251 Chapter 12 Heat Stress: Susceptibility, Recovery and Regulation Prasanna Mohanty Regional Plant Resource Center , Nayapalli, Bhubaneswar 751015, India; Jawaharlal Nehru University , New Delhi 11006, India Vladimir D. Kreslavski and Vyacheslav V. Klimov Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia Dmitry A. Los Institute of Plant Physiology , Russian Academy of Sciences, Moscow 127276, Russia Mamoru Mimuro* Graduate School of Human and Environmental Studies, Kyoto University , Kyoto 606-8501, Japan Robert Carpentier Groupe de Recherche en Biologie Végétale, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada Suleyman I. Allakhverdiev** Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region 142290, Russia; Institute of Plant Physiology , Russian Academy of Sciences, Moscow 127276, Russia *He is deceased. He lived from June 17, 1949 to February 8, 2011 **Author for correspondence, e-mail: suleyman20042000@yahoo.com; suleyman@issp.serpukhov.su Summary ................................................................................................................................................................ 252 I. Introduction ....................................................................................................................................................... 252 II. High Temperature Stress .................................................................................................................................. 253 A. Heat Stress: Early Events ................................................................................................................. 255 B. The Fragility of Photosystem II (PS II)............................................................................................... 255 C. Heat Stress: Oxidant and Antioxidant Balance.................................................................................. 256 D. Post-Heat Stress Recovery ............................................................................................................... 258 III. Role of Cofactors, Extrinsic Proteins of PS II and Heat-Shock Proteins in Thermal Damage ........................... 258 A. The Heat-Shock Proteins and Extrinsic Proteins of the Oxygen-Evolving Complex .......................... 258 B. Heat-Stress-Inducible Genes in Synechocystis sp. PCC 6803 ......................................................... 259 IV. Membrane Fluidity and Heat Sensors .............................................................................................................. 261 A. Membrane Fluidity and its Role in the Perception of Environmental Signals .................................... 261 B. Membrane Lipids .............................................................................................................................. 262 J.J. Eaton-Rye, B.C. Tripathy and T.D. Sharkey (eds.), Photosynthesis: Plastid Biology, Energy Conversion and Carbon Assimilation, Advances in Photosynthesis and Respiration 34, pp. 251–274, DOI 10.1007/978-94-007-1579-0_12, © Springer Science+Business Media B.V. 2012