Abstract
The onion (Allium cepa L.) flavonol synthase (AcFLS-HRB) gene, encoding an enzyme responsible for flavonol biosynthesis in yellow onion, was recently identified and enzymatically characterized. Here, we performed an in vivo feeding assay involving bacterial expression of AcFLS-HRB and observed that it exhibited both flavanone 3-hydroxylase (F3H) and FLS activity. Transgenic tobacco (Nicotiana tabacum) expressing AcFLS-HRB produced lighter-pink flowers compared to wild-type plants. In transgenic petals, AcFLS-HRB was highly expressed at the mRNA and protein levels, and most AcFLS-HRB protein accumulated in the insoluble microsomal fractions. High-performance liquid chromatography (HPLC) analysis showed that flavonol levels increased but anthocyanin levels decreased in transgenic petals, indicating that AcFLS-HRB is a functional gene in planta. Gene expression analysis showed the reduced transcript levels of general phenylpropanoid biosynthetic genes and flavonoid biosynthetic genes in AcFLS-HRB overexpressed tobacco petals. Additionally, transgenic tobacco plants at the seedling stages showed increased primary root and root hair length and enhanced quercetin signals in roots. Exogenous supplementation with quercetin 3-O-rutinoside (rutin) led to the same phenotypic changes in root growth, suggesting that rutin is the causal compound that promotes root growth in tobacco. Therefore, augmenting flavonol levels affects both flower color and root growth in tobacco.
Highlights
Flavonoids, one of the largest groups of plant secondary metabolites, are involved in plant growth, development, reproduction, and responses to biotic and abiotic stress [1]
These results indicate that the functional expression of AcFLS-HRB in tobacco caused an increase in flavonol accumulation and a decrease in anthocyanin accumulation in the transgenic petals, resulting in light pink and pale pink flowers
An in vivo substrate-feeding assay showed that flavanones could be converted to dihydroflavonols activity
Summary
Flavonoids, one of the largest groups of plant secondary metabolites, are involved in plant growth, development, reproduction, and responses to biotic and abiotic stress [1]. F3H and significantly reduced flavonol levels, has shorter primary roots than the wild-type [37] These findings indicate that the patterns of flavonol-mediated root growth differ depending on the plant species, since root phenotypes result from the integrated signaling of PAT, ROS, and flavonol. Transgenic tobacco produced lighter-pink flowers containing higher flavonol levels and lower anthocyanin levels than the wild-type In accordance with these phenotypes, phenylpropanoid biosynthesis genes and several flavonoid. In accordance with these phenotypes, phenylpropanoid biosynthesis genes and several flavonoid biosynthetic genes were down-regulated transgenic petals. These findings indicate that quercetin quercetin levels promote growth ingrowth tobacco.in tobacco
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
