Identification and Functional Analysis of a Flavonol Synthase Gene from Grape Hyacinth.

Hongli Liu,Jiaxin Gong,Lingjuan Du,Han Zhang,Yali Liu,Beibei Su,Boxiao Zhang

doi:10.3390/molecules24081579

Hongli Liu, Jiaxin Gong + Show 5 more

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https://doi.org/10.3390/molecules24081579

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Abstract

Flavonols are important copigments that affect flower petal coloration. Flavonol synthase (FLS) catalyzes the conversion of dihydroflavonols to flavonols. In this study, we identified a FLS gene, MaFLS, expressed in petals of the ornamental monocot Muscari aucheri (grape hyacinth) and analyzed its spatial and temporal expression patterns. qRT-PCR analysis showed that MaFLS was predominantly expressed in the early stages of flower development. We next analyzed the in planta functions of MaFLS. Heterologous expression of MaFLS in Nicotiana tabacum (tobacco) resulted in a reduction in pigmentation in the petals, substantially inhibiting the expression of endogenous tobacco genes involved in anthocyanin biosynthesis (i.e., NtDFR, NtANS, and NtAN2) and upregulating the expression of NtFLS. The total anthocyanin content in the petals of the transformed tobacco plants was dramatically reduced, whereas the total flavonol content was increased. Our study suggests that MaFLS plays a key role in flavonol biosynthesis and flower coloration in grape hyacinth. Moreover, MaFLS may represent a new potential gene for molecular breeding of flower color modification and provide a basis for analyzing the effects of copigmentation on flower coloration in grape hyacinth.

Highlights

Flower color is a key characteristic of ornamental plants [1]
We identified a flavonol synthase (FLS) gene expressed in grape hyacinth petals, MaFLS, and analyzed its spatial and temporal expression patterns
The color of the extractions indicated that the petals of lines with a severe phenotype contained less anthocyanins than the nonhigher levels of total flavonols, compared to the non-transformed control (Figure 5C). These results strongly suggest that high-level MaFLS expression in transgenic tobacco lines causes a remarkable decrease in anthocyanin content and an increase in flavonol accumulation in vivo, which results in a severe reduction in petal pigmentation

Summary

Introduction

Flower color is a key characteristic of ornamental plants [1]. Anthocyanins are flavonoids that contribute to the pink, red, orange, scarlet, violet, blue, and yellow pigmentation of ornamental plant flowers [2]. Copigmentation with other flavonoids influences the hue and intensity of flower color. Copigmentation can stabilize colored pigments and induce a blue shift in the final visible color [3]. Flavonols are one group of flavonoid that can act as copigments sandwiched between anthocyanins, causing color shifts and an increased color variety [1]. Flavonols can themselves impart pale yellow or yellow coloration [4]

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