Functions of Carotenoids in Leaves of Higher Plants (Review)

The structural diversity and multifunctionality of carotenoids remains an important problem for many areas of biology and medicine. Interactions between carotenoids in cyclic reactions provided an understanding of their role in redox processes and their participation in the basic physicochemical, physiological, and biochemical functions of plants. This review analyzes the contribution of carotenoids to the formation of the photosynthetic apparatus (PSA) structure in plants, as well as their participation in the light-energy absorption and the protection of chlorophyll molecules from reactive oxygen species. The mechanisms of zeaxanthin involvement in the energy-dissipation process and the protective role of carotenoids as antioxidants in the lipid phase of membranes are reviewed. The function of violaxanthin-cycle (VC) pigments in water-photolysis reactions is discussed in relation to their participation in the utilization of released oxygen. A hypothesis about the involvement of balance transformations of VC pigments under subthreshold illumination in the maintenance of “plant memory” mechanisms upon a switch to high illumination is proposed. Environmental studies show that the mechanism of PSA photoprotection, which is associated with the activation of non-photochemical quenching as a part of nonspecific plant responses, is activated in response to a wide range of stress factors.