# Chromosome-level genome assembly of Helwingia omeiensis: the first genome in the family Helwingiaceae

## TL;DR

This paper presents the first high-quality genome assembly for the plant family Helwingiaceae, offering insights into its unique traits and evolutionary history.

## Contribution

The first chromosome-level genome assembly for the family Helwingiaceae, enabling molecular studies of its unique floral traits.

## Key findings

- The genome of Helwingia omeiensis is assembled at 2.75 Gb with 98.2% BUSCO completeness.
- 53,951 genes were identified and 99.7% were annotated in protein databases.
- The genome provides a foundation for studying the evolution of Helwingiaceae-specific traits.

## Abstract

Helwingia, a shrub of the monotypic cosmopolitan family Helwingiaceae, is distinguished by its inflorescence, in which flowers are borne on the midrib of the leaf—a trait not commonly observed in related plant families. Previous studies have investigated the development of this unusual structure using comparative anatomical methods. However, the scarcity of genomic data has hindered our understanding of the origins and evolutionary history of this uncommon trait at the molecular level. Here, we report the first high-quality genome of the family Helwingiaceae. Assembled using HiFi sequencing and Hi-C technologies, the genome of H. omeiensis is anchored to 19 chromosomes, with a total length of 2.75 Gb and a contig N50 length of 6.78 Mb. The BUSCO completeness score of the assembled genome was 98.2%. 53,951 genes were identified, of which 99.7% were annotated in at least one protein database. The high-quality reference genome of H. omeiensis provides an essential genetic resource and sheds light on the phylogeny and evolution of specific traits in the family Helwingiaceae.