The presence of phytochrome in purified barley etioplasts and its in vitro regulation of biologically-active gibberellin levels in etioplasts.

Data are presented confirming that purified barley etioplasts contain, or have associated with them, consistently detectable amounts of photoreversible phytochrome. Etioplasts, separated from mitochondrial contamination by sucrose gradient centrifugation, respond in vitro to red light treatment by an increase in the level of extractable gibberellin-like substances. It is concluded that earlier reports of the substances. It is concluded that earlier reports of the phytochrome regulation of biologically-active gibberellin levels in crude plastid fractions represent responses of the etioplast alone.