Investigations of phytochrome mutants of Arabidopsis suggested that the expression of chalcone synthase (chs) and anthocyanin accumulation is predominantly controlled by phytochrome A. To test the functionality of phytochrome A and B at the molecular level recombinant, yeast-derived phytochrome-phycocyanobilin adducts (phyA, phyB) and oat phytochrome A (phyA) were microinjected into etiolated aurea tomato seedlings. Subsequent to microinjection anthocyanin and chlorophyll accumulation was monitored as well as beta-glucuronidase (GUS) expression mediated by light-regulated promoters (chs, chlorophyll a/b binding protein (lhcb1) and ferredoxin NADP+ oxidoreductase (fnn). Microinjection of phyA under white light conditions caused anthocyanin and chlorophyll accumulation and mediated chs-GUS, lhcb 1-GUS and fnr-GUS expression. Microinjection of phyB under identical conditions induced chlorophyll accumulation and mediated lhcb 1-GUS and fnr-GUS expression but neither anthocyanin accumulation nor chs-GUS expression were observed. The characterization of Arabidopsis phytochrome mutants and the microinjection experiments suggested that phyB cannot induce the accumulation of juvenile anthocyanin. Microinjections under far-red light conditions demonstrated that phyA can act independently of other photoreceptors. By contrast, phyB injections under red light conditions indicated that phyB needs interactions with other photoreceptors to mediate a rapid and efficient de-etiolation signal.