CO2 compensation point. In French bean at high CO2 and low O-2 concentrations no significant water-water cycle activity was observed. At the CO2 compensation point and 3% O-2 a low rate of water-water cycle activity was observed, which accounted for 30% of the linear electron flux from water. In maize leaves negligible water-water cycle activity was detected at the compensation point. During induction of photosynthesis in maize linear electron flux was considerably greater than CO2 assimilation, but no significant water-water cycle activity was detected. Miscanthus x giganteus grown at chilling temperature also exhibited rates of linear electron transport considerably in excess of CO2 assimilation; however, no significant water-water cycle activity was detected. Clearly the water-water cycle can operate in leaves under some conditions, but it does not act as a major sink for excess excitation energy when CO2 assimilation is restricted.