Laboratoire du Métabolisme, Institut National de la Recherche Agronomique, Route de St-Cyr, 78026 Versailles Cedex, France.
Plant Physiol. 1992 Jul;99(3):979-86. doi: 10.1104/pp.99.3.979.
The quantum efficiencies of photosystems I and II (PSI and PSII), [NADP]/[NADPH] ratios, and the activities of chloroplastic fructose-1,6-bisphosphatase and NADP-malate dehydrogenase were measured in intact pea (Pisum sativum L.) leaves in air following the transition from darkness to 750 microeinsteins per square meter per second irradiance. PSII efficiency declined from a low value to a minimum within the first 10 to 15 seconds of irradiance, after which it increased progressively to the steady-state value. The resistance of electron flow between the photosystems was high at this time, but it was not the principal factor limiting electron flow. Oxidation of P700 was restricted by acceptor side processes for approximately the first 60 seconds of illumination. Once the acceptor side limitation was relieved, the oxidation state of P700 was used to estimate the quantum efficiency of electron transport by PSI. This was observed to increase progressively with time. The quantum efficiencies of both photosystems increased in parallel, consistent with a predominant role for noncyclic electron transport. Fructose-1,6-bisphosphatase activity increased in an approximately sigmoidal fashion with time of irradiance, paralleling the changes in the quantum efficiencies of the photosystems. In contrast, the activation of NADP-malate dehydrogenase did not show a lag period but increased with time, reaching a maximum value at about 50 seconds of illumination, after which it declined. The NADP pool was not extensively reduced during the first 10 seconds of illumination, but became so subsequently. It remained in the reduced state until about 60 seconds of illumination and then became relatively oxidized. The empirical relationship between NADP-malate dehydrogenase activity and the reduction state of the NADP pool supports the suggestion that NADP-malate dehydrogenase activity is a useful estimate of the reduction state of the stroma.
在从黑暗过渡到 750 微爱因斯坦/平方米/秒的辐照度后，测定了完整豌豆（Pisum sativum L.）叶片中光系统 I 和 II（PSI 和 PSII）的量子效率、[NADP]/[NADPH] 比值以及叶绿体果糖-1,6-二磷酸酶和 NADP-苹果酸脱氢酶的活性。在辐照的最初 10 到 15 秒内，PSII 效率从一个低值下降到最小值，之后逐渐增加到稳态值。此时，两个光系统之间的电子流阻力很高，但它不是限制电子流的主要因素。在光照的最初 60 秒左右，P700 的氧化受到受体侧过程的限制。一旦受体侧限制得到缓解，P700 的氧化态就被用来估计 PSI 电子传递的量子效率。观察到它随着时间的推移逐渐增加。两个光系统的量子效率平行增加，这与非循环电子传递的主要作用一致。果糖-1,6-二磷酸酶活性随着辐照时间呈近似 S 形增加，与光系统量子效率的变化平行。相比之下，NADP-苹果酸脱氢酶的激活没有滞后期，而是随着时间的增加而增加，在光照 50 秒左右达到最大值，之后下降。在光照的最初 10 秒内，NADP 池没有被广泛还原，但随后被还原。它一直处于还原状态，直到光照约 60 秒，然后相对氧化。NADP-苹果酸脱氢酶活性与 NADP 池还原状态之间的经验关系支持了 NADP-苹果酸脱氢酶活性是基质还原状态的有用估计的观点。
