How do vascular plants perform photosynthesis in extreme environments? An integrative ecophysiological and biochemical story

• Published in: The Plant journal : for cell and molecular biology Vol. 101; no. 4; pp. 979 - 1000
• Main Authors: Fernández‐Marín, Beatriz, Gulías, Javier, Figueroa, Carlos M., Iñiguez, Concepción, Clemente‐Moreno, María J., Nunes‐Nesi, Adriano, Fernie, Alisdair R., Cavieres, Lohengrin A., Bravo, León A., García‐Plazaola, José I., Gago, Jorge
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.02.2020
• Subjects: Adaptation; Adaptation, Biological; Antioxidants - metabolism; Biological evolution; Carbon; Carbon fixation; Carboxylation; Cell walls; chloroplast ultrastructure; Chloroplasts - ultrastructure; Conductance; Desert Climate; Ecosystem; Electron Transport; Extreme Environments; Fieldwork; Flowers & plants; Membrane composition; Mesophyll; mesophyll conductance; Molecular modelling; Photochemicals; Photosynthesis; Photosynthesis - physiology; photosynthetic pigments; Physiology; Plant Leaves - anatomy & histology; Plant Leaves - metabolism; Plant Leaves - physiology; Plant Physiological Phenomena; Plant species; Plants; Plants - chemistry; Plants - metabolism; Reactive oxygen species; Resistance; Ribulose-bisphosphate carboxylase; Ribulose-Bisphosphate Carboxylase - metabolism; RuBisCO; Scavenging; Secondary Metabolism; Stomata; Stomatal conductance; VAZ; stomatal conductance; mesophyll conductance; RuBisCO; VAZ; chloroplast ultrastructure; photosynthetic pigments
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14694

Summary 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. Significance Statement The molecular and physiological mechanisms that drive photosynthesis in vascular species from extreme environments still remain largely unknown. Here we review the different adaptations (from the whole plant to the molecular level) that enable plants to succeed and sustain an annual positive carbon balance under the typical short and harsh growing seasons in these environments.