The Chloroplast Genome Sequence of Date Palm (Phoenix dactylifera L. cv. 'Aseel')

Date palm (Phoenix dactylifera L.) is an economically important and widely cultivated palm of the family Arecaceae. We sequenced the complete date palm chloroplast genome (cpDNA) from Pakistani cv. 'Aseel', using a combination of Sanger-based and next-generation sequencing technologies. Being very similar to a sequence from a Saudi Arabian date palm cultivar 'Khalas' published recently, the size of the genome was 158,458 bp with a pair of inverted repeat (IR) regions of 27,276 bp that were separated by a large single-copy (LSC) region of 86,195 bp and a small single-copy (SSC) region of 17,711 bp. Genome annotation demonstrated a total of 138 genes, of which 89 were protein coding, 39 were tRNA, and eight were rRNA genes. Comparison of cpDNA sequences of cultivars 'Aseel' and 'Khalas' showed following intervarietal variations in the LSC region; (a) two SNPs in intergenic spacers and one SNP in the rpoc1 gene, (b) polymorphism in two mono-nucleotide simple sequence repeats (SSR), and (c) a 4-bp indel in the accD-psaI intergenic spacer. The SSC region has a polymorphic site in the mono-nucleotide SSR located at position 120,710. We also compared cv. 'Aseel' cpDNA sequence with partial P. dactylifera cpDNA sequence entries deposited in Genbank and identified a number of potentially useful polymorphisms in this species. Analysis of date palm cpDNA sequences revealed a close relationship with Typha latifolia. Occurrence of small numbers of forward and inverted repeats in date palm cpDNA indicated conserved genome arrangement.