The Antarctic green alga Chlamydomonas sp. UWO 241 (UWO 241) is adapted to permanent low temperatures, hypersalinity, and extreme shade. One of the most striking phenotypes of UWO 241 is an altered PSI organization and constitutive PSI cyclic electron flow (CEF). To date, little attention has been paid to CEF during long-term stress acclimation, and the consequences of sustained CEF in UWO 241 are not known. In this study, we combined photobiology, proteomics, and metabolomics to understand the underlying role of sustained CEF in high-salinity stress acclimation. High salt-grown UWO 241 exhibited increased thylakoid proton motive flux and an increased capacity for nonphotochemical quenching. Under high salt, a significant proportion of the up-regulated enzymes were associated with the Calvin-Benson-Bassham cycle, carbon storage metabolism, and protein translation. Two key enzymes of the shikimate pathway, 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase and chorismate synthase, were also up-regulated, as well as indole-3-glycerol phosphate synthase, an enzyme involved in the biosynthesis of l-Trp and indole acetic acid. In addition, several compatible solutes (glycerol, Pro, and Suc) accumulated to high levels in high salt-grown UWO 241 cultures. We suggest that UWO 241 maintains constitutively high CEF through the associated PSI-cytochrome b₆f supercomplex to support robust growth and strong photosynthetic capacity under a constant growth regime of low temperatures and high salinity.

南极绿藻衣藻sp。UWO 241（UWO 241）适用于永久低温，高盐度和极端阴影。UWO 241最引人注目的表型之一是改变的PSI组织和本构性PSI循环电子流（CEF）。迄今为止，长期的压力适应过程中对CEF的关注很少，UWO 241中持续CEF的后果尚不清楚。在这项研究中，我们结合了光生物学，蛋白质组学和代谢组学的知识，以了解持续CEF在高盐度压力适应中的潜在作用。高盐生长的UWO 241表现出类囊体质子运动通量的增加和非光化学猝灭能力的提高。在高盐下，大量的上调酶与Calvin-Benson-Bassham循环，碳储存代谢和蛋白质翻译有关。d上调了-阿拉伯庚酮磺酸7-磷酸合酶和分支酸合酶以及吲哚3-甘油磷酸合酶（一种参与生物合成的酶）。 升-Trp和吲哚乙酸。另外，在高盐生长的UWO 241培养物中，几种相容性溶质（甘油，Pro和Suc）积累了很高的水平。我们建议UWO 241通过相关的PSI-细胞色素b ₆ f超复合物维持组成性较高的CEF，以在低温和高盐度的恒定生长机制下支持强劲的生长和强大的光合能力。