Suppression of Wolffia arrhiza growth by brassinazole, an inhibitor of brassinosteroid biosynthesis and its restoration by endogenous 24-epibrassinolide

The effect of 24-epibrassinolide (epiBL) (10−13-10−6 M) and brassinazole (Brz2001) (10−6-10−4 M), a specific brassinosteroid biosynthesis inhibitor, on growth and levels of chlorophylls, carotenoids, sugars and protein in Wolffia arrhiza after 7 days of cultivation is reported. Application of epiBL (10−12-10−7 M) to W. arrhiza cultures stimulates the growth and chemical composition. The greatest effect of epiBL is observed at a concentration of 10−9 M. Addition of Brz2001 to W. arrhiza cultures inhibits their growth. This inhibition of growth could be reversed by the addition of epiBL.