Effect of brassinosteroids on growth and proton extrusion in the alga Chlorella vulgaris Beijerinck (Chlorophyceae)

Brassinolide, as a plant hormone, promotes growth of a number of plant species. Similar effects are induced by its epimer 24-epibrassinolide. In this paper we discuss the effects of brassinosteroids on the growth and proton extrusion in the green alga Chlorella vulgaris (Chlorophyceae). At concentrations between 10(-15) and 10(-8) M, brassinolide and 24-epibrassinolide induce a significant stimulation of growth and H+ extrusion. The growth was associated with an increase in the capability of algal cells to acidify the medium, where brassinolide is biologically more active than 24-epibrassinolide.