Understanding the control of anthocyanin biosynthesis is beneficial to genetic improvement for floral production in Dendrobium orchids. Full-length cDNA of CHS, CHI1, CHI2, F3H, DFR, ANS, F3'5'H, and FLS was isolated from Dendrobium hybrids with purple, peach, white and greenish white flowers. Analysis of the deduced amino acid sequences and gene expression levels of the eight genes suggested potential causes of color variation among the hybrids. Peach hybrid (SC) was likely due to changes in anthocyanin production from cyanidin to pelargonidin through mutations in F3'H, and the low color intensity was likely derived from the low expression levels of CHI1 and CHI2. In addition, white hybrid (RW) was likely caused by several mutations in F3H and/or high expression levels of FLS, an enzyme that converts color flavonoid intermediates into colorless flavonols. Simultaneous loss of F3H, DFR, and ANS expression observed in another white hybrid (JW) indicated that an alteration of anthocyanin regulatory controls was likely the cause of white coloration. Furthermore, analysis of hybrid mutants bearing pale and dark flowers demonstrated the influence of the expression of anthocyanin genes on the intensity of flower colors. Data obtained from this work could contribute to new strategies for future orchid breeding.

Objective Borassus 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.Electronic supplementary materialThe online version of this article (10.1186/s13104-017-3077-8) contains supplementary material, which is available to authorized users.

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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) (Zingi-berales+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.