# Telomere-to-telomere genome assembly and multiomics analyses illustrate the high accumulation of quercetin glucosides in tetraploid Descurainia sophia

## TL;DR

This study identifies the genetic basis for high quercetin glucoside accumulation in tetraploid Descurainia sophia and explains the origin of its diploid relative's genome.

## Contribution

The study reveals how gene duplication and evolution of a UGT gene leads to high quercetin glucoside levels in tetraploid D. sophia.

## Key findings

- Gene duplication and functional evolution of Dscd6AG01520 UGT gene causes high quercetin glucoside accumulation in tetraploid D. sophia.
- Amino acid S213 in Dscd6AG01520 is critical for enzymatic activity.
- Diploid D. sophia evolved from an ancestral crucifer karyotype through chromosome fusion and rearrangement.

## Abstract

Quercetin glucosides are important phytopharmaceutical metabolites in Descurainia sophia seeds, which are widely used in traditional herbal medicine. However, the key genes involved in quercetin glucoside biosynthesis in D. sophia have not been characterized. Herein, we present the telomere-to-telomere genomes of a tetraploid D. sophia, which accumulates high levels of quercetin glucoside, and a diploid D. sophia, which accumulates only trace amounts. Multiomics analyses and uridine diphosphate glucosyltransferase (UGT) enzyme assays revealed that the gene duplication and functional evolution of Dscd6AG01520, an UGT gene, led to high quercetin-3-O-β-d-glucoside and quercetin-3,7-O-β-d-diglucoside accumulation in tetraploid D. sophia seeds. Further UGT enzyme assays with the point mutations of Dscd6AG01520 showed that S213 was a critical amino acid for the enzymatic activity of Dscd6AG01520. In addition, we found that diploid D. sophia evolved from an ancestral crucifer karyotype through chromosome fusion and rearrangement. Collectively, our findings illuminate the mechanism of high quercetin glucoside accumulation in tetraploid D. sophia, clarify the origin of the diploid D. sophia genome, and provide valuable genomic resources for comparative genomics and research into polyploid evolution.