Project description:ObjectiveBorassus flabellifer or Asian Palmyra palm is widely distributed in South and Southeast Asia and is horticultural and economic importance for its fruit and palm sugar production. However, its population is in rapid decline, and only a few genetic data are available. We sequenced the complete chloroplast (cp) genome of B. flabellifer to provide its genetic data for further utilization.ResultsThe cp genome was obtained by Illumina sequencing and manual gap fillings providing 160,021 bp in length containing a pair of inverted repeats (IRs) with 27,256 bp. These IRs divide the genome into a large single copy region 87,444 bp and a small single copy region 18,065 bp. In total, 113 unique genes, 134 SSRs and 47 large repeats were identified. This is the first complete cp genome reported in the genus Borassus. A comparative analysis among members of the Borasseae tribe revealed that the B. flabellifer cp genome is, so far, the largest and the cp genomes of this tribe have a similar structure, gene number and gene arrangement. A phylogenetic tree reconstructed based on 74 protein-coding genes from 70 monocots demonstrates short branch lengths indicating slow evolutionary rates of cp genomes in family Arecaceae.
Project description:We have identified 46 RNA editing sites located in 20 chloroplast (cp) genes of Borassus flabellifer (Asian Palmyra palm), family Arecaceae, and tested these genes for supporting phylogenetic study among the commelinids. Among the 46 sites, 43 sites were found to cause amino acid alterations, which were predicted to increase the hydrophobicity and transmembrane regions of the proteins, and one site was to cause a premature stop codon. Analysis of these editing sites with data obtained from seed plants showed that a number of shared-editing sites depend on the evolutionary relationship between plants. We reconstructed a deep phylogenetic relationship among the commelinids using seven RNA edited genes that are orthologous among monocots. This tree could represent the relationship among subfamilies of Arecaceae family, but was insufficient to represent the relationship among the orders of the commelinid. After adding eight gene sequences with high parsimony-informative characters (PICs), the tree topology was improved and could support the topology for the commelinid orders ((Arecales,Dasypogenaceae) (Zingiberales+Commelinales,Poales)). The result provides support for inherent RNA editing along the evolution of seed plants, and we provide an alternative set of loci for the phylogenetic tree reconstruction of Arecaceae's subfamilies.
