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CO_2 assimilation-governing mechanisms based on the balance in chemical energy produced and consumed in the photosynthetic process.

基于光合作用过程中产生和消耗的化学能平衡的CO_2同化控制机制。

基本信息

批准号：
07456151
负责人：
KUBOTA Fumitake
金额：
$ 0.83万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

This study was conducted to understand the CO_2 assimilation-governing mechanism by relating the leaf CER (CO_2 exchange rate) with the chemical energy production-consumption balance between photosystem and CO_2 assimilation. (1) CER of mungbean leaves were determined as a time course under the intermittent illumination with 20 second-intervals of light on/off in the different combinations of CO_2 and O_2 concentrations and light intensities. Based on the calculation of the energy produced at the light-on (20s) moments and the weight of CO_2 assimilated at the light-off (20s) moments, the effect of the intermittent illumination on the Rubisco (RuBP Carboxylase/Oxygenase) activity was estimated. CER or light utilization efficiency was increased at the intermittent illumination in high light intensities, because CO_2 was possible to be assimilated at the light-off moments by using the accumulated energy at the light-on moments. Light activation level of Rubisco varied with CO_2 and O_2 concentrations. The relative activity between carboxylase and oxygenase differed depending on the environmental conditions, affecting the CER and light utilization efficiency at the intermittent illumination. (2) Then, to get more clear explain for the action balance between photosystem and CO_2 assimilation system, the relationships between CER and chlorophyll fluorescence quenching were studied. The improved measurement tools were skillfully assembled to make a simultaneous determination of both factors. It was evident in mungbean leaves that the energy consumption by photorespiration significantly affected, in relation to environmental factors, both CER and the potimal energy utilization efficiency in photosynthesis.

本研究将叶片CO_2交换率（CER）与光合系统和CO_2同化之间的化学能生产-消耗平衡联系起来，探讨CO_2同化的调控机制。(1)在不同CO_2和O_2浓度和光强组合下，以20秒的间歇光照为间隔，测定绿豆叶片的CER随时间的变化。通过计算光照（20 s）时产生的能量和光照（20 s）时同化的CO_2量，估算了间歇光照对Rubisco（RuBP羧化酶/加氧酶）活性的影响。在高光强间歇光照下，由于CO_2可以在熄灯时刻被利用，从而提高了光利用效率。Rubisco的光活化水平随CO_2和O_2浓度的变化而变化。羧化酶和加氧酶之间的相对活性因环境条件而异，影响间歇光照下的CER和光能利用效率。(2)为了更好地解释光合系统与CO_2同化系统之间的作用平衡，本文还研究了CER与叶绿素荧光猝灭之间的关系。改进后的测量工具被巧妙地组装起来，以同时确定这两个因素。绿豆叶片的光呼吸能量消耗与环境因子密切相关，对CER和光合作用的最大能量利用效率均有显著影响。