An R2R3-MYB transcription factor ODORANT1 regulates fragrance biosynthesis in lilies (Lilium spp.)

Abstract

Flower fragrance is an important character for economic and ecological reasons. Lilies (Lilium spp.), important ornamental crops, mainly emit benzenoids/phenylpropanoids and terpenoids. Oriental hybrid lilies emit a strong fragrance, while Asiatic hybrid lilies often emit a weak fragrance. To delineate the genetic backgrounds that regulate volatile benzenoid/phenylpropanoid production in lilies, we isolated an R2R3-MYB transcription factor similar to Petunia × hybrida ODORANT1 (ODO1) from Oriental and Asiatic hybrid lilies. An identified gene, named Lilium hybrid ODO1 (LhODO1), could upregulate the expression of shikimate pathway genes and phenylalanine ammonia lyase (PAL) genes in transgenic petunia plants. The expression of LhODO1 in the Oriental hybrid lily ‘Casa Blanca’ exhibited a diurnal rhythm, which was highest at 16:00 and lowest at 4:00, and was attuned to the expressional rhythms of shikimate pathway and PAL genes. These diurnal changes in gene expression preceded changes in the production of endogenous volatile compounds. Expression of LhODO1 was specific to tepals, which are major sources of floral scent, and began at anthesis. These results indicate that LhODO1 plays a key role in the regulation of volatile benzenoid/phenylpropanoid production in lilies. In addition, LhODO1 may be responsible for the different fragrance intensities observed between the Oriental and Asiatic hybrid lilies, because LhODO1 expression was high in the Oriental hybrid lily cultivars but very low in wild lilies in sections Sinomartagon and Daurolirion, which are parental species of Asiatic hybrid lilies.