A near-complete chromosome-level genome assembly of looseleaf lettuce (Lactuca sativa var. crispa).

Lettuce (Lactuca sativa L., Asteraceae) is one of the most important vegetable crops, known for its various horticultural types and significant morphological variation. The first reference genome of lettuce, a crisphead type (L. sativa var. capitata cv. Salinas), was previously released. Here, we reported a near-complete chromosome-level reference genome for looseleaf lettuce (L. sativa var. crispa). PacBio high-fidelity sequencing, Oxford Nanopore, and Hi-C technologies were employed to produce genome assembly. The final assembly is 2.59 Gb in length with a contig N50 of 205.47 Mb, anchored onto nine chromosomes, containing 14 recognizable telomeres and only 11 gaps. Repetitive sequences account for 77.11% of the genome, and 41,375 protein-coding genes were predicted, with 99.10% of these assigned functional annotations. This chromosome-level genome enriched genomic resources for various horticultural types of lettuce and will facilitate the characterization of morphological variation and genetic improvement in lettuce.