HORT1 retrotransposon causes harlequin/black flowers in Phalaenopsis orchids (Plant Physiol)

Phalaenopsis orchids produce beautiful, long-lived flowers and are widely popular houseplants. In 1996, a new variety was identified with intensely dark, nearly black pigmentation. Hsu et al. have identified the molecular basis for this phenotype; a Gypsy-like retrotransposon inserted in the promoter of a gene encoding a MYB transcription factor. Insertion of HORT1 (Harlequin Orchid RetroTransposon1) leads to a highly variable pigmentation pattern as well as high levels of anthocyanin production throughout the petal’s central cell layers, giving the petals a black appearance. (Summary by Mary Williams)  Plant Physiol. 10.1104/pp.19.00205