In vitro shoot regeneration is implemented in basic plant research and commercial plant production, but for some plant species, it is still difficult to achieve by means of the currently available cytokinins and auxins. To identify novel compounds that promote shoot regeneration, we screened a library of 10,000 small molecules. The bioassay consisted of a two-step regeneration protocol adjusted and optimized for high-throughput manipulations of root explants of Arabidopsis (Arabidopsis thaliana) carrying the shoot regeneration marker LIGHT-DEPENDENT SHORT HYPOCOTYLS4. The screen revealed a single compound, the cytokinin-like phenyl-adenine (Phe-Ade), as a potent inducer of adventitious shoots. [read more]