infA Gene Research Articles

Comparative analyses of plastomes in Allaeanthus and Malaisia: structure, evolution, and phylogeny.

The small genera Allaeanthus and Malaisia within the Moraceae have important edible, medicinal, and economic value. However, complete plastome blueprints and a well-resolved evolutionary history of these two genera are still lack, thereby limiting their conservation and application. The recent discovery of a new distribution of Allaeanthus kurzii in Hainan, China, marked by the collection of two unique samples, alongside three samples of Malaisia scandens, has opened new avenues for research. This study aimed to compare the Allaeanthus and Malaisia plastomes of Hainan Province samples with those of samples from other regions, focusing on plastome structure, codon usage bias, natural selection, and the evolutionary history of A. kurzii and M. scandens. The results showed that both species had a quadripartite plastome structure, with sizes ranging from 162,134 to 162,170bp for A. kurzii and 161,235 to 162,134bp for M. scandens. Both species displayed loss of the infA gene and reduction of the rpl22 gene. Two highly variable regions (petD-trnD-GUC and rpl20-clpP) and three highly variable genes (rpl20, petB, and rpl16) were identified in A. kurzii, while two highly variable regions (ycf2-ndhB and ccsA-ndhE) and three highly variable genes (psbT, rpl36, and ycf2) were found in M. scandens. The protein-coding sequences (CDSs) of the Allaeanthus and Malaisia plastomes exhibited similar patterns of adaptive indices and codon usage frequencies. The genes associated with photosynthesis underwent strong purifying selection. Phylogenetic analysis revealed that Allaeanthus, Broussonetia, and Malaisia constituted a monophyletic group, with Malaisia being more closely related to Broussonetia. Broussonetia diversified approximately 19.78 million years ago, Malaisia approximately 4.74 million years ago, and Allaeanthus approximately 16.18 million years ago. These new plastome-based discoveries will guide conservation planners and medicinal plant breeders and genetic resource development for these species in the region.

Decoding Evolution of Rubioideae: Plastomes Reveal Sweet Secrets of Codon Usage, Diagnostides, and Superbarcoding.

Galium genus belongs to the Rubiaceae family, which consists of approximately 14,000 species. In comparison to its well-known relatives, the plastomes of the Galium genus have not been explored so far. The plastomes of this genus have a typical, quadripartite structure, but differ in gene content, since the infA gene is missing in Galium palustre and Galium trfidum. An evaluation of the effectiveness of using entire chloroplast genome sequences as superbarcodes for accurate plant species identification revealed the high potential of this method for molecular delimitation within the genus and tribe. The trnE-UUC-psbD region showed the biggest number of diagnostides (diagnostic nucleotides) which might be new potential barcodes, not only in Galium, but also in other closely related genera. Relative synonymous codon usage (RSCU) appeared to be connected with the phylogeny of the Rubiaceae family, showing that during evolution, plants started preferring specific codons over others.

Comparative plastome analysis of the sister genera Ceratocephala and Myosurus (Ranunculaceae) reveals signals of adaptive evolution to arid and aquatic environments

BackgroundExpansion and contraction of inverted repeats can cause considerable variation of plastid genomes (plastomes) in angiosperms. However, little is known about whether structural variations of plastomes are associated with adaptation to or occupancy of new environments. Moreover, adaptive evolution of angiosperm plastid genes remains poorly understood. Here, we sequenced the complete plastomes for four species of xerophytic Ceratocephala and hydrophytic Myosurus, as well as Ficaria verna. By an integration of phylogenomic, comparative genomic, and selection pressure analyses, we investigated evolutionary patterns of plastomes in Ranunculeae and their relationships with adaptation to dry and aquatic habitats.ResultsOwing to the significant contraction of the boundary of IRA/LSC towards the IRA, plastome sizes and IR lengths of Myosurus and Ceratocephala are smaller within Ranunculeae. Compared to other Ranunculeae, the Myosurus plastome lost clpP and rps16, one copy of rpl2 and rpl23, and one intron of rpoC1 and rpl16, and the Ceratocephala plastome added an infA gene and lost one copy of rpl2 and two introns of clpP. A total of 11 plastid genes (14%) showed positive selection, two genes common to Myosurus and Ceratocephala, seven in Ceratocephala only, and two in Myosurus only. Four genes showed strong signals of episodic positive selection. The rps7 gene of Ceratocephala and the rpl32 and ycf4 genes of Myosurus showed an increase in the rate of variation close to 3.3 Ma.ConclusionsThe plastomic structure variations as well as the positive selection of two plastid genes might be related to the colonization of new environments by the common ancestor of Ceratocephala and Myosurus. The seven and two genes under positive selection might be related to the adaptation to dry and aquatic habitats in Ceratocephala and Myosurus, respectively. Moreover, intensified aridity and frequent sea-level fluctuations, as well as global cooling, might have favored an increased rate of change in some genes at about 3.3 Ma, associated with adaptation to dry and aquatic environments, respectively. These findings suggest that changing environments might have influenced structural variations of plastomes and fixed new mutations arising on some plastid genes owing to adaptation to specific habitats.

The complete plastome sequence of Datisca cannabina L. (Datiscaceae, Cucurbitales)

In this study, we report the first complete plastome sequence of Datisca cannabina (GenBank acc. no. OP432690). The plastome had a typical quadripartite structure. Its size was 162,914 bp, consisting of 90,890 bp large single-copy (LSC), 19,296 bp small single-copy (SSC), and 26,364 bp inverted repeat (IR) regions. It contained 112 genes, including 78 protein-coding, 30 tRNA, and four rRNA genes. The infA gene was pseudogenized. Sixteen genes contain one intron and two genes (clpP and ycf3) had two introns. Our phylogenetic tree showed that D. cannabina formed a close relationship with Begoniaceae. However, further samples are required to determine the phylogenetic placement of Datiscaceae in Cucurbitales.

Characterization of the complete plastome sequence of Korean endemic, Cardamine glechomifolia H.Lév. (Brassicaceae, Brassicales)

In this study, we report the complete plastome sequence of Cardamine glechomifolia H.Lév. 1913 (NCBI acc. no. OP894664). This plastome shows typical quadripartite structure. The plastome size is 154,307 bp, which consists of 84,015 bp large single-copy (LSC), 17,690 bp small single-copy (SSC), and 26,301 bp inverted repeat (IR) regions. The plastome contains 112 genes, including 78 protein-coding, 30 tRNA, and four rRNA genes. The infA gene is pseudogenized. Sixteen genes contain one intron and two genes (clpP and ycf3) have two introns. The phylogenomic analysis conducted in our study reveals that the genus Cardamine, which encompasses C. glechomifolia, exhibits three distinct clades. In order to elucidate the interrelationship among the three clades, it is imperative to conduct additional investigations by augmenting the number of Cardamine samples.

Comprehensive Analysis of Chloroplast Genome of Hibiscus sinosyriacus: Evolutionary Studies in Related Species and Genera

The Hibiscus genus of the Malvaceae family is widely distributed and has diverse applications. Hibiscus sinosyriacus is a valuable ornamental tree, but it has not been extensively researched. This study aimed to complete the chloroplast genome of H. sinosyriacus and elucidate its evolutionary relationship with closely related species and genera. The complete chloroplast genome of H. sinosyriacus was found to be 160,892 bp in length, with annotations identifying 130 genes, including 85 coding genes, 37 tRNAs, and 8 rRNAs. Interspecific variations in the Hibiscus spp. were explored, and H. sinosyriacus has species-specific single-nucleotide polymorphisms in four genes. Genome structure analysis and visualization revealed that in the Abelmoschus genus, parts of the large single-copy region, including rps19, rpl22, and rps3, have been incorporated into the inverted repeat region, leading to a duplication and an increase in the number of genes. Furthermore, within the Malvales order, the infA gene remains in some genera. Phylogenetic analysis using the whole genome and coding sequences established the phylogenetic position of H. sinosyriacus. This research has further advanced the understanding of the phylogenetic relationships of Hibiscus spp. and related genera, and the results of the structural and variation studies will be helpful for future research.

Comparison of the chloroplast genomes and phylogenomic analysis of Elaeocarpaceae.

Elaeocarpaceae is a vital family in tropical and subtropical forests. Compared with the important position of Elaeocarpaceae species in forest ecosystem and the concern of medicinal value, the most research on Elaeocarpaceae are classification and taxonomy. Molecular systematics has corrected the morphological misjudgment, and it belongs to Oxalidales. Phylogenetic and divergence time estimates of Elaeocarpaceae is mostly constructed by using chloroplast gene fragments. At present, although there are reports on the chloroplast structure of Elaeocarpaceae, a comprehensive analysis of the chloroplast structure of Elaeocarpaceae is lacking. To understand the variation in chloroplast sequence size and structure in Elaeocarpaceae, the chloroplast genomes of nine species were sequenced using the Illumina HiSeq 2500 platform and further assembled and annotated with Elaeocarpus japonicus and Sloanea sinensis (family Elaeocarpaceae) as references. A phylogenomic tree was constructed based on the complete chloroplast genomes of the 11 species representing five genera of Elaeocarpaceae. Chloroplast genome characteristics were examined by using Circoletto and IRscope software. The results revealed the following: (a) The 11 sequenced chloroplast genomes ranged in size from 157,546 to 159,400 bp. (b) The chloroplast genomes of Elaeocarpus, Sloanea, Crinodendron and Vallea lacked the rpl32 gene in the small single-copy (SSC) region. The large single-copy (LSC) region of the chloroplast genomes lacked the ndhK gene in Elaeocarpus, Vallea stipularis, and Aristotelia fruticosa. The LSC region of the chloroplast genomes lacked the infA gene in genus Elaeocarpus and Crinodendron patagua. (c) Through inverted repeat (IR) expansion and contraction analysis, a significant difference was found between the LSC/IRB and IRA/LSC boundaries among these species. Rps3 was detected in the neighboring regions of the LSC and IRb regions in Elaeocarpus. (d) Phylogenomic analysis revealed that the genus Elaeocarpus is closely related to Crinodendron patagua on an independent branch and Aristotelia fruticosa is closely related to Vallea stipularis, forming a clade with the genus Sloanea. Structural comparisons showed that Elaeocarpaceae diverged at 60 Mya, the genus Elaeocarpus diverged 53 Mya and that the genus Sloanea diverged 0.44 Mya. These results provide new insight into the evolution of the Elaeocarpaceae.

Gene Losses and Homology of the Chloroplast Genomes of Taxillus and Phacellaria Species.

Research on the chloroplast genome of parasitic plants is limited. In particular, the homology between the chloroplast genomes of parasitic and hyperparasitic plants has not been reported yet. In this study, three chloroplast genomes of Taxillus (Taxillus chinensis, Taxillus delavayi, and Taxillus thibetensis) and one chloroplast genome of Phacellaria (Phacellaria rigidula) were sequenced and analyzed, among which T. chinensis is the host of P. rigidula. The chloroplast genomes of the four species were 119,941-138,492 bp in length. Compared with the chloroplast genome of the autotrophic plant Nicotiana tabacum, all of the ndh genes, three ribosomal protein genes, three tRNA genes and the infA gene were lost in the three Taxillus species. Meanwhile, in P. rigidula, the trnV-UAC gene and the ycf15 gene were lost, and only one ndh gene (ndhB) existed. The results of homology analysis showed that the homology between P. rigidula and its host T. chinensis was low, indicating that P. rigidula grows on its host T. chinensis but they do not share the chloroplast genome. In addition, horizontal gene transfer was not found between P. rigidula and its host T. chinensis. Several candidate highly variable regions in the chloroplast genomes of Taxillus and Phacellaria species were selected for species identification study. Phylogenetic analysis revealed that the species of Taxillus and Scurrula were closely related and supported that Scurrula and Taxillus should be treated as congeneric, while species in Phacellaria had a close relationship with that in Viscum.

Comparative Analysis and Phylogenetic Relationships of Ceriops Species (Rhizophoraceae) and Avicennia lanata (Acanthaceae): Insight into the Chloroplast Genome Evolution between Middle and Seaward Zones of Mangrove Forests.

Simple SummaryWe sequenced the complete chloroplast genomes of three Ceriops species (C. decandra, C. zippeliana, and C. tagal) and Avicennia lanata and performed comparative analyses among them. All chloroplast genomes have a circular quadripartite structure containing LSC, SSC, and two IR regions. The rpl32 gene was lost in C. zippeliana, and the infA gene was present in only A. lanata. Comparative genome analysis showed that the IR contraction or expansion events resulted in the differentiation of three genes and pseudogenes. Additionally, repeats and SSRs were identified and compared among them and other relative mangrove species. The phylogenetic analysis strongly supports that C. decandra is evolutionarily closer to C. zippeliana and A. lanata is closer to A. marina. In addition, two primer pairs were developed for species identification unique to the three Ceriops species.Ceriops and Avicennia are true mangroves in the middle and seaward zones of mangrove forests, respectively. The chloroplast genomes of Ceriops decandra, Ceriops zippeliana, and Ceriops tagal were assembled into lengths of 166,650, 166,083 and 164,432 bp, respectively, whereas Avicennia lanata was 148,264 bp in length. The gene content and gene order are highly conserved among these species. The chloroplast genome contains 125 genes in A. lanata and 129 genes in Ceriops species. Three duplicate genes (rpl2, rpl23, and trnM-CAU) were found in the IR regions of the three Ceriops species, resulting in expansion of the IR regions. The rpl32 gene was lost in C. zippeliana, whereas the infA gene was present in A. lanata. Short repeats (<40 bp) and a lower number of SSRs were found in A. lanata but not in Ceriops species. The phylogenetic analysis supports that all Ceriops species are clustered in Rhizophoraceae and A. lanata is in Acanthaceae. In a search for genes under selective pressures of coastal environments, the rps7 gene was under positive selection compared with non-mangrove species. Finally, two specific primer sets were developed for species identification of the three Ceriops species. Thus, this finding provides insightful genetic information for evolutionary relationships and molecular markers in Ceriops and Avicennia species.

Comparative and Phylogenetic Analysis of the Complete Chloroplast Genome of Santalum (Santalaceae)

Santalum (Santalaceae, sandalwood) is a hemiparasitic genus that includes approximately 15 extant species. It is known for its aromatic heartwood oil, which is used in incense and perfume. Demand for sandalwood-based products has led to drastic over-harvesting, and wild Santalum populations are now threatened. Knowledge of phylogenetic relationships will be critical for the conservation and proper management of this genus. Here, we sequenced the chloroplast genome of 11 Santalum species. The data were then used to investigate chloroplast genome evolutionary dynamics and relationships and divergence time within Santalum and related species. The Santalum chloroplast genome contains typical quadripartite structures, ranging from 143,291 to 144,263 bp. The chloroplast genome contains 110 unique genes. The whole set of ndh genes and the infA gene were found to lose their functions. The P-distance among the Santalum species was 0.0003 to 0.00828. Three mutation hotspot regions, 14 small inversions, and 460 indels events were discovered in the Santalum chloroplast genome. Branch-model-based selection analyses showed that the Santalum species were under widespread purifying selection. Our phylogenomic assessment provides an improved resolution to the phylogenetic relationships of Santalum compared to the past analyses. Our divergence time analysis showed that the crown age of Santalum was 8.46 Mya (million years ago), the first divergence occurred around 6.97 Mya, and diversification was completed approximately 1 Mya. By sequencing the 11 Santalum species chloroplast genomes, we identified the variations in the Santalum chloroplast genomes. Using the chloroplast genome sequences, phylogeny and divergence time analyses discovered that the Santalum species were likely to originate due to radiation evolution, and most speciation events occurred less than 1 Mya.

Genetic Diversity of Symbiotic Green Algae of Paramecium bursaria Syngens Originating from Distant Geographical Locations.

Paramecium bursaria (Ehrenberg 1831) is a ciliate species living in a symbiotic relationship with green algae. The aim of the study was to identify green algal symbionts of P. bursaria originating from distant geographical locations and to answer the question of whether the occurrence of endosymbiont taxa was correlated with a specific ciliate syngen (sexually separated sibling group). In a comparative analysis, we investigated 43 P. bursaria symbiont strains based on molecular features. Three DNA fragments were sequenced: two from the nuclear genomes—a fragment of the ITS1-5.8S rDNA-ITS2 region and a fragment of the gene encoding large subunit ribosomal RNA (28S rDNA), as well as a fragment of the plastid genome comprising the 3′rpl36-5′infA genes. The analysis of two ribosomal sequences showed the presence of 29 haplotypes (haplotype diversity Hd = 0.98736 for ITS1-5.8S rDNA-ITS2 and Hd = 0.908 for 28S rDNA) in the former two regions, and 36 haplotypes in the 3′rpl36-5′infA gene fragment (Hd = 0.984). The following symbiotic strains were identified: Chlorella vulgaris, Chlorella variabilis, Chlorella sorokiniana and Micractinium conductrix. We rejected the hypotheses concerning (i) the correlation between P. bursaria syngen and symbiotic species, and (ii) the relationship between symbiotic species and geographic distribution.

Comparison of Chloroplast Genomes among Species of Unisexual and Bisexual Clades of the Monocot Family Araceae.

The chloroplast genome provides insight into the evolution of plant species. We de novo assembled and annotated chloroplast genomes of four genera representing three subfamilies of Araceae: Lasia spinosa (Lasioideae), Stylochaeton bogneri, Zamioculcas zamiifolia (Zamioculcadoideae), and Orontium aquaticum (Orontioideae), and performed comparative genomics using these chloroplast genomes. The sizes of the chloroplast genomes ranged from 163,770 bp to 169,982 bp. These genomes comprise 113 unique genes, including 79 protein-coding, 4 rRNA, and 30 tRNA genes. Among these genes, 17–18 genes are duplicated in the inverted repeat (IR) regions, comprising 6–7 protein-coding (including trans-splicing gene rps12), 4 rRNA, and 7 tRNA genes. The total number of genes ranged between 130 and 131. The infA gene was found to be a pseudogene in all four genomes reported here. These genomes exhibited high similarities in codon usage, amino acid frequency, RNA editing sites, and microsatellites. The oligonucleotide repeats and junctions JSB (IRb/SSC) and JSA (SSC/IRa) were highly variable among the genomes. The patterns of IR contraction and expansion were shown to be homoplasious, and therefore unsuitable for phylogenetic analyses. Signatures of positive selection were seen in three genes in S. bogneri, including ycf2, clpP, and rpl36. This study is a valuable addition to the evolutionary history of chloroplast genome structure in Araceae.

The complete chloroplast genome of a hemiparasitic plant Santalum boninense (Santalaceae), endemic to the Bonin (Ogasawara) Islands

The complete chloroplast genome sequence of a hemiparasitic plant Santalum boninense (Santalaceae) was determined and described in this study. The chloroplast genome was 144,263 bp in length, consisting of a large single-copy region (83,912 bp), a small single-copy region (11,349 bp), and inverted repeats (24,501 bp). The chloroplast genome contained 124 genes including 72 protein-coding genes, 35 tRNA genes, eight rRNA genes, and nine pseudogenes. All the ndh genes and infA gene were found to lose function by gene loss or pseudogenization. GC content of the whole chloroplast genome was 38.0%.

Abstract GS2-01: High levels of interferon-response gene signatures are associated with de novo and acquired resistance to CDK4/6 inhibitors in ER+ breast cancer

Abstract Background: The CDK4/6 inhibitors (i) palbociclib (Palbo), ribociclib, and abemaciclib remarkably improved the outcome of patients with metastatic ER+/HER2- breast cancer (BC) and are now under clinical investigation in early BC. Despite high efficacy, de novo and acquired resistance to CDK4/6i is common. Elucidating the molecular basis for sensitivity and resistance to CDK4/6i is crucial to identify predictive biomarkers and novel therapeutic targets to improve patient outcome. Materials and Methods: MCF7, T47D and ZR75-1 parental (P) BC cells and their derivatives made resistant to tamoxifen, estrogen deprivation (EDR), or fulvestrant were used. The P and EDR models of MCF7 and T47D cells were chronically exposed to increasing concentrations of Palbo to generate derivatives with acquired resistance to Palbo (PalboR). The transcriptomic profiles of P, endocrine-resistant (EndoR) and PalboR models were determined by RNA-seq. IC50s were determined by exposing MCF7, T47D, and ZR75-1 P and EndoR lines (n=12) to increasing concentrations of Palbo. Cell growth was assessed by methylene blue staining, and changes in the mRNA and protein levels of key cell cycle molecules were assessed by RT-PCR and Western blot, respectively. Gene expression data from the Cancer Dependency Map (DepMap), baseline tumors from the NeoPalAna (NCT01723774) and neoMONARCH (NCT02441946) neoadjuvant trials, as well as the TCGA and METABRIC datasets were interrogated for correlations of gene signatures and patient outcome (by KMPlot). Results: Palbo treatment resulted in a dose-dependent inhibition of the growth of P and EndoR BC cell lines, with varying degree of sensitivity among the models. GSEA analysis comparing the least sensitive (IC50&amp;gt;350nM) vs. the most sensitive (IC50&amp;lt;100) cell lines identified the ‘interferon gamma response’ (IFNg) and ‘interferon alpha response’ (IFNa) as the top-ranked hallmark enriched signatures. Likewise, DepMap analysis of ER+/HER2- BC cell lines (n=11) revealed that cells with low CDK4 dependency scores displayed high IFN-signaling. We derived a 35-gene signature (termed ‘IFN-Related Palbociclib-Resistance Signature’, IRPS) comprised of genes belonging to the INFg and INFa gene sets that positively correlated with the Palbo IC50 values of our collection of P and EndoR lines. To extend these findings to primary ER+ BC, we interrogated transcriptomic data from the NeoPalAna and neoMONARCH trials that evaluated neoadjuvant CDK4/6i with endocrine therapy. In both trials, the IFNg, IFNa, and IRPS gene signatures were highly enriched in patients with tumors exhibiting intrinsic resistance to CDK4/6i. We next investigated the underlying molecular changes and their association with IFN-signaling in our acquired resistant PalboR cell lines. Compared to the untreated cells, the PalboR models commonly displayed alterations in several components of the cyclin D-CDK4/6-Rb axis, including elevated expression of cyclin-D1, -E1, and CDK6, and reduced levels of Rb. Notably, the PalboR derivatives commonly displayed a dramatic activation of IFN/STAT1-signaling compared to their short-term treated or untreated counterparts. In primary ER+/HER2- tumors, the IRPS score was significantly higher in lumB vs. lumA subtype and correlated with increased gene expression of immune checkpoints (PD-1, PD-L1, CTLA-4), endocrine-resistance, and poor prognosis. Conclusion: Aberrant IFN-signaling predicts resistance to CDK4/6i in both ER+/HER2- BC cell lines and in primary BCs from neoadjuvant clinical trials. Experimentally, acquired resistance to Palbo is associated with activation of the IFN-pathway suggesting its involvement in resistance to CDK4/6i. Future studies are warranted to provide mechanistic insights into the association of IFN-signaling with response to CDK4/6i. Citation Format: Carmine De Angelis, Xiaoyong Fu, Maria Letizia Cataldo, Agostina Nardone, Valerie M. Jansen, Jamunarani Veeraraghavan, Sarmistha Nanda, Lanfang Qin, Vidyalakshmi Sethunath, Resel Pereira, Matteo Benelli, Ilenia Migliaccio, Luca Malorni, Joshua Donaldson, Pier Selenica, David N. Brown, Britta Weigelt, Jorge S. Reis-Filho, Ben H. Park, Sara A. Hurvitz, Dennis J. Slamon, Mothaffar F. Rimawi, Rinath Jeselsohn, Kent Osborne, Rachel Schiff. High levels of interferon-response gene signatures are associated with de novo and acquired resistance to CDK4/6 inhibitors in ER+ breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS2-01.

Characterization of the complete chloroplast genome of leek Allium porrum L. (Amaryllidaceae)

The complete chloroplast genome sequence of Allium porrum was determined by Illumina single-end sequencing. The complete plastid genome was 152,732 bp in length containing a large single copy (LSC) of 81,744 bp and a small single copy (SSC) of 17,910 bp, which were separated by a pair of 26,524 bp inverted repeats (IRs). A total of 133 genes were annotated, including 80 protein-coding genes, 38 tRNA genes, 8 rRNA genes, and 7 pseudogenes. The overall GC contents of the plastid genome were 36.7%. Unlike A. sativum and A. obliquum in the leek, plastome infA gene is absent, and rpl23 gene is a pseudogene due to a 4 bp deletion and the formation of a premature stop codon.

Plastome phylogenomics of the early-diverging eudicot family Berberidaceae

The relationships among the genera of the early-diverging eudicot family Berberidaceae have long been controversial. To resolve these relationships and to better understand plastome evolution within the family, we sequenced the complete plastome sequences of ten Berberidaceae genera, combined these with six existing plastomes for the family, and conducted a series of phylogenomic analyses on the resulting data set. Five of the newly sequenced plastomes were found to possess the typical angiosperm plastome complement of 79 protein-coding genes, 4 rRNA genes, and 30 tRNA genes. The infA gene was found to be pseudogenized in Bongardia, Diphylleia, Dysosma and Vancouveria; rps7 was found to be severely truncated in Diphylleia, Dysosma and Podophyllum; clpP was found to be highly divergent in Vancouveria; and a ∼19 kb inversion was detected in Bongardia. Maximum likelihood phylogenetic analyses of a 79-gene, 24-taxon data set including nearly all genera of Berberidaceae recovered four chromosome groups (x = 6, 7, 8, 10), resolved the x = 8 group as the sister to the x = 10 group, and supported the monophyly of the clade comprising x = 7, 8, 10. The generic relationships within each group were all resolved with high support. Based on gene presence within the Inverted Repeat (IR), a total of seven plastome IR types were identified within Berberidaceae. Biogeographical analysis indicated the origin and diversification of Berberidaceae has likely been strongly influenced by the distribution of its favored habitat: temperate forests.

Complete chloroplast genome of Tetragonia tetragonioides: Molecular phylogenetic relationships and evolution in Caryophyllales.

The chloroplast genome of Tetragonia tetragonioides (Aizoaceae; Caryophyllales) was sequenced to provide information for studies on phylogeny and evolution within Caryophyllales. The chloroplast genome of Tetragonia tetragonioides is 149,506 bp in length and includes a pair of inverted repeats (IRs) of 24,769 bp that separate a large single copy (LSC) region of 82,780 bp and a small single copy (SSC) region of 17,188 bp. Comparative analysis of the chloroplast genome showed that Caryphyllales species have lost many genes. In particular, the rpl2 intron and infA gene were not found in T. tetragonioides, and core Caryophyllales lack the rpl2 intron. Phylogenetic analyses were conducted using 55 genes in 16 complete chloroplast genomes. Caryophyllales was found to divide into two clades; core Caryophyllales and noncore Caryophyllales. The genus Tetragonia is closely related to Mesembryanthemum. Comparisons of the synonymous (Ks), nonsynonymous (Ka), and Ka/Ks substitution rates revealed that nonsynonymous substitution rates were lower than synonymous substitution rates and that Ka/Ks rates were less than 1. The findings of the present study suggest that most genes are a purified selection.

Characterization of the complete plastid genome of lop-sided onion Allium obliquum L. (Amaryllidaceae)

The complete chloroplast genome sequence of Allium obliquum was determined by Illumina single-end sequencing. The complete plastid genome was 152,387 bp in length, containing a large single copy (LSC) of 81,588 bp and a small single copy (SSC) of 18,059 bp, which were separated by a pair of 26,370 bp inverted repeats (IRs). A total of 134 genes were annotated, including 83 protein coding genes, 38 tRNA genes, eight rRNA genes, and five pseudogenes. The overall GC contents of the plastid genome were 36.8%. Unlike A. cepa (onion) and A. sativum (garlic), A. obliquum encodes a functional intact infA gene.

The complete plastome of tropical fruit Garcinia mangostana (Clusiaceae)

The complete plastome sequence of Garcinia mangostana L. (Clusiaceae) is completed in this study (NCBI acc. no. KX822787). This is a first complete plastome sequence from the Clusiaceae. The complete plastome size is 158,179 bp in length and consists of a large single copy of 86,458 bp and a small single copy of 17,703 bp, separated by two inverted repeats of 27,009 bp. The G. mangostana plastome shows four minor structural modifications including infA gene loss, rpl32 gene loss, ycf3 gene intron loss and a 363 bp inversion between trnV-UAC and atpE gene. The plastome contains 111 genes, of which 77 are protein-coding genes, 30 are tRNA genes and four are rRNA genes. The average A-T content of the plastome is 63.9%. A total of 110 simple sequence loci are identified from the genome. Phylogenetic analysis reveals that G. mangostana is a sister group of Erythroxylum novogranatense (Erythroxylaceae) with 78% bootstrap support.

Gene losses and partial deletion of small single-copy regions of the chloroplast genomes of two hemiparasitic Taxillus species

Numerous variations are known to occur in the chloroplast genomes of parasitic plants. We determined the complete chloroplast genome sequences of two hemiparasitic species, Taxillus chinensis and T. sutchuenensis, using Illumina and PacBio sequencing technologies. These species are the first members of the family Loranthaceae to be sequenced. The complete chloroplast genomes of T. chinensis and T. sutchuenensis comprise circular 121,363 and 122,562 bp-long molecules with quadripartite structures, respectively. Compared with the chloroplast genomes of Nicotiana tabacum and Osyris alba, all ndh genes as well as three ribosomal protein genes, seven tRNA genes, four ycf genes, and the infA gene of these two species have been lost. The results of the maximum likelihood and neighbor-joining phylogenetic trees strongly support the theory that Loranthaceae and Viscaceae are monophyletic clades. This research reveals the effect of a parasitic lifestyle on the chloroplast structure and genome content of T. chinensis and T. sutchuenensis, and enhances our understanding of the discrepancies in terms of assembly results between Illumina and PacBio.