First draft genome of the decaploid species, Ludwigiagrandiflora subsp. hexapetala, validated through geneexpression

Abstract

Invasive species are one of the biggest drivers of species extinction. Ludwigia grandiflora subsp. hexapetala (Lgh) is widely invasive in aquatic ecosystems of Europe, North America, and Japan, and also colonizes emergent freshwater soils, but limited genomic data constrain studies of its invasiveness. Here, we report a draft genome assembly of Lgh, with a total length of 1.487 Gb, in agreement with the genome size estimated by flow cytometry, despite high fragmentation (111,219 contigs; N50 = 13.5 kb) and low sequencing depth (6.5x Illumina, 1.6x Nanopore). In addition, an analysis combining homology and expression data identified 139,095 protein-coding genes. Moreover, several indicators suggest that the observed fragmentation is largely attributable to unassembled repetitive regions. Thus, despite these limitations, this assembly represents the first genome in the Ludwigioideae subfamily and constitutes a valuable resource for gene discovery, functional genomics, phylogenetic reconstruction, and evolutionary analyses across the Onagraceae family.