2019 ASHS Annual Conference

Every holiday season, consumers are attracted to the eye-catching bracts of poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch), the most popular holiday potted plant. Anthocyanin pigments produce the red and pink colors of poinsettia bracts. Pigment profiles of modern poinsettia cultivars are lacking as identification and measurement of anthocyanins in poinsettia cultivars has not been conducted since the 1980’s. High Performance Liquid Chromatography (HPLC) is the standard method for anthocyanin identification and quantification. Methods for extracting and analyzing anthocyanins in pitanga fruit using HPLC were adapted for poinsettia bracts. Pigments were extracted using an acidic methanol solution, separated from other flavonoids using a C18 porous matrix cartridge (Waters^TM), then separated from sugars using acid hydrolysis. HPLC analysis was conducted using a Waters^TM Alliance 2695 Separations Module with a Waters^TM 996 Photodiode Array Detector. Separation of anthocyanidins was accomplished with an XBridge^TM Peptide XB-C18 column. Separating the sugars leaves the anthocyanidin aglycones, simplifying identification and allowing for accurate quantification of total anthocyanin content using external standards. This protocol produced rapid and optimal HPLC chromatograms with high peak symmetry and excellent baseline resolution. Identification and quantification of the anthocyanidins and total anthocyanin content in a range of colors of modern poinsettia cultivars was performed using this protocol. Cyanidins occur in the greatest concentration, followed by pelargonidins. Total anthocyanin content was highest in red cultivars, followed by pink cultivars. White cultivars contained the least amounts of anthocyanins. Anthocyanin profiles of modern commercial poinsettia cultivars will be useful to poinsettia breeders tasked with creating new and improved cultivars for the industry. Characterization of current germplasm and new hybrids will help breeders make hybridization decisions and evaluate commercial viability of new hybrids.