Division of Integrated Life Sciences, Graduate School of Biostudies, Kyoto University, Kyoto 606-8502, Japan.
Plant Cell Physiol. 2011 Oct;52(10):1822-31. doi: 10.1093/pcp/pcr119. Epub 2011 Aug 26.
The thermal dissipation (TD) of absorbed light energy in PSII is considered to be an important photoprotection process in photosynthesis. A major portion of TD has been visualized through the analysis of Chl fluorescence as energy quenching (qE) which depends on the presence of the PsbS subunit. Although the physiological importance of qE-associated TD (qE-TD) has been widely accepted, it is not yet clear how much of the absorbed light energy is dissipated through a qE-associated mechanism. In this study, the fates of absorbed light energy in PSII with regard to different TD processes, including qE-TD, were quantitatively estimated by the typical energy allocation models using transgenic rice in which psbS genes were silenced by RNA interference (RNAi). The silencing of psbS genes resulted in a decrease in the light-inducible portion of TD, whereas the allocation of energy to electron transport did not change over a wide range of light intensities. The allocation models indicate that the energy allocated to qE-TD under saturating light is 30-50%. We also showed that a large portion of absorbed light energy is thermally dissipated in manners that are independent of qE. The nature of such dissipations is discussed.
在光合作用中，光吸收能量的热耗散（TD）被认为是一种重要的光保护过程。通过对叶绿素荧光的分析，已经观察到大部分 TD 表现为能量猝灭（qE），这取决于 PsbS 亚基的存在。尽管 qE 相关 TD（qE-TD）的生理重要性已被广泛接受，但尚不清楚有多少吸收的光能通过 qE 相关机制耗散。在这项研究中，通过使用 RNA 干扰（RNAi）沉默 psbS 基因的转基因水稻中的典型能量分配模型，定量估计了 PSII 中与不同 TD 过程（包括 qE-TD）相关的吸收光能量的命运。psbS 基因的沉默导致 TD 的光诱导部分减少，而在广泛的光强范围内，能量分配到电子传递中并没有改变。分配模型表明，在饱和光下分配给 qE-TD 的能量为 30-50%。我们还表明，大部分吸收的光能以与 qE 无关的方式进行热耗散。讨论了这种耗散的性质。
