Flower color modification through expression of Aquilegia buergeriana F3′5′H in Petunia hybrida

Aquilegia buergeriana is a native plant in Korea with blue flowers. Flavonoid 3′,5′ hydroxylase (F3′5′H) is a key gene involved in the synthesis of delphinidin pigment responsible for the flower's blue color. We isolated the F3′5′H from the petals of A. buergeriana (AbF3′5′H) and introduced the AbF3′5′H gene into Petunia hybrida using Agrobacterium-mediated transformation. Forty-five plants were acquired from a kanamycin-supplemented medium. Fifteen of these were identified as transgenic plants using polymerase chain reaction (PCR). Quantitative real-time PCR (qRT-PCR) analysis revealed that the AbF3′5′H was expressed in the petal, corolla tube, and stigma of P. hybrida. AbF3′5′H-transgenic plant (T₀) flower color was darker than that of non-transgenic plants (NTs). Particularly, the stigma color was dramatically changed, from light yellow green (145C) to purple (N77C or N79D). The segregation ratio of the three transgenic (T₁) lines was identified as 3:1 by PCR analysis of AbF3′5′H and neomycin phosphotransferase-II. The flower color change of the transgenic lines (T₁) was similar to that of T₀. qRT-PCR analysis showed that AbF3′5′H-transgenic T₁ lines had a higher AbF3′5′H expression than NT in all floral organs. Moreover, delphinidin was confirmed to be accumulated in both corolla tube and stigma and was enhanced in the petals of AbF3′5′H-transgenic T₁ lines through UPLC analysis. Our findings indicate the role of AbF3′5′H in flower color change. These results also indicate the functionality of AbF3′5′H in bluish flower modifications.