Schizanthus grahamii and Schizanthus hookeri. Is there any relationship between their anthocyanin compositions and their different pollination syndromes?

The anthocyanin compositions of Schizanthus grahamii and Schizanthus hookeri flowers are qualitatively and quantitatively different, thus contributing to the different pollination syndromes that they show. [Display omitted] ► Total anthocyanin content is much higher in Schizanthus grahamii than in Schizanthus hookeri. ► Delphinidin 3-O-glucoside is the major anthocyanin in S. grahamii red flowers (hummingbird). ► Petanin is the major anthocyanin in S. hookeri bluish-pink flowers (bee). ► Common pigments in both species can be indicative of a common ancestor. ► Synthesis of simpler red pigments by S. grahamii is related to specialisation. Three different pollination syndromes (bee, hummingbird and moth-pollination syndromes) have been described for the different species of the genus Schizanthus Ruiz & Pav. (Solanaceae). Two closely related species from a phylogenetic point of view, Schizanthus grahamii and Schizanthus hookeri, show hummingbird and bee-pollination syndromes, respectively. One of the traits used to assign these pollination syndromes is the colour of the petals, which is red in S. grahamii and bluish-pink in S. hookeri. The objective of this work was to establish the differences in the anthocyanin composition of these two Schizanthus species that contribute to the different pollination syndrome. Identification of the pigments was carried out from the chromatographic and spectral data supplied by the HPLC-DAD-MSn analyses of the samples. Alkaline and acid hydrolyses were also performed in the extracts and in some isolated compounds in order to confirm the identities. First difference between these two species was found in the total anthocyanin content, which was about 13-fold higher in S. grahamii than in S. hookeri. Furthermore, the major peak was also different in both cases, thus explaining quantitative and qualitative colour differences between species. Delphinidin 3-O-rutinoside represented ca. 72% of the total area in S. grahamii and petanin (Petunidin 3-O-p-coumaroylrutinoside-5-O-glucoside) accounted for almost 62% of the total area in S. hookeri. The presence of the p-coumaroylrutinosyl moiety in the petanin makes the intramolecular copigmentation possible, thus conferring the bluish-pink hue to the petals of S. hookeri. Delphinidin 3-O-rutinoside is in turn responsible for the red colour exhibited by the petals of S. grahamii and along with other floral traits, responsible for the attraction of hummingbirds to the plant. Pigments stru