# Qu-1: a transformation-and regeneration-amenable doubled haploid cell line with a reference genome sequence for genetic and functional studies in Populus

## TL;DR

Researchers created a poplar cell line with a complete genome, useful for studying genetics and biology in woody plants.

## Contribution

The first poplar cell line with a homozygous genome and efficient transformation methods for genetic studies.

## Key findings

- Qu-1 is a doubled haploid cell line with high viability and plant regeneration ability.
- A chromosome-level genome assembly was achieved using PacBio sequencing.
- Efficient transient and stable transformation systems were developed for Qu-1.

## Abstract

Plant suspension homogeneous cells are invaluable materials for investigating molecular mechanisms underlying various biological processes. In this study, we established and characterized a doubled haploid cell line from Populus
simonii × P.
nigra, designated as Qu-1. This cell line exhibited high viability and dispersibility under suspension culture conditions and retained the ability to regenerate into whole plants. K-mer analysis confirmed the homozygous genome of Qu-1, and a chromosome-level genome assembly was subsequently achieved by using PacBio sequencing. Additionally, we established an efficient transient transformation protocol using PEG-mediated protoplasts and a stable Agrobacterium-mediated transformation system for Qu-1. To explore the mutagenesis potential of this cell line, we treated the cell line with ethyl methanesulfonate (EMS) and performed genome resequencing to identify mutation sites. Overall, Qu-1 represents the first poplar cell line with a homozygous genome and is as a powerful tool for molecular biology research in woody plants.