LHCII PROTEIN PHOSPHORYLATION IN LEAVES OF ARABIDOPS1S THALIANA MUTANTS DEFICIENT IN NON-PHOTOCHEMICAL QUENCHING

摘要

Light reactions generate reactive intermediates and oxygen species that potentially damage photosynthetic machinery, especially in excess light. To prevent the detrimental effects of damaging substances, plants have evolved a number of protection mechanisms -including antioxidant systems and processes for thermal dissipation of light energy. Thermal dissipation in PSII can be measured as quenching of chlorophyll fluorescence in PSII. Characterization of the mutants deficient in non-photochemical quenching (NPQ) has shown that besides the acidification stage of thylakoid lumen, the de-epoxidized xanthophylls and the psbS protein are involved in formation of NPQ (Niyogi et al 1998, Li et al 2000, 2002). npq1 mutants cannot form zeaxanthin in excess light, which results in reduced NPQ and pronounced lipid peroxidation (Havaux & Niyogi 1999), while npq4 mutants typically show strong reduction in NPQ due to deletion or modification of PsbS gene (Li et al 2000, 2002).