Investigation of light energy redistribution mechanisms under stress environments in the moss Physcomitrella patens

为了在波动的光环境下维持有效的光化学反应，吸收的光能必须在叶绿体类囊体膜中的光系统I和光系统II （PSI和PSII）之间重新分配。在这项研究中，我们研究了一种新发现的光收集复合物（LHC）蛋白Lhcb9在苔藓小立藓（Physcomitrella patens）中的能量再分配机制。我们的研究结果表明，两种不同类型的PSI超复合物存在于patens类囊体膜中，Lhcb9是形成更大的PSI超复合物所必需的。此外，我们还证明了Lhcb9参与了强光条件下PSI超配合物功能天线尺寸的调节。研究结果表明，Lhcb9对可调PSI光收集系统在进化过程中攻克水陆动态环境界面具有重要意义。

To maintain the efficient photochemistry under fluctuating light environments, absorbed light energy has to be redistributed between photosystem I and II (PSI and PSII) in chloroplast thylakoid membranes. In this study, we investigated the energy redistribution mechanism of a recently discovered light-harvesting complex (LHC) protein, Lhcb9, in the moss Physcomitrella patens. Our results indicated that two different types of PSI supercomplex exist in P. patens thylakoid membranes, and Lhcb9 is essential for the formation of the larger PSI supercomplex. Moreover, we demonstrated that Lhcb9 is involved in the adjustment of the functional antenna size of PSI supercomplex under high light conditions. Our results implied that Lhcb9 is important for the adjustable PSI light-harvesting system for conquering dynamic environmental interface between aquatic and terrestrial conditions during the evolution.