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首页> 外文期刊>Russian Journal of Plant Physiology >Activities of Noncyclic and Alternative Pathways of Photosynthetic Electron Transport in Leaves of Broad Bean Plants Grown at Various Light Irradiances
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Activities of Noncyclic and Alternative Pathways of Photosynthetic Electron Transport in Leaves of Broad Bean Plants Grown at Various Light Irradiances

机译：不同光辐射条件下蚕豆叶片光合电子传递的非循环和替代途径的活性

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摘要

Activities of noncyclic and alternative pathways of photosynthetic electron transport were studied in intact leaves of broad been (Viciafaba L.) seedlings grown under white light at irradiances of 176, 36, and 18 mu mol quanta/(m~2 s). Electron flowswere followed from light-induced absorbance changes at 830 nm related to redox transformations of P700, the photoactive PSI pigment. The largest absorbance changes at 830 nm, induced by either white or far-red light, were observed in leaves of seedlingsgrown at irradiance of 176 mu mol quanta/(m~2 s), which provides evidence for the highest concentration of PSI reaction centers per unit leaf area in these seedlings. When actinic white light of 1800 mu mol quanta/(m~2 s) was turned on, the P700 oxidation proceeded most rapidly in leaves of seedlings grown at irradiance of 176 mu mol quanta/(m~2 s). The rates of electron transfer from PSII to PSI were measured from the kinetics of dark P700~+ reduction after turning off white light. These rates were similar in leaves of all light treatments studied, and their characteristic reaction times were found to range from 9.2 to 9.5 ms. Four exponentially decaying components were resolved in the kinetics of dark P700~+ reduction after leaf exposure to far-red light. A minor but the fastest component of P700~+ reduction with a halftime of 30-60 ms was determined by electron transfer from PSII, while the three other slow components were related to the operation of alternative electron transport pathways. Their halftimes and relative magnitudes were almost independent on irradiance during plant cultivation. It is concluded that irradiance during plant growth affects the absolute content of PSI reaction centers in leaves but did not influence the rates of noncyclic and alternative electron transport.
机译：在176、36和18μmolQuanta /（m〜2 s）辐照下，研究了在白光下生长的阔叶（Viciafaba L.）幼苗完整叶片的光合电子传递的非循环途径和替代途径的活性。电子流是由光诱导的PSI颜料P700的氧化还原转变引起的，在830 nm处光诱导的吸光度变化引起的。在176μmol Quanta /（m〜2 s）的照度下生长的幼苗叶片中，观察到由白光或远红光引起的在830 nm处最大的吸光度变化，这为PSI反应中心的最高浓度提供了证据这些幼苗的每单位叶面积。当打开1800μmolQuanta /（m〜2 s）的光化白光时，P700氧化在以176μmolQuanta /（m〜2 s）照度生长的幼苗叶片中进行最快。通过关闭白光后暗P700〜+还原的动力学来测量从PSII到PSI的电子转移速率。这些速率在研究的所有光处理叶片中均相似，发现其特征性反应时间为9.2至9.5毫秒。叶片暴露于远红光后，深色P700〜+还原的动力学过程中解析出四个指数衰减的成分。通过PSII的电子转移确定了P700〜+还原过程中次要但最快的部分（半衰期为30-60 ms），而其他三个慢的部分与替代电子传输途径的运行有关。它们的半衰期和相对幅度几乎与植物栽培期间的辐照度无关。结论是植物生长过程中的辐照度会影响叶片中PSI反应中心的绝对含量，但不会影响非环状和交替电子传输的速率。

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