β-CC	β-cyclocitral
1Chl, 1Chl* and 3Chl	respectively, singlet state, singlet excited state and triplet excited state of chlorophyll
1O2	singlet oxygen (1∆gO2)
2-Cys PRX	two-cysteine peroxiredoxin
A	acceptor
A1	phylloquinone of PSI
APX	ascorbate peroxidase
AscH2	ascorbate, ascorbic acid
Car and 3Car	respectively, singlet and triplet state of carotenoid
CAT	catalase
Chl and Chl*	respectively, chlorophyll and excited chlorophyll
Chl a	chlorophyll a
cyt	cytochrome
cyt b559	cytochrome b559
Cyt b6f	cytochrome b6/f complex
DBMIB	2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone
DCMU	3-(3,4-di-chlorophenyl)-1,1-dimethyl urea
DHA	dehydroascorbate; DMF, dimethylformamide
DNP-INT	2-(2,4-dinitrophenoxy)-3-iodo-4-methyl-1-(1-methylethyl)-5-nitro-benzene
Em	midpoint redox potential
E0′	standard redox potential
EPR	electron paramagnetic resonance
EX1	Executer1
Fd, Fdox and Fdred	ferredoxin, and oxidized and reduced ferredoxin, respectively
FL	flavin
FL•−	anion form of flavin semiquinone
FLH•	flavin semiquinone radical
FLHOOH	flavin hydroperoxide
FLU	a protein important in control of chlorophyll biosynthesis
FNR	ferredoxin-NADP+ reductase
FtsH	a protease involved in PSII repair; FX, FA, and FB, 4Fe-4S clusters of PSI
GSH	reduced glutathione
GSSG	glutathione disulfide
H2O2	hydrogen peroxide
HO•	hydroxyl radical
HO2•	hydroperoxyl radical
HO2−	hydroperoxyl anion
HP, IP, LP and VLP	respectively, high, intermediate, low and very low potential forms of cytochrome b559
hν	energy of a photon
ISC	intersystem crossing
kforward and kreverse•	forward and reverse rate constant, respectively
LHC	light harvesting complex; LHCI and LHCII, respectively, light harvesting complex of PSI and PSII
LOO•	lipid peroxyl radical; M, metal
MDA	monodehydroascorbate
MDAR	monodehydroascorbate reductase
MenB	1,4-hydroxynaphthoyl-coenzyme A synthase
NHE	Normal Hydrogen Electrode
NPQ	non-photochemical quenching of excitation energy
O2	molecular oxygen (3Σ+gO2); O3, ozone
O2•−	superoxide anion radical
OEC	oxygen-evolving complex
P680	primary donor of PSII
P700	primary donor of PSI
PAP	phosphoadenosine phosphate
PC	plastocyanin
PCD	programmed cell death
PETC	photosynthetic electron transport chain
Pheo	pheophytin
PheoD1 and PheoD2	respectively, pheophytins bound to D1 and D2 proteins of PSII
PPFD	photosynthetic photon flux density
PQ	plastoquinone
PQ•−	plastosemiquinone anion radical
PQH2	plastoquinol
PRX	peroxiredoxin; PSI and PSII, Photosystems I and II, respectively
PsbS	a chloroplast-localized protein required for NPQ
PTOX	plastid terminal oxidase
PX	peroxidase
Q	quinone
Q•−	semiquinone anion radical
R•	organic radical
RC	reaction center
ROO•	peroxyl radical
ROOH	organic peroxide
ROOOOR	linear tetraoxide
ROS	reactive oxygen species
RS	thiol
rubisco	ribulose-1,5-bisphosphate carboxylase oxygenase
S	sensitizer
SAL1	an inositol polyphosphate phosphatase
SOD	superoxide dismutase
TRX	thioredoxin
TyrZ	the redox active tyrosine of PSII