No abstract

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.

No abstract

David Iosifovich Sapozhnikov (17.06.1911-23.11.1983), a well known plant physiologist and evolutionist would have been 100 this year. Sapozhnikov investigated the role of carotenoids in plant life and acquired worldwide recognition for his discovery of the violaxanthin cycle. This review considers the most important Sapozhnikov's results and hypotheses elaborated by subsequent research, as well as the modern concepts in this area of investigation.Abbreviations: Ax-antheraxanthin; NPQ-non photochemical quenching of chlorophyll fluorescence; PSII-photosystem II; VC-violaxanthin cycle; VDE-violaxanthin deepoxidase; Vxviolaxanthin; ZE-zeaxanthin epoxidase; Zx-zeaxanthin.

Изучены показатели пигментного комплекса у 112 видов растений Монголии, обитающих в широком диапазоне экотопических условий зональных и интразональных экосистем (сухие, горные и пустынные степи, разные типы пустынь, оазисы, пойменные луга). Результаты анализа разнообразия пигментного комплекса свидетельствуют о видоспецифичности величин содержания хлорофилла и фотосинтетического потенциала. Они определяются совокупностью признаков разной природы. Прежде всего — это жизненная форма с ее экологическими и стратегическими свойствами, а также эдафические факторы — влагообеспеченность, почвенное плодородие, солевой режим и факторы климата — осадки, освещенность и температура в современный период и в режимах формирования видов в историческом прошлом. Обсуждается полифункциональная роль светособирающего комплекса при адаптации растений к лимитирующему и стрессовому режиму солнечной радиации.