EFFECT OF TEMPERATURE ON THE CO2/O2 SPECIFICITY OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE OXYGENASE AND THE RATE OF RESPIRATION IN THE LIGHT - ESTIMATES FROM GAS-EXCHANGE MEASUREMENTS ON SPINACH
EFFECT OF TEMPERATURE ON THE CO2/O2 SPECIFICITY OF RIBULOSE-1,5-BISPHOSPHATE CARBOXYLASE OXYGENASE AND THE RATE OF RESPIRATION IN THE LIGHT - ESTIMATES FROM GAS-EXCHANGE MEASUREMENTS ON SPINACH
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DOI：
10.1007/bf00392238
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发表时间：
1985-01-01
期刊：
影响因子：
4.3
通讯作者：
FARQUHAR, GD
中科院分区：
文献类型：
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作者：
BROOKS, A;FARQUHAR, GD
在不同辐照度下，测量完整菠菜 (Spinacia oleracea L.) 叶子上的净 CO2 同化速率 (A) 对 CO2 细胞间分压 (pi) 的响应。对这些反应进行分析，找出光合作用 CO2 吸收速率等于光呼吸 CO2 释放速率时的 pi 值。在此 CO2 分压（表示为.**GRAPHIC**.CO2 同化净速率为负值，表明在光照下存在非光呼吸 CO2 演化。因此.**GRAPHIC**.低于 CO2 补偿点.GAMMA..在叶温从 15 到 30°C 时获得了.**GRAPHIC**.的估计值，并且 CO2/O2 特异性为 根据这些数据计算核酮糖 1,5-二磷酸 (RuBP) 羧化酶/加氧酶 (E.C. 4.1.1.39)，同时考虑 CO2 和 O2 溶解度随温度的变化。 CO2/O2 特异性随着温度的升高而降低。因此，我们得出结论，温度对光呼吸与光合作用比率的影响不仅仅是温度对 CO2 溶解度的不同影响的结果 和氧气。我们对 RuBP 羧化酶/加氧酶的 CO/O2 特异性的估计与其他作者的体外测量结果进行了比较。光照下非光呼吸 CO2 释放速率 (Rd) 是从 A 值获得的。**图形**。在如此低的 CO2 分压下，Rd 始终小于黑暗中 CO2 的速率，并且似乎随着辐照度的增加而减小。的 下降在约 100μmol 量子 m-2 s-1 时最显着，在较高辐照度下下降不太明显。然而，在某一特定辐照度下，不同叶片中 Rd 占黑暗中 CO2 释放速率的比例相似，并且该比例不受叶片温度或 [O2]（环境及更高温度）的影响。在高 [CO2] 和高辐照度条件下持续数小时后，黑暗中 CO2 释放速率增加，Rd 增加 也增加了。
Responses of the rate of net CO2 assimilation (A) to the intercellular partial pressure of CO2 (pi) were measured on intact spinach (Spinacia oleracea L.) leaves at different irradiances. These responses were analysed to find the value of pi at which the rate of photosynthetic CO2 uptake equalled that of photorespiratory CO2 evolution. At this CO2 partial pressure (denoted .**GRAPHIC**. net rate of CO2 assimilation was negative, indicating that there was non-photorespiratory CO2 evolution in the light. Hence .**GRAPHIC**. was lower than the CO2 compensation point, .GAMMA.. Estimates of .**GRAPHIC**. were obtained at leaf temperatures from 15 to 30.degree. C, and the CO2/O2 specificity of ribulose 1,5-bisphosphate (RuBP) carboxylase/oxygenase (E.C. 4.1.1.39) was calculated from these data, taking into account changes in CO2 and O2 solubilities with temperature. The CO2/O2 specificity decreased with increasing temperature. Therefore we concluded that temperature effects on the ratio of photorespiration to photosynthesis were not solely the consequence of differential effects of temperature on the solubilities of CO2 and O2. Our estimates of the CO/O2 specificity of RuBP carboxylase/oxygenase are compared with in-vitro measurements by other authors. The rate of non-photorespiratory CO2 evolution in the light (Rd) was obtained from the value of A at .**GRAPHIC**. At this low CO2 partial pressure, Rd was always less than the rate of CO2 in darkness and appeared to decrease with increasing irradiance. The decline was most marked up to about 100 .mu.mol quanta m-2 s-1 and less marked at higher irradiances. At one particular irradiance, however, Rd as a proportion of the rate of CO2 evolution in darkness was similar in different leaves and this proportion was unaffected by leaf temperature or by [O2] (ambient and greater). After conditions of high [CO2] and high irradiance for several hours, the rate of CO2 evolution in darkness increased and Rd also increased.