Activation of anthocyanin synthesis in Cymbidium orchids: variability between known regulators

Cymbidium hybrid 'Jung Frau dos Pueblos' (JDP) is a commercial white flowered orchid cultivar. In this study we investigated whether anthocyanin pigment production could be restored to JDP petals by introducing known anthocyanin-regulating transcription factors through biolistic transformation. Simultaneous transformation of white JDP petals with the maize anthocyanin regulators Leaf color and Colorless1 restored anthocyanin biosynthesis, producing a characteristic biolistic blast pattern of scarlet anthocyanin-producing cells. The effectiveness of different MYB/bHLH combinations to induce anthocyanin pigmentation in JDP petals was assessed, and we demonstrate that the previously uncharacterized R2R3 MYB transcription factor AaMYB1 from Anthurium andraeanum is capable of activating anthocyanin production in Cymbidium petals. The clear distinction between the effectiveness of MYB factors from monocot versus dicot species for inducing anthocyanin pigmentation suggests a specificity of transcription factors between monocots and dicots and that this may be determined by the MYB factor.