ABSTRACT
Conclusions and Perspectives ........................................................................................................ 422 Abbreviations ................................................................................................................................. 422 References ...................................................................................................................................... 423
Since the emergence of life on Earth, the food chains depend on the use of solar energy by photosyntheticorganisms.Onecharacteristicfeatureoftheseorganismsresidesintheirgloballackofmobility,eventhoughtmicroalgaecanmoveinthewatercolumn.Consequently,thistypeoforganisms cannotrunawayfromthealterationsintheirbioticand/orabioticenvironments,includingdecienciesorexcessesoflightornutrients.Tocopewiththesealterations,photosyntheticcellsactivatedifferent types of defense mechanisms, including reorientations of the plastid metabolism. Because the rapidityandefciencyoftheresponsesdifferamongspeciesorevenplantcultivars,thisaptitudeto adapttounfavorableconditionsconstitutesamajorfactorfortheirsurvival(Külheimet al.2002). Forinstance,sun-grownleavesexhibitagreaterabilitytoactivatephotoprotectivemechanism,such asthexanthophyllcycle,thanshade-grownplantswhenbothtypesofplantsareexposedtohigh light (Demmig-Adams and Adams 1994, 1995, 2006).
