Chloroplasts and Strong Photoprotective Mechanisms

The exposure of plants to high light in excess of photosynthetic needs causes a reduction in photosynthetic capacity, which is known as photoinhibition. During photoinhibition reactive oxygen species are produced to an extent that leads to the destruction of carotenoids, chlorophyll, protein and to an increase in membrane lipid peroxidation. Plants have developed several strategies to sustain chloroplast functioning under high light conditions. In this review we summarize the latest knowledge about mechanisms for photoinhibition and photoprotective strategies such as: 1) chloroplast antioxidant systems (i.e. tocochromanols, water-water cycle); 2) the quenching of the triplet chlorophyll and reactive oxygen species by carotenoids.; 3) the reversible conversion of violxanthin to zeaxanthin in the light-harvesting complex (LHC) (xanthophyll cycles).