I wonder if Robert Burns would have felt as inspired about blue roses as he was about the romantic red. Personally speaking, I prefer my geraniums red and delphiniums blue although I find the desire for horticultural oddities quite fascinating. For many centuries a true blue flower has been the Holy Grail of plant breeders with many attempts resulting in lilac or merely ‘bluish’ flowers.
Florists, many of which currently dye their roses blue, anxiously await the release of ‘The World’s First Blue Rose‘, a GM flower created by a combination of gene silencing and introduction of delphinidin genes*. Although only pale violet in colour this rose is still a world first as it’s colour does actually come from delphinidin rather than from modification of other anthocyanins.
However, a recently published paper on tulips may help unravel the mystery of blue colouration. Unlike carnations and roses, some tulips do actually contain delphinidin. In one particular tulip, Tulipa gesneriana cv. Murasakizuisho, the main part of the petal is purple whilst the bottom of the petal is blue. Although both the purple and blue parts of the petal appeared to be chemically similar with regard to anthocyanin and flavonol composition it was found that the ferric ion content of the blue sample was 25 times higher than that of the purple, from these results Shoji et al. conclude that ferric ions are essential for blue colour development in tulips.
So the dream of a true blue flower may be closer to reality, but maybe not in time for this Mother’s Day!
The paper Perianth Bottom-Specific Blue Colour Development in Tulip cv. Murasakizuisho Requires Ferric Ions by Shoji et al. is published in Plant Cell Physiol. 48(2):243-251.
*Information sheet on blue roses using technology developed by CSIRO, Australia.
For more on blue roses and advances in horticulture please visit CAB Direct.