Department of Microbiology, Miami University, Oxford, OH, 45056, USA.
Department of Biology, University of Southern California, Los Angeles, CA, 90089, USA.
Photosynth Res. 2023 Sep;157(2-3):65-84. doi: 10.1007/s11120-023-01032-y. Epub 2023 Jun 22.
While PSI-driven cyclic electron flow (CEF) and assembly of thylakoid supercomplexes have been described in model organisms like Chlamydomonas reinhardtii, open questions remain regarding their contributions to survival under long-term stress. The Antarctic halophyte, C. priscuii UWO241 (UWO241), possesses constitutive high CEF rates and a stable PSI-supercomplex as a consequence of adaptation to permanent low temperatures and high salinity. To understand whether CEF represents a broader acclimation strategy to short- and long-term stress, we compared high salt acclimation between the halotolerant UWO241, the salt-sensitive model, C. reinhardtii, and a moderately halotolerant Antarctic green alga, C. sp. ICE-MDV (ICE-MDV). CEF was activated under high salt and associated with increased non-photochemical quenching in all three Chlamydomonas species. Furthermore, high salt-acclimated cells of either strain formed a PSI-supercomplex, while state transition capacity was attenuated. How the CEF-associated PSI-supercomplex interferes with state transition response is not yet known. We present a model for interaction between PSI-supercomplex formation, state transitions, and the important role of CEF for survival during long-term exposure to high salt.
尽管已在模式生物如莱茵衣藻中描述了 PSI 驱动的循环电子流 (CEF) 和类囊体超复合物的组装，但它们对长期胁迫下生存的贡献仍存在一些问题。南极盐生植物 C. priscuii UWO241（UWO241）由于适应永久低温和高盐度，具有组成型的高 CEF 速率和稳定的 PSI-超复合物。为了了解 CEF 是否代表一种更广泛的短期和长期胁迫适应策略，我们比较了耐盐的 UWO241、盐敏感的模式生物 C. reinhardtii 和中度耐盐的南极绿藻 C. sp. ICE-MDV（ICE-MDV）之间的高盐适应。在所有三种衣藻中，CEF 在高盐下被激活，并伴随着非光化学猝灭的增加。此外，高盐适应的两种菌株的细胞都形成了 PSI-超复合物，而状态转换能力被削弱。CEF 相关的 PSI-超复合物如何干扰状态转换反应尚不清楚。我们提出了一个模型，用于解释 PSI-超复合物形成、状态转换以及 CEF 在长期暴露于高盐下生存中的重要作用之间的相互作用。
