RELATIONSHIPS AMONG ISOPRENE EMISSION RATE, PHOTOSYNTHESIS, AND ISOPRENE SYNTHASE ACTIVITY AS INFLUENCED BY TEMPERATURE
RELATIONSHIPS AMONG ISOPRENE EMISSION RATE, PHOTOSYNTHESIS, AND ISOPRENE SYNTHASE ACTIVITY AS INFLUENCED BY TEMPERATURE
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DOI：
10.1104/pp.98.3.1175
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发表时间：
1992-03-01
期刊：
影响因子：
7.4
通讯作者：
FALL, R
中科院分区：
文献类型：
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作者：
MONSON, RK;JAEGER, CH;FALL, R
绒豆（Mucuna pruriens L. var utilis）植物叶片异戊二烯的释放表现出依赖于植物生长温度的温度响应模式。生长在温暖条件下（34/28℃，昼/夜）的植物表现出45℃的最佳排放温度，而生长在较冷条件下（26/20℃，昼/夜）的植物表现出40℃的最佳排放温度。以前的一些研究已经提供了异戊二烯排放与光合作用之间联系的证据，最近的研究表明，异戊二烯排放与植物叶片中异戊二烯合成酶的活性有关。为了在异戊二烯排放的温度依赖性背景下进一步探索这种联系，我们确定了光合电子传递、CO2同化和异戊二烯合成酶活性的相对温度依赖性。当在较宽的温度范围内测量时，异戊二烯发射率的温度依赖性与电子传递速率或CO2同化速率都不密切相关。电子传递速率和CO2同化速率的最佳温度比异戊二烯发射速率的最佳温度低5 ~ 10℃。异戊二烯辐射对光子通量密度的依赖性也受测量温度的影响，其模式与电子传输速率和CO2同化速率的模式无关。因此，在26℃和34℃下，尽管电子传递速率和CO2同化速率没有变化，异戊二烯发射速率却发生了显著变化。当温度从26℃升高到34℃时，异戊二烯排放物的量子产率受到刺激，而CO2同化的量子产率则受到抑制。在温室生长的白杨（Populus tremuloides Michaux.）叶片中，抑制异戊二烯排放的高温阈值与高温诱导的异戊二烯合成酶体外活性降低密切相关。综上所述，结果表明，尽管异戊二烯排放速率与光合作用之间可能存在联系，但异戊二烯排放的温度依赖性并非仅由CO2同化速率或电子传输速率决定。相反，我们认为调节主要是通过异戊二烯合成酶完成的。
Isoprene emissions from the leaves of velvet bean (Mucuna pruriens L. var utilis) plants exhibited temperature response patterns that were dependent on the plant's growth temperature. Plants grown in a warm regimen (34/28-degrees-C, day/night) exhibited a temperature optimum for emissions of 45-degrees-C, whereas those grown in a cooler regimen (26/20-degrees-C, day/night) exhibited an optimum of 40-degrees-C. Several previous studies have provided evidence of a linkage between isoprene emissions and photosynthesis, and more recent studies have demonstrated that isoprene emissions are linked to the activity of isoprene synthase in plant leaves. To further explore this linkage within the context of the temperature dependence of isoprene emissions, we determined the relative temperature dependencies of photosynthetic electron transport, CO2 assimilation, and isoprene synthase activity. When measured over a broad range of temperatures, the temperature dependence of isoprene emission rate was not closely correlated with either the electron transport rate or the CO2 assimilation rate. The temperature optima for electron transport rate and CO2 assimilation rate were 5 to 10-degrees-C lower than that for the isoprene emission rate. The dependence of isoprene emissions on photon flux density was also affected by measurement temperature in a pattern independent of those exhibited for electron transport rate and CO2 assimilation rate. Thus, despite no change in the electron transport rate or CO2 assimilation rate at 26 and 34-degrees-C, the isoprene emission rate changed markedly. The quantum yield of isoprene emissions was stimulated by a temperature increase from 26 to 34-degrees-C, whereas the quantum yield for CO2 assimilation was inhibited. In greenhouse-grown aspen leaves (Populus tremuloides Michaux.), the high temperature threshold for inhibition of isoprene emissions was closely correlated with the high temperature-induced decrease in the in vitro activity of isoprene synthase. When taken together, the results indicate that although there may be a linkage between isoprene emission rate and photosynthesis, the temperature dependence of isoprene emission is not determined solely by the rates of CO2 assimilation or electron transport. Rather, we propose that regulation is accomplished primarily through the enzyme isoprene synthase.