Brassinolide promotes adventitious shoot regeneration from cauliflower hypocotyl segments

When hypocotyl segments of cauliflower (Brassica oleracea var. boturytis L.) were cultured on MS medium containing brassinolide (BR) in the light, a significant stimulation of adventitious shoot regeneration was observed. Cytokinins (zeatin and iso-pentenylaminopurine) also promoted shoot regeneration. When BR was added together with these cytokinins, the maximal regeneration was strongly improved and the dose–response curve of cytokinin was shifted to the left. Regeneration was much lower in the dark. This was not due to a possible increased ethylene synthesis in the dark.