The Involvement of Dual Mechanisms of Photoinactivation of Photosystem II in Capsicum annuum L. Plants
The Involvement of Dual Mechanisms of Photoinactivation of Photosystem II in Capsicum annuum L. Plants
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DOI：
10.1093/pcp/pcp123
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发表时间：
2009-10-01
影响因子：
4.9
通讯作者：
Chow, Wah Soon
中科院分区：
文献类型：
--
作者：
Oguchi, Riichi;Terashima, Ichiro;Chow, Wah Soon
对于植物来说，光是不可或缺的资源。然而，它也会导致与光系统II(PSII)的光失活相关的光合作用活性的丧失。在对这种光灭活机制的研究中，目前有两种相互矛盾的假说。其一是叶片接收到的多余能量既没有被光合作用利用，也没有在非光化学猝灭中安全地消散，导致了光灭活。另一种是两步机制，其中由光子激发的锰是主要原因。在前一种假说中，PSII的光失活不应该发生在提供少量过剩能量的弱光中，但在后一种假说中，它应该发生。因此，我们在不同的辐照度下对这两种假设进行了检验。我们使用了一种系统，可以测量在自然条件下和在较长时间内完整叶片中功能PSII复合体的比例，这些叶片附着在经林可霉素处理的植物上，通过根吸收。叶片在弱、中、强光(30、60或950molm(2)S(1))下用白、蓝、绿或红色发光二极管阵列进行光灭活。我们的结果表明，每光子曝光的光灭活程度在强光下比在弱光下更高，这与过剩能量的丰度一致。然而，光灭活确实发生在弱光和少量过剩能量，蓝光引起的光灭活程度最大，其次是白光，绿光和红光，这一顺序可以从锰的吸收光谱中预测出来。这些结果表明，这两种机制都发生在光灭活过程中。
For plants, light is an indispensable resource. However, it also causes a loss of photosynthetic activity associated with photoinactivation of photosystem II (PSII). In studies of the mechanism of this photoinactivation, there are two conflicting hypotheses at present. One is that excess energy received by leaves, being neither utilized by photosynthesis nor dissipated safely in non-photochemical quenching, causes the photoinactivation. The other involves a two-step mechanism in which excitation of Mn by photons is the primary cause. In the former hypothesis, photoinactivation of PSII should not occur in low light that provides little excess energy, but in the latter hypothesis it should. Therefore, we tested these two hypotheses in different irradiances. We used a system that can measure the fraction of functional PSII complexes under natural conditions and over a long period in intact leaves, which were attached to a plant treated with lincomycin taken up via the roots. The leaves were photoinactivated in low, medium or high light (30, 60 or 950molm(2)s(1)) with white, blue, green or red light-emitting diode arrays. Our results showed that the extent of photoinactivation per photon exposure was higher in high light than in low light, consistent with the abundance of excess energy. However, photoinactivation did occur in low light with little excess energy, and blue light caused the greatest extent of photoinactivation followed by white, green and red light in this order, an order that can be predicted from the Mn absorbance spectrum. These results suggest that both mechanisms occur in the photoinactivation process.