Distribution and levels of phytoecdysteroids in plants of the genus Silene during development

The purpose of the present work is the study of ecdysteroid distribution in annual and perennial Silene species during development. The experimental approach included the measurement of ecdysteroid levels in different plant organs and an evaluation of the contribution of individual organs to the total amount of 20-hydroxyecdysone (20E) produced by the plant. The highest concentrations of 20E were observed in reproductive organs. High levels were also found in leaves with lower levels in stems. Maximal ecdysteroid content for aerial parts was observed during periods of intense growth: at budding or flowering in annual species, and during vegetative growth or budding in perennial species. The contribution of the different organs to the overall ecdysteroid content changes during plant development. Leaves represent the main part of plant mass and 20E content. Reproductive organs represent a relatively small mass, but they contain high concentrations of ecdysteroids and, in terms of the amount of 20E they contain, their contribution is equal to that of stems. Arch. Insect Biochem. Physiol. 43:1-8, 2000. (C) 2000 Wiley-Liss, Inc.