Genetic engineering of novel yellow color african violet (Saintpaulia ionantha) produced by accumulation of Aureusidin 6-O-glucoside

Abstract

Background Flower color is one of the main characteristics of ornamental plants. Aurones are light yellow flavonoids produced in the petals of a limited number of plant species including snapdragon (Antirrhinum majus). As a commercially-recognized species, African violet can be found in various colors except yellow. This research, aiming at changing the petals’ color of African violet from white to yellow, was conducted using the simultaneous expressions of chalcone 4’-O-glucosyltransferase (4’CGT) and aureusidin synthase (AS1) genes without the need for silencing anthocyanin biosynthesis pathway genes via both transient and stable transfer methods. Results The transient gene transfer among transgenic plants led to a clear change of petals’ color from white to light yellow. This occurs while no change was observed in non-transgenic (Wild type) petals. In total, 15 positive transgenic plants, produced via stable gene transfer, were detected. Moreover, since their flower color was yellow, both genes were present. Meanwhile, the corresponding transformation yield was determined 20-30%. The transformation, expression and integration of genes among T0 transgenic plants were verified using the PCR, qRT-PCR and Southern blotting techniques, respectively. Furthermore, the probable color change of petals’ cross-section and existence of Aureusidin 6-O-glucoside (AOG) compound were determined using a light microscope and HPLC-DAD-MSn analysis, correspondingly. Conclusions Generally, the creation of aurones biosynthesis pathway is only viable through the simultaneous expression of genes which leads to color change of African violet’s petal from white to yellow. This conclusion can lead to an effective strategy to produce yellow color in ornamental plant species.

Comparative Transcriptome Analysis Unveils the Molecular Mechanism Underlying Sepal Colour Changes under Acidic pH Substratum in Hydrangea macrophylla

“…Anthocyanins are the end products of the biosynthetic pathways of flavonoids. They produce a wide variety of colours, from pale yellow to blue–violet [ 36 ]. The accumulation of the floral anthocyanins malvidin and petunidin causes the colour difference between Al 3+ -treated (blue–violet) and untreated (pink) hydrangea sepals ( Figure 1 ).…”

Biotechnologically Engineered Plants

“…The flowers of the yellow-colored cultivar accumulated aureusidin 6-o-glucoside (AOG), a yellow-pigmented compound. In this case, both genes are required to induce expression of AOG to change the color of African violet flowers from white to yellow [ 157 ].…”

A multifaceted review on aureusidin in planta distribution, (bio)synthesis, and bioactivities

“…This metabolic pathway is unique among the known examples of flavonoids, including anthocyanin biosynthesis as for all other compounds, the carbon backbone is completed prior to transport inside the vacuole (Ono et al., 2006). Nowadays, a combination of the coexpression of AUR synthase and Am4′ CGT has emerged as an effective strategy for generating yellow varieties in horticultural plants (Hoshino et al., 2019; Rajabi et al., 2022). The coexpression of snapdragon ( A. majus ) chalcone 4′‐O‐glucosyltransferase (Am4′CGT) and AUS ( AmAs1 ) genes in tobacco and lettuce leaves developed a yellow hue accompanied with higher superoxide dismutase inhibiting and (ORAC) activities suggesting that the nutritional qualities of leafy vegetables can be improved by expressing aurone biosynthetic pathways (Shakya et al., 2012).…”