The influence of animal sex hormones on the induction of flowering in Arabidopsis thaliana:: comparison with the effect of 24-epibrassinolide

The influence of selected steroids on the in vitro generative development of Arabidopsis thaliana was investigated. The activity of the animal steroids androsterone, androstenedione, progesterone, estrone, estriol, and 17beta-estradiol was compared to 24-epibrassinolide, a member of the regulatory family of brassinosteroids. A. thaliana plants were cultured in vitro in media containing these steroids. The stimulatory effect of the tested substances was evaluated by measurement of the percentage of generative plants versus vegetative plants in the experimental group. It was established that androstenedione, the main testosterone precursor, and androsterone, a typical male hormone, were more effective in stimulating flowering in A. thaliana than the female hormones, estrogens and progesterone. Androsterone at a concentration of 0.1 muM increased the percentage of generative plants up to 96% (control 41%). Estrogens at the same concentration decreased the number of generative plants and 24-epibrassinolide did not stimulate A. thaliana generative development.