In this work, we review the physiological and molecular mechanisms that allow vascular plants to perform photosynthesis in extreme environments, such as deserts, polar and alpine ecosystems. Specifically, we discuss the morpho/anatomical, photochemical and metabolic adaptive processes that enable a positive carbon balance in photosynthetic tissues under extreme temperatures and/or severe water-limiting conditions in C3 species. Nevertheless, only a few studies have described the in situ functioning of photoprotection in plants from extreme environments, given the intrinsic difficulties of fieldwork in remote places. However, they cover a substantial geographical and functional range, which allowed us to describe some general trends. In general, photoprotection relies on the same mechanisms as those operating in the remaining plant species, ranging from enhanced morphological photoprotection to increased scavenging of oxidative products such as reactive oxygen species. Much less information is available about the main physiological and biochemical drivers of photosynthesis: stomatal conductance (gs ), mesophyll conductance (gm ) and carbon fixation, mostly driven by RuBisCO carboxylation. Extreme environments shape adaptations in structures, such as cell wall and membrane composition, the concentration and activation state of Calvin-Benson cycle enzymes, and RuBisCO evolution, optimizing kinetic traits to ensure functionality. Altogether, these species display a combination of rearrangements, from the whole-plant level to the molecular scale, to sustain a positive carbon balance in some of the most hostile environments on Earth.

中文翻译：

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维管束植物在极端环境中如何进行光合作用？生态生理生化综合报道。

在这项工作中，我们回顾了允许维管植物在极端环境（例如沙漠，极地和高山生态系统）中进行光合作用的生理和分子机制。具体来说，我们讨论了形态/解剖，光化学和代谢适应性过程，这些过程使C3物种在极端温度和/或严厉限水条件下，能够在光合组织中实现正碳平衡。然而，鉴于在偏远地区实地调查的固有困难，仅有极少的研究描述了植物在极端环境下的光保护作用。但是，它们涵盖了相当大的地理和功能范围，这使我们能够描述一些总体趋势。通常，光保护依赖于与其余植物物种相同的机制，从增强的形态光保护作用到增加清除氧化性产物（如活性氧）的范围。关于光合作用的主要生理和生化驱动因素的信息很少，主要是由RuBisCO羧化作用驱动的气孔电导（gs），叶肉电导（gm）和碳固定。极端环境会影响结构的适应性，例如细胞壁和膜的组成，Calvin-Benson循环酶的浓度和激活状态以及RuBisCO的进化，从而优化动力学特性以确保功能。这些物种总共显示出从整个植物水平到分子规模的重排组合，以在地球上某些最不利的环境中维持正碳平衡。