The colour variations of flowers in wild Paeonia delavayi plants are determined by four classes of plant pigments

Paeonia delavayi is listed as an endangered species in the southwest of China. The flower colours of cultivated examples of this species are most commonly yellow and red, but a much wider range of flower colours can be found in plants growing in the natural habitat. To elucidate the basis of the colour range, pigments were extracted from flower petals of seven selected colours and profiled and quantified using High Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry (LC-MS). All the petal colours were found to share the same base pigment types as the yellow flower – a composite colour based on a mix of flavonoids, carotenoids and chlorophyll. Anthocyanin profiling revealed the same anthocyanin compositions in all red coloured flowers, namely, cyanidin-3,5-diglucoside, cyanidin-3-glucoside, cyanidin-3-arabinoside, peonidin-3,5-diglucoside, peonidin-3-glucoside and peonidin 3-arabinoside. Quantitative analysis suggested the yellow colour was principally formed by the flavonoid naringenin chalcone 2'-glucoside (2',4',6',4-tetrahydroxychalcone 2'-glucoside). The various red/orange flower colours were the result of superimposing different amounts of anthocyanins onto the yellow flower background, with carotenoids and chlorophylls having only a minor contribution to the final colour. The results provide useful information for breeding programmes for ornamental varieties of P. delavayi.