Mosses are one of the earliest land plants that diverged from fresh-water green algae. They are considered to have acquired a higher capacity for thermal energy dissipation to cope with dynamically changing solar irradiance by utilizing both the "algal-type" light-harvesting complex stress-related (LHCSR)-dependent and the "plant-type" PsbS-dependent mechanisms. It is hypothesized that the formation of photosystem (PS) I and II megacomplex is another mechanism to protect photosynthetic machinery from strong irradiance. Herein, we describe the analysis of the PSI-PSII megacomplex from the model moss, Physcomitrella patens, which was resolved using large-pore clear-native polyacrylamide gel electrophoresis (lpCN-PAGE). The similarity in the migration distance of the Physcomitrella PSI-PSII megacomplex to the Arabidopsis megacomplex shown during lpCN-PAGE suggested that the Physcomitrella PSI-PSII and Arabidopsis megacomplexes have similar structures. Time-resolved chlorophyll fluorescence measurements show that excitation energy was rapidly and efficiently transferred from PSII to PSI, providing evidence of an ordered association of the two photosystems. We also found that LHCSR and PsbS co-migrated with the Physcomitrella PSI-PSII megacomplex. The megacomplex showed pH-dependent chlorophyll fluorescence quenching, which may have been induced by LHCSR and/or PsbS proteins with the collaboration of zeaxanthin. We discuss the mechanism that regulates the energy distribution balance between two photosystems in Physcomitrella.

中文翻译：

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在苔藓小立碗藓中形成包含LHCSR和PsbS的PSI-PSII大型复合体。

苔藓是最早与淡水绿藻分离的陆地植物之一。通过利用“藻类”依赖光的复杂应力相关（LHCSR）和“植物型” PsbS-，它们被认为具有更高的散热能力，以应对动态变化的太阳辐照度。依赖机制。据推测，光系统（PS）I和II巨型复合物的形成是保护光合作用机械免受强辐射的另一种机制。在这里，我们描述了从模型苔藓，Physcomitrella patens模型对PSI-PSII巨型复合物的分析，该分析是使用大孔透明本征聚丙烯酰胺凝胶电泳（lpCN-PAGE）进行解析的。在lpCN-PAGE中显示的拟小体PSI-PSII大复合体与拟南芥大复合体的迁移距离相似，表明拟小体PSI-PSII和拟南芥大复合体具有相似的结构。时间分辨的叶绿素荧光测量结果表明，激发能快速有效地从PSII转移到PSI，提供了两个光系统有序关联的证据。我们还发现LHCSR和PsbS与Physcomitrella PSI-PSII大型复合体共同迁移。巨型复合物显示出pH依赖性的叶绿素荧光猝灭，这可能是由玉米黄质的协同作用由LHCSR和/或PsbS蛋白诱导的。我们讨论了调节Physcomitrella中两个光系统之间能量分配平衡的机制。