Foundational genomic resources for date palm (Phoenix dactylifera): A gap-free, telomere-to-telomere phased assembly of Ajwa and 19 high-quality genome assemblies

Abstract

Phoenix dactylifera L. is an economically, nutritionally, and culturally important fruit crop in the arid and semi-arid regions of the Middle East and North Africa. Here, we present a gap-free, telomere-to-telomere reference genome of the variety Ajwa, along with 19 additional high-quality assemblies (18 female and 1 male). These assemblies reveal updated, corrected chromosome assemblies validated through cytogenetics, Hi-C and optical mapping. Chromosome numbering was revised based on average lengths across all sequenced genomes. The Sex Determination Region (SDR) was inferred on chromosome 14, spanning approximately 15.2 Mb. Nucleolar organizing regions (NORs) were localized on chromosome 10, where a large 45S rDNA locus displayed unique repeat spacer motifs containing transposon-like sequences. In some accessions, a second NOR was identified on the female sex chromosome. This collection of date palm assemblies, anchored by the Ajwa reference genome, provides a fundamental resource for advancing breeding strategies aimed at enhancing the genetic resilience and productivity of date palm.