Shedding some light on cold acclimation, cold adaptation, and phenotypic plasticity

In the past, the role of light as an energy source was largely ignored in research focused on cold acclimation and freezing tolerance in plants. However, cold acclimation is an energy-requiring process. We summarize research illustrating that photoautrophs as diverse as cyanobacteria (Plectonema boryanum), green algae (Chlorella vulgaris, Dunaliella salina, Chlamydomonas raudensis), crop plants (Triticum aestivum L., Secale cereale L., Brassica napus L.), and conifers (Pinus banksiana) L.) tailor the structure and function of the photosynthetic apparatus to changes in temperature and irradiance to maintain cellular energy balance called photostasis. Modulation of either temperature or irradiance results in a similar imbalance in cellular energy that is sensed through changes in chloroplastic excitation pressure. Thus, concepts of photostasis and excitation pressure provide the context through which one can explain the congruence of phenotypic plasticity and photosynthetic performance associated with cold acclimation and photoacclimation. Photosynthetic organisms can sense changes in temperature and irradiance through modulation of the redox state of the photosynthetic electron transport chain, which, in turn, governs phenotype through the regulation of nuclear gene expression and chloroplast biogenesis. We suggest that elucidation of the molecular mechanism(s) by which excitation pressure regulates phenotypic plasticity and photosynthetic performance will be essential in addressing the challenge of maintaining or perhaps enhancing crop productivity under the suboptimal growth conditions predicted to occur as a consequence of climate change. Key words: algae, cold acclimation, cyanobacteria, excitation pressure, phenotypic plasticity, photoacclimation, photostasis, plants. Auparavant, on ignorait largement le role de la lumiere comme source d'energie dans les recherches portant sur l'acclimatation au froid et la tolerance au gel. Cependant, l'acclimatation au froid constitue un processus demandant de l'energie. L'auteur resume la recherche, illustrant que des autotrophes aussi diversifies que les cyanobacteries (Plectonema boryanum), les algues vertes (Chlorella vulgaris, Dunaliella salina, Chlamydomonas raudensis), les plantes cultivees (Triticum aestivum L., Secale cereale L., Brassica napus L.), et les coniferes (Pinus banksiana) L.), ajustent la structure et la fonction de leurs appareils photosynthetiques selon les changements de temperature et d'irradiance pour maintenir la balance energetique cellulaire appelee photostasie. Une modulation de la temperature ou de l'irradiance induit un debalancement similaire dans l'energie cellulaire lequel est percu par des changements dans la pression d'excitation chloroplastique. Ainsi, les concepts de photostasie et de pression d'excitation fournissent le contexte dans lequel on peut expliquer la congruence de la plasticite phenotypique et de la performance photosynthetique associees a l'acclimatation au froid et la photoacclimatation. Les organismes photosynthetiques peuvent percevoir les changements de temperature et d'irradiance par la modulation de l'etat redox de la chaine de transport des electrons photosynthetiques, laquelle a son tour gouverne le phenotype par la regulation de l'expression des genes de la biogenese des chloroplastes. L'auteur suggere que l'elucidation du ou des mecanismes cellulaires par lesquels la pression d'excitation regle la plasticite phenotypique et la performance photosynthetique sera essentielle pour faire face au defi de maintenir et possiblement augmenter la productivite des recoltes sous des conditions de croissance suboptimales, tel que prevu comme consequence du changement climatique. [Traduit par la Redaction] Mots-cles : algue, acclimatation au froid, cyanobacteries, pression d'excitation, plasticite phenotypique, photoacclimatation, photostasie, plantes.
Introduction Historically, the role of light, energy trapping, and transformation through photosynthesis was, by and large, ignored in research focused on cold acclimation and freezing tolerance of plants even though [...]