主要研究：We report a highly contiguous genome assembly of an oleiferous type of B. juncea variety Varuna, an archetypical Indian gene pool line of mustard, with ~100x PacBio single‐molecule real‐time (SMRT) long‐reads providing contigs with an N50 value of >5Mb.

结果1-进一步组装：Contigs were corrected for the misassemblies and scaffolded with BioNano optical mapping.

结果2-黑芥基因组：We also assembled a draft genome of B. nigra (BB) variety Sangam using Illumina short‐read sequencing and Oxford Nanopore long‐reads and used it to validate the assembly of the B genome of B. juncea.

结果3-染色体组装：Two different linkage maps of B. juncea, containing a large number of genotyping‐by‐sequencing markers were developed and used to anchor scaffolds/contigs to the 18 linkage groups of the species. The resulting chromosome‐scale assembly of B. juncea Varuna is a significant improvement over the previous draft assembly of B. juncea Tumida, a vegetable type of mustard.

结果4-基因组特征：The assembled genome was characterized for transposons, centromeric repeats, gene content, and gene block associations. In comparison to the A genome, the B genome contains a significantly higher content of LTR/Gypsy retrotransposons, distinct centromeric repeats, and a large number of B. nigra specific gene clusters that break the gene collinearity between the A and the B genomes.

结论：The B. juncea Varuna assembly will be of major value to the breeding work on oleiferous types of mustard that are grown extensively in south Asia and elsewhere.