Functional role of DFR genes in various blue Iris for the regulation of delphinidin synthesis.

Flowers belonging to the Iris genus, with a predominant display of blue hues, showcase a variety of blue polymorphisms across different species. This study focused on analyzing the L∗, a∗, and b∗ color values of Iris typhifolia, I. lactea, I. laevigata, and I. sanguinea. Notably, I. lactea exhibited the highest L∗ value, indicating a brighter hue, while I. typhifolia and I. laevigata displayed larger a∗ values, suggesting a shift towards a reddish tone. I. sanguinea, conversely, presented the most profound blue with the lowest b∗ value. Our research delved into understanding the influence of anthocyanin components on these color variations and explored the regulatory role of the dihydroflavonol-4-reductase (DFR) gene. The findings underscore delphinidin as the primary blue pigment, with the additional presence of petunidin in I. typhifolia and I. laevigata introducing a purplish-red hue. Flavonoids were identified as contributors to enhancing the brightness of I. lactea's color. The study elucidates that blue polymorphism predominantly arises from varying proportions of delphinidin pigments, closely linked to substrate selection by Asp type DFRs. Following the expression of different DFR genes from the two blue Iris species, significant substrate selection differences were observed. These findings lay a foundation for future efforts to enhance flower colors in Irises and other related species by offering DFR as a target candidate gene.