Changes in Formation and Localization of Phenolic Compounds in the Tissues of European and Canadian Yew during Dedifferentiation <Emphasis Type="Italic">In Vitro</Emphasis>

Changes in formation and localizations of phenolic compounds, including flavans, were investigated in the tissues of European and Canadian yew (Taxus baccata L. and T. canadensis Marsh.) during dedifferentiation in vitro. Annual shoots of European yew had the highest capacity for synthesizing these compounds. During the summer growth period, the content of total soluble phenolic compounds and flavans in these shoots was 30–40% higher than in the winter. Cell dedifferentiation and growth in vitro was accompanied by enhanced synthesis of phenolic compounds, including flavans, the change in tissue localization of these compounds, and an increase in the number of cells containing phenolics. Significant accumulation of phenolic compounds in callus cells resulted in necroses following two subcultures in the European and Canadian yew cultures initiated from summer explants, and following seven subcultures of the European yew calli initiated from winter explants. These data allow us to suggest that a high level of phenolic compounds in yew calli could be the reason for their necrosis.     

Effect of Ultraviolet (UV-B) Radiation on the Formation and Localization of Phenolic Compounds in Tea Plant Callus Cultures

The effect of ultraviolet (UV-B) radiation on the accumulation and tissue localization of phenolic compounds in two strains of callus cultures of tea plant (Camellia sinensisL.) were investigated. The strains differed in their morphological and physiological characteristics and biosynthetic capacity. UV-B radiation hampered culture growth, decreased the size of callus-forming cells and promoted the accumulation of soluble and, to a lesser extent, polymeric forms of phenolic compounds, such as lignin. This accumulation was accompanied by an increase in the phenolic compound deposition in cell walls and intercellular space and by deposition of a lignin-like material on the surface of callus cultures. The strain characterized by an increased formation of phenolic compounds was more resistant to UV-B radiation as compared to that with lower phenolic productivity.     

Formation of Phenolic Compounds in Apogeotropic Roots of Cycad Plants

Formation and location of phenolic compounds in apogeotropic roots (coralloid roots) were studied in six cycad species, which belong to the genera Cycas, Encephalartos, and Ceratozamia. Total contents of soluble phenolic compounds in coralloid roots in all species studied varied insignificantly, with except for Ceratozamia mexicana that accumulated three times higher amounts of phenolic compounds. Phenolic compounds were accumulated in cell walls of cortical parenchyma of coralloid roots, in intercellular spaces, and in specialized storage cells, found in all zones of apogeotropic roots. The greatest number of phenol-storing cells was situated in the cortical parenchyma of the central part of coralloid roots, adjacent to a zone where active symbiotic cyanobacteria were localized, and in the coralloid root basal region lacking viable forms of cyanobionts. It was suggested that phenolic compounds affect the formation of symbiosis between cyanobacteria and apogeotropic roots of cycad plants, as well as their metabolism.