Effect of brassinosteroids on nucleic acids and protein content in cultured cells of Chlorella vulgaris

This study was conducted to investigate changes of nucleic acids and protein levels in response to brassinosteroid (BR) effect in the green alga Chlorella vulgaris Beijerinck. BRs had the greatest effect on growth and metabolism of algae between 24 and 36 h after treatment in the range from 10(-12) to 10(-8) M. The highest growth of the content of nucleic acids and proteins was observed in the case of brassinolide (BL) at the concentration 10(-8) M in the 36th hour of cultivation. BL and its derivatives are biologically more active than castasterone (CS). The lowest stimulatory activity was shown by homoCS. The stimulatory effect of BRs in the algae was arranged in the following order: BL > 24-epiBL > homoBL > CS > 24-epiCS > homoCS. The relationship between the structure and the biological activity of BRs in stimulation of growth and changes in the content of DNA, RNA and proteins are discussed. (C) 2000 Editions scientifiques et medicales Elsevier SAS.