Flowering Blues

Today I was weeding a bed of roses, and pulled out many handsful of Veronica persica Poiret. The flowers are small, but a beautiful shade of blue that comes from an excessively complex form of delphinidin [delphinidin 3-O-(2-O-(6-O-p-coumaroyl-glucosyl)-6-O-p-coumaroyl-glucoside)-5-O-glucoside] and a complex form of apigenin [apigenin 7-O-(2-O-glucuronosyl)-glucuronide]. Such complexity for a tiny flower!
https://www.ncbi.nlm.nih.gov/pubmed/20223486

In the summer I expect to find another of my favorite weeds, Commelina communis L. This also relies on a very complex pigment called commelinin, which is composed of Malonylawobanin [delphinidin 3-O-(6-O-p-coumaroylglucoside)-5-O-(6-O-malonylglucoside)] and Flavocommelin [swertisin 4-O-glucoside].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3720548/figure/f1-452/

Even the blue delphinium relies on a complex delphinidin derivative called violdelphin: delphinidin 3-rutinoside-7-O-(6-O-(4-(6-O-(4-hydroxybenzoyl)-beta-D-glucosyl)oxybenzoyl)-beta-D-glucoside).
https://pubchem.ncbi.nlm.nih.gov/compound/3083066#section=Top

Delphinin has already been added to roses, with results that are less than dazzling. It might take a while to get from introduced delphinidin to a genuine blue.

The Heavenly Blue morning glory flowers are colored by peonidin 3-(dicaffeylsophoroside)-5-glucoside in a highly alkaline solution.
https://www.sciencedirect.com/science/article/abs/pii/S0031942200867679

Roses already produce cyanidin 3-sophoroside, which suggests that a peonidin 3-sophoroside would be possible by breeding rather than by gene transplanting. [e.g., by crossing the peonin-rich 'Hansa' with Rosa rugosa 'Salmon Pink', which is colored by cyanidin 3-sophoroside.]

And the existence in roses of peonidin 3-ρ-coumaroylglucoside-5-glucoside, suggests the possibility of getting to peonidin 3-ρ-coumaroylsophoroside, though without the 5-glucoside part because in roses the 5 position is populated before the 3 in the 3,5 diglucosides. I don't know that the addition of one molecule of ρ-coumaric acid would have the same effect as two caffeic acid molecules, but it's worth investigating.
Mikanagi (2000)