Abstract
Anthocyanins are important pigments for flower color, determining the ornamental and economic values of horticultural plants. As a key enzyme in the biosynthesis of anthocyanidins, dihydroflavonol 4-reductase (DFR) catalyzes the reduction of dihydroflavonols to generate the precursors for anthocyanidins (i.e., leucoanthocyanidins) and anthocyanins. To investigate the functions of DFRs in plants, we cloned the GlaDFR1 and GlaDFR2 genes from the petals of Gentiana lutea var. aurantiaca and transformed both genes into Nicotiana tabacum by Agrobacterium-mediated leaf disc method. We further investigated the molecular and phenotypic characteristics of T1 generation transgenic tobacco plants selected based on the hygromycin resistance and verified by both PCR and semiquantitative real-time PCR analyses. The phenotypic segregation was observed in the flower color of the transgenic tobacco plants, showing petals darker than those in the wild-type (WT) plants. Results of high-performance liquid chromatography (HPLC) analysis showed that the contents of gentiocyanin derivatives were decreased in the petals of transgenic plants in comparison to those of WT plants. Ours results revealed the molecular functions of GlaDFR1 and GlaDFR2 in the formation of coloration, providing solid theoretical foundation and candidate genes for further genetic improvement in flower color of plants.
Highlights
The existence of natural pigments generates the colorful world of higher plants [1]
1,200 bp 1,000 bp bp (b) natural conditions. These results suggested that the overexpression of GlaDFR1 and GlaDFR2 in transgenic tobacco plants enhanced the accumulation of pelargonidin in petals
Based on the Agrobacterium-mediated tobacco leaf disc genetic transformation, the gene overexpression vectors pCAMBIA1302GlaDFR1 and pCAMBIA1302-GlaDFR2 were transferred into tobacco genome to generate the transgenic tobacco plants with overexpression of GlaDFR1 and GlaDFR2
Summary
The existence of natural pigments generates the colorful world of higher plants [1]. The roots, stems, leaves, flowers, fruits, and seed coats of different plants contain different types and contents of pigments, giving rise to different colors. The anthocyanidins belonging to flavonoids exist in the form of anthocyanins, which are the glycoside derivatives. More than 550 types of anthocyanidins have been identified and categorized into at least 27 categories, while the common anthocyanidins in plants are mainly revealed in 6 categories, including pelargonidin, malvidin, cyanidin, peonidin, delphinidin, and petunidin [12,13,14,15]. These anthocyanidins are differentiated by the methylation and hydroxylation at the R1 and R2 positions of the flavonoid skeleton
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