Genetic analysis of anthocyan biosynthesis in Poinsettia (Euphorbia pulcherrima WILLD. Ex. KLOTZSCH)

The major ornamental characteristic of Poinsettias is a group of conspicuous bracts that display shades of red to pink but comprise also cream and white forms. Previous biochemical and  genetic analyses indicate that only a single or a few loci are responsible for the difference between white and red genotypes and that the biochemical block is most likely at or near the function of the anthocyanin synthase (ANS). To investigate the genetic basis of these colour changes we performed next generation sequencing of the bract transcriptomes of white and red genotypes. We obtained 35000 and 51000 contigs for the red and white genotypes respectively among which 4000 were unique to the red genotypes. We found two orthologues of the ANS gene but as both are expressed in white and in red genotypes we can exclude simple transcriptional regulation of ANS function. We are in the process of functional characterization of different alleles of both ANS paralogues and analyse both expression and gene structure of additional candidate genes downstream of the ANS function.