Chromosome-level genome assemblies of sunflower oilseed and confectionery cultivars
In this study, we obtained high-quality genomes of two cultivar representatives of oil and confectionery common sunflower (Helianthus annuus L.) lineages in China at the chromosome level using the PacBio Revio system Circular Consensus Sequencing and high-throughput chromatin conformation capture (Hi-C) scaffolding sequencing technologies. OXS is an inbred oil-type sunflower line with high kernel rate (74.5% kernels), contains 42.9% oil and fat. It is highly susceptible to Verticillium wilt and moderately susceptible to several other diseases. YDS is an inbred non-oil line with high plant height (180-220 cm) and large plump seeds (19.23 grams per 100 seeds). The genome assembly of OXS, spans 3.03 Gb, with 99.58% of sequences anchored to 17 chromosomes and a contig N50 length of 154 Mb. Similarly, the assembly size of YDS, is 3.02 Gb, with 99.40% of sequences mapped to 17 chromosomes and a contig N50 length of 153 Mb. The gene completeness of BUSCO reached 98.2% for OXS and 98.4% for YDS, while the LTR Assembly Index (LAI) stood at 24.73 and 25.85 for OXS and YDS, respectively. A comparative genomics approach identified 6,535 (OXS) and 6,498 (YDS) gene families that have evolved rapidly and are associated with substance synthesis, cell growth, grain weight, and protective mechanisms against biotic and abiotic stresses. We discovered that the YDS genome assembly shows high collinearity with the OXS assembly, apart from three significant inversions on chromosomes 7 and 17. We also identified 15,056 large deletions and insertions between the OXS and YDS assemblies. The publication of these genomes has greatly contributed to the improvement of genetic breeding by integrating internal genetic and external environmental factors in Helianthus annuus L. crops.