Molecular mechanisms involved in plant photoprotection

Abstract

Photosynthesis uses sunlight to convert water and carbon dioxide into biomass and oxygen. When in excess, light can be dangerous for the photosynthetic apparatus because it can cause photo-oxidative damage and decreases the efficiency of photosynthesis because of photoinhibition. Plants have evolved many photoprotective mechanisms in order to face reactive oxygen species production and thus avoid photoinhibition. These mechanisms include quenching of singlet and triplet excited states of chlorophyll, synthesis of antioxidant molecules and enzymes and repair processes for damaged photosystem II and photosystem I reaction centers. This review focuses on the mechanisms involved in photoprotection of chloroplasts through dissipation of energy absorbed in excess.

Diversity in Xanthophyll Cycle Pigments Content and Related Nonphotochemical Quenching (NPQ) Among Microalgae: Implications for Growth Strategy and Ecology

“…The regulation of the XC and mediated NPQ at the molecular level has been the object of intense research in various photosynthetic organisms (see the recent syntheses by Niyogi and Truong , Demmig‐Adams et al. , Goss and Lepetit , Magdaong and Blankenship , Pinnola and Bassi ). In microalgae, its peculiarities have been extensively studied in green representatives (Finazzi and Minagawa , Erickson et al.…”

Microsecond and millisecond dynamics in the photosynthetic protein LHCSR1 observed by single-molecule correlation spectroscopy

“…Under high light (sunny), LHCs also dissipate excess energy as heat through a process known as nonphotochemical quenching (NPQ), which is activated by conformational changes (14,15). In unicellular algae and mosses, Light-Harvesting Complex Stress Related 1 (LHCSR1) is the LHC responsible for dissipation (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27). Single-molecule spectroscopy of LHCSR1 revealed frequent transitions between bright (photoactive) and dim (quenched) states (9).…”

β-cyclocitric acid: a new apocarotenoid eliciting drought tolerance in plants

“…drought, cold or pathogens), which inhibit the photosynthetic activity, light energy can be absorbed in excess to what can be used by the photosynthetic processes, hence favoring transfer of electrons or excitation to oxygen and leading to ROS formation 3,4 . Singlet oxygen is produced from triplet-excited chlorophylls, mainly in the PSII reaction centers 5–8 . In fact, the PSII centers bind several β-carotene molecules that can scavenge 1 O 2 molecules generated therein 5,9 .…”

“…Singlet oxygen is produced from triplet-excited chlorophylls, mainly in the PSII reaction centers 5–8 . In fact, the PSII centers bind several β-carotene molecules that can scavenge 1 O 2 molecules generated therein 5,9 . 1 O 2 quenching by carotenoids proceeds by a physical mechanism that leads to thermal energy dissipation 10 and also through a chemical quenching mechanism involving direct oxidation of the carotenoid molecule by 1 O 2 2,5,11 .…”

“…In fact, the PSII centers bind several β-carotene molecules that can scavenge 1 O 2 molecules generated therein 5,9 . 1 O 2 quenching by carotenoids proceeds by a physical mechanism that leads to thermal energy dissipation 10 and also through a chemical quenching mechanism involving direct oxidation of the carotenoid molecule by 1 O 2 2,5,11 . Thus, as a major site of 1 O 2 production, PSII is also a major generator of oxidized β-carotene metabolites such as β-CC.…”