Date palm (Phoenix dactylifera L.) is a cultivated woody plant species with agricultural and economic importance. Here we report a genome assembly for an elite variety (Khalas), which is 605.4 Mb in size and covers >90% of the genome (~671 Mb) and >96% of its genes (~41,660 genes). Genomic sequence analysis demonstrates that P. dactylifera experienced a clear genome-wide duplication after either ancient whole genome duplications or massive segmental duplications. Genetic diversity analysis indicates that its stress resistance and sugar metabolism-related genes tend to be enriched in the chromosomal regions where the density of single-nucleotide polymorphisms is relatively low. Using transcriptomic data, we also illustrate the date palm’s unique sugar metabolism that underlies fruit development and ripening. Our large-scale genomic and transcriptomic data pave the way for further genomic studies not only on P. dactylifera but also other Arecaceae plants.

To compare the two RNA-sequencing protocols, ribo-minus RNA-sequencing (rmRNA-seq) and polyA-selected RNA-sequencing (mRNA-seq), we acquired transcriptomic data-52 and 32 million alignable reads of 35 bases in length-from the mouse cerebrum, respectively. We found that a higher proportion, 44% and 25%, of the uniquely alignable rmRNA-seq reads, is in intergenic and intronic regions, respectively, as compared to 23% and 15% from the mRNA-seq dataset. Further analysis made an additional discovery of transcripts of protein-coding genes (such as Histone, Heg1, and Dux), ncRNAs, snoRNAs, snRNAs, and novel ncRNAs as well as repeat elements in rmRNA-seq dataset. This result suggests that rmRNA-seq method should detect more polyA- or bimorphic transcripts. Finally, through comparative analyses of gene expression profiles among multiple datasets, we demonstrated that different RNA sample preparations may result in significant variations in gene expression profiles.