The Complete Chloroplast Genome of Arabidopsis thaliana Isolated in Korea (Brassicaceae): An Investigation of Intraspecific Variations of the Chloroplast Genome of Korean A. thaliana

Characterization of the complete chloroplast genome of Eutrema deltoideum (Brassicaceae)

Eutrema deltoideum (Hook. f. et Thoms.) has been recognized as a potentially important vegetable and medicinal resource. In this study, we present the complete chloroplast genome of E. deltoideum and conduct a phylogenetic analysis. The chloroplast genome is 154,051 bp long and consists of a large single-copy (LSC) region of 84,149 bp, two inverted repeat (IR) regions of 26,065 bp each, and a small single-copy (SSC) region of 17,772 bp. It contains 132 complete genes, including 87 protein-coding genes, 8 ribosomal RNA genes, and 37 tRNA genes. Additionally, we identified 78 simple sequence repeats (SSRs). The phylogenetic tree reveals that E. deltoideum is closely related to E. heterophyllum, and the Eutrema genus is monophyletic. This study provides valuable information about E. deltoideum and enhances our understanding of its taxonomic classification.

The complete chloroplast genome of Spergularia marina (Caryophyllaceae) and its phylogenetic analysis

Spergularia marina (L.) Griseb, 1843 (Caryophyllaceae) is a halophytic plant widely distributed along the southwestern coast of the Korean Peninsula. In this study, the complete chloroplast genome sequence of S. marina was determined using next-generation sequencing (NGS). The chloroplast genome of S. marina is 152,460 bp in length with 36.7% GC content. It comprises a large single-copy (LSC; 83,321), a small single copy (SSC; 17,205 bp), and a pair of inverted repeats (IRs; 25,967 bp) with a typical quadripartite structure. It consists of 131 genes, including 86 protein-coding genes, 8 ribosomal RNAs, and 37 transfer RNAs. Phylogenetic analysis using complete chloroplast genomes showed that among the 17 Caryophyllaceae species, S. marina is most closely related to Spergula arvensis. Since no complete chloroplast genome of the genus Spergularia has been reported to date, our study provides useful genetic information for determining phylogenetic relationships within the Caryophyllaceae.

The complete mitochondrial genome of Aclees taiwanensis Kôno, 1933 (Coleoptera: Curculionidae)

We sequenced the complete mitochondrial genome of Aclees taiwanensis collected in Korea. The circular mitogenome of A. taiwanensis is 17,435 bp, longer than that of Aclees cribratus, and includes 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a control region/D-loop. The AT ratio is 75.4%. Maximum-likelihood and Bayesian inference phylogenetic trees showed that A. taiwanensis was clustered with A. cribratus with full-support values for both trees.

The Complete Chloroplast Genomes of Primula obconica Provide Insight That Neither Species nor Natural Section Represent Monophyletic Taxa in Primula (Primulaceae)

The genus Primula (Primulaceae) comprises more than 500 species, with 300 species distributed in China. The contradictory results between systematic analyses and morphology-based taxonomy make taxonomy studies difficult. Furthermore, frequent introgression between closely related species of Primula can result in non-monophyletic species. In this study, the complete chloroplast genome of sixteen Primula obconica subsp. obconica individuals were assembled and compared with 84 accessions of 74 species from 21 sections of the 24 sections of the genus in China. The plastome sizes of P. obconica subsp. obconica range from 153,584 bp to 154,028 bp. Genome-wide variations were detected, and 1915 high-quality SNPs and 346 InDels were found. Most SNPs were detected in downstream and upstream gene regions (45.549% and 41.91%). Two cultivated accessions, ZP1 and ZP2, were abundant with SSRs. Moreover, 12 SSRs shared by 9 accessions showed variations that may be used as molecular markers for population genetic studies. The phylogenetic tree showed that P. obconica subsp. obconica cluster into two independent clades. Two subspecies have highly recognizable morphological characteristics, isolated geographical distribution areas, and distinct phylogenetic relationships compared with P. obconica subsp. obconica. We elevate the two subspecies of P. obconica to separate species. Our phylogenetic tree is largely inconsistent with morphology-based taxonomy. Twenty-one sections of Primula were mainly divided into three clades. The monophyly of Sect. Auganthus, Sect. Minutissimae, Sect. Sikkimensis, Sect. Petiolares, and Sect. Ranunculoides are well supported in the phylogenetic tree. The Sect. Obconicolisteri, Sect. Monocarpicae, Sect. Carolinella, Sect. Cortusoides, Sect. Aleuritia, Sect. Denticulata, Sect. Proliferae Pax, and Sect. Crystallophlomis are not a monophyletic group. The possible explanations for non-monophyly may be hybridization, polyploidization, recent introgression, incorrect taxonomy, or chloroplast capture. Multiple genomic data and population genetic studies are therefore needed to reveal the evolutionary history of Primula. Our results provided valuable information for intraspecific variation and phylogenetic relationships within Primula.

Haplotype Analysis of Chloroplast Genomes for Jujube Breeding

Jujube (family Rhamnaceae) is an important economic fruit tree in China. In this study, we reported 26 chloroplast (cp) sequences of jujube using Illumina paired-end sequencing. The sequence length of cp genome was 161, 367-161, 849 bp, which was composed of a large single-copy region (89053-89437 bp) and a small single-copy region (19356-19362 bp) separated by a pair of reverse repeat regions (26478-26533 bp). Each cp genome encodes the same 130 genes, including 112 unique genes, being quite conserved in genome structure and gene sequence. A total of 118 single base substitutions (SNPs) and 130 InDels were detected in 65 jujube accessions. Phylogenetic and haplotype network construction methods were used to analyze the origin and evolution of jujube and its sour-tasting relatives. We detected 32 effective haplotypes, consisting of 20 unique jujube haplotypes and 9 unique sour-jujube haplotypes. Compared with sour-jujube, jujube showed greater haplotype diversity at the chloroplast DNA level. To cultivate crisp and sweet fruit varieties featuring strong resistance, by combining the characteristics of sour-jujube and cultivated jujube, three hybrid combinations were suggested for reciprocal crosses: "Dongzao" × "Jingzao39," "Dongzao" × "Jingzao60," "Dongzao" × "Jingzao28." This study provides the basis for jujube species' identification and breeding, and lays the foundation for future research.

Chloroplast Genomic Variation in Euonymus maackii Rupr. and Its Differentiation Time in Euonymus

Euonymus maackii Rupr. is a small deciduous tree belonging to family Celastraceae. It is an important ornamental tree and a potential medicinal plant resource. Here, we assembled and annotated the chloroplast (cp) genome of E. maackii. By combining this genome with seven available cp genomes from Euonymus species, we performed plastome variation analysis of E. maackii and Euonymus. Furthermore, we reconstructed a phylogenetic tree and estimated the differentiation time of E. maackii. The newly assembled cp genome of E. maackii was 157,551 bp in size and had a typical quadripartite structure, which consisted of one large single-copy (LSC 86,524 bp) region, one small single-copy (SSC 18,337 bp) region, and a pair of inverted repeat regions (26,345 bp). A total of 652 single nucleotide polymorphisms (SNPs) and 65 insertions/deletions (indels) were detected between the two cp genomes of E. maackii, with overall genetic variation of 4.1 SNPs per kb or a π value of 0.00443, reflecting a high level of intraspecific variation. Some coding and noncoding regions with higher variation were identified, including trnV-UAC, petN, ycf1-ndhF, trnM-CAU-atpE, rpl2-rpl23, psbZ-trnG-GCC, trnY-GUA-trnE-UUC, trnW-CCA-trnP-UGG, rps16-trnQ-UUG, and psbC-trnS-UGA. The hypervariable coding and noncoding regions in E. maackii were not the same as those in Euonymus. The phylogenetic tree and divergence time based on the whole cp genomes showed that the seven Euonymus species formed a clade, which was sister to that formed with Catha edulis and Maytenus guangxiensis, and they separated 24.74 million years ago. E. maackii and E. hamiltonianus were most closely related, having separated from each other only approximately 2.68 million years ago. Our study provides important genetic information for further studies of E. maackii, such as studies on its phylogeography, population genetics and molecular ecology, and provides new insights into the evolution of the cp genome in Euonymus.

The investigation of intraspecific characteristics and comparative analyses of the complete mitochondrial genome of Stegobium paniceum (Linnaeus, 1758) (Coleoptera: Ptinidae) assembled from public NGS raw reads of the black truffle, Tuber melanosporum

Due to the rapid development of NGS technologies, a huge amount of NGS raw reads have been accumulated in public repositories, such as the Short Read Archive of NCBI. We successfully rescued the complete mitochondrial genome of Stegobium paniceum, a drug store beetle, from public NGS raw reads of truffle generated from the whole genome project. The circular mitogenome of S. paniceum is 15,474 bp long including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large non-coding region of 803 bp. Intraspecific transfer RNAs structure and sequence variations were investigated and simple sequence repeats identified from three S. paniceum mitochondrial genomes were compared showing their diversities as fundamental data to utilize them in various aspects including developing efficient molecular markers in the family, Ptinidae. Phylogenetic analysis of 23 Bostrichoidea mitochondrial genomes presented better species identification based on phylogenetic analyses and the optimal options for constructing phylogenetic trees based on Bostrichoidea mitochondrial genomes. Our results present not only utilization of public NGS raw read sequences but also intraspecific features of S. paniceum mitochondrial genomes and comparative analysis of Bostrichoidea mitochondrial genomes in various aspects.

A New Mitochondrial Genome of Sogatella furcifera (Horváth) (Hemiptera: Delphacidae) and Mitogenome-Wide Investigation on Polymorphisms

Simple Summary

We completed one mitogenome of white-backed planthopper (WBPH), Sogatella furcifera (Horváth), with finding heteroplasmy phenomenon confirmed by PCR reaction and Sanger sequencing method. This heteroplasmy was not observed in WBPHs (n = 24) collected from the fields, suggesting that it may be uncommon in fields. We also analyzed single nucleotide polymorphisms, insertion and deletions, and simple sequence repeats among three currently available WBPH mitogenomes of Korea and China, suggesting that identified intraspecific variations could be potential candidates for developing markers to distinguish geographical populations of WBPH including Korean and Chinese. Phylogenetic analysis of 32 mitogenomes of Delphacidae including the three WBPH mitogenomes suggested that Delphacinae seems to be monophyletic and Sogatella species including WBPH are clearly formed as one clade.

Abstract

White-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the major sap-sucking rice pests in East Asia. We have determined a new complete mitochondrial genome of WBPH collected in the Korean peninsula using NGS technology. Its length and GC percentages are 16,613 bp and 23.8%, respectively. We observed one polymorphic site, a non-synonymous change, in the COX3 gene with confirmation heteroplasmy phenomenon within individuals of WBPH by PCR amplification and Sanger sequencing, the first report in this species. In addition, this heteroplasmy was not observed in wild WBPH populations, suggesting that it may be uncommon in fields. We analyzed single nucleotide polymorphisms, insertion, and deletions, and simple sequence repeats among the three WBPH mitogenomes from Korea and China and found diverse intraspecific variations, which could be potential candidates for developing markers to distinguish geographical populations. Phylogenetic analysis of 32 mitogenomes of Delphacidae including the three WBPH mitogenomes suggested that Delphacinae seems to be monophyletic and Sogatella species including WBPH are clearly formed as one clade. In the future, it is expected that complete mitogenomes of individuals of geographically dispersed WBPH populations will be used for further population genetic studies to understand the migration pathway of WBPH.

Genome-wide comparative analyses of GATA transcription factors among seven Populus genomes

GATA transcription factors (TFs) are widespread eukaryotic regulators whose DNA-binding domain is a class IV zinc finger motif (CX2CX17-20CX2C) followed by a basic region. We identified 262 GATA genes (389 GATA TFs) from seven Populus genomes using the pipeline of GATA-TFDB. Alternative splicing forms of Populus GATA genes exhibit dynamics of GATA gene structures including partial or full loss of GATA domain and additional domains. Subfamily III of Populus GATA genes display lack CCT and/or TIFY domains. 21 Populus GATA gene clusters (PCs) were defined in the phylogenetic tree of GATA domains, suggesting the possibility of subfunctionalization and neofunctionalization. Expression analysis of Populus GATA genes identified the five PCs displaying tissue-specific expression, providing the clues of their biological functions. Amino acid patterns of Populus GATA motifs display well conserved manner of Populus GATA genes. The five Populus GATA genes were predicted as membrane-bound GATA TFs. Biased chromosomal distributions of GATA genes of three Populus species. Our comparative analysis approaches of the Populus GATA genes will be a cornerstone to understand various plant TF characteristics including evolutionary insights.

The complete chloroplast genome sequence of new species candidate of Plantago depressa Willd. in Korea (Plantaginaceae)

We presented a complete chloroplast genome of a new species candidate of Plantago depressa, Willd. named as Plantago wonjuenesis sp. nov, which is 164,946 bp long (GC ratio is 38.0%) and has four subregions: 82,985 bp of large single copy and 4,647 bp of small single-copy regions are separated by 38,657 bp of inverted repeat regions including 94 protein-coding genes (PCGs), eight rRNAs, and 38 tRNAs. Number of variations between P. wonjuenesis and P. depressa can be considered as interspecific variations. Bootstrapped phylogenetic trees constructed with conserved 78 PCGs of eleven Plantaginaceae chloroplast genomes present that P. wonjuensis is clustered with P. depressa, P. fengdouensis, and P. media.

A Comparative Analyses of the Complete Mitochondrial Genomes of Fungal Endosymbionts in Sogatella furcifera, White-Backed Planthoppers

Sogatella furcifera Horvath, commonly known as the white-backed planthoppers (WBPH), is an important pest in East Asian rice fields. Fungal endosymbiosis is widespread among planthoppers in the infraorder Fulgoromorpha and suborder Auchenorrhyncha. We successfully obtained complete mitogenome of five WBPH fungal endosymbionts, belonging to the Ophiocordycipitaceae family, from next-generation sequencing (NGS) reads obtained from S. furcifera samples. These five mitogenomes range in length from 55,390 bp to 55,406 bp, which is shorter than the mitogenome of the fungal endosymbiont found in Ricania speculum, black planthoppers. Twenty-eight protein-coding genes (PCGs), 12 tRNAs, and 2 rRNAs were found in the mitogenomes. Two single-nucleotide polymorphisms, two insertions, and three deletions were identified among the five mitogenomes, which were fewer in number than those of four species of Ophiocordycipitaceae, Ophiocordyceps sinensis, Hirsutella thompsonii, Hirsutella rhossiliensis, and Tolypocladium inflatum. Noticeably short lengths (up to 18 bp) of simple sequence repeats were identified in the five WBPH fungal endosymbiont mitogenomes. Phylogenetic analysis based on conserved PCGs across 25 Ophiocordycipitaceae mitogenomes revealed that the five mitogenomes were clustered with that of R. speculum, forming an independent clade. In addition to providing the full mitogenome sequences, obtaining complete mitogenomes of WBPH endosymbionts can provide insights into their phylogenetic positions without needing to isolate the mtDNA from the host. This advantage is of value to future studies involving fungal endosymbiont mitogenomes.

Genome-wide comparative analyses of GATA transcription factors among 19 Arabidopsis ecotype genomes: Intraspecific characteristics of GATA transcription factors

GATA transcription factors (TFs) are widespread eukaryotic regulators whose DNA-binding domain is a class IV zinc finger motif (CX2CX17-20CX2C) followed by a basic region. Due to the low cost of genome sequencing, multiple strains of specific species have been sequenced: e.g., number of plant genomes in the Plant Genome Database (http://www.plantgenome.info/) is 2,174 originated from 713 plant species. Thus, we investigated GATA TFs of 19 Arabidopsis thaliana genome-widely to understand intraspecific features of Arabidopsis GATA TFs with the pipeline of GATA database (http://gata.genefamily.info/). Numbers of GATA genes and GATA TFs of each A. thaliana genome range from 29 to 30 and from 39 to 42, respectively. Four cases of different pattern of alternative splicing forms of GATA genes among 19 A. thaliana genomes are identified. 22 of 2,195 amino acids (1.002%) from the alignment of GATA domain amino acid sequences display variations across 19 ecotype genomes. In addition, maximally four different amino acid sequences per each GATA domain identified in this study indicate that these position-specific amino acid variations may invoke intraspecific functional variations. Among 15 functionally characterized GATA genes, only five GATA genes display variations of amino acids across ecotypes of A. thaliana, implying variations of their biological roles across natural isolates of A. thaliana. PCA results from 28 characteristics of GATA genes display the four groups, same to those defined by the number of GATA genes. Topologies of bootstrapped phylogenetic trees of Arabidopsis chloroplasts and common GATA genes are mostly incongruent. Moreover, no relationship between geographical distribution and their phylogenetic relationships was found. Our results present that intraspecific variations of GATA TFs in A. thaliana are conserved and evolutionarily neutral along with 19 ecotypes, which is congruent to the fact that GATA TFs are one of the main regulators for controlling essential mechanisms, such as seed germination and hypocotyl elongation.

Decoding first complete chloroplast genome of toothbrush tree (Salvadora persica L.): insight into genome evolution, sequence divergence and phylogenetic relationship within Brassicales

BACKGROUND

Salvadora persica L. (Toothbrush tree - Miswak; family-Salvadoraceae) grows in the arid-land ecosystem and possesses economic and medicinal importance. The species, genus and the family have no genomic datasets available specifically on chloroplast (cp) genomics and taxonomic evolution. Herein, we have sequenced the complete chloroplast genome of S. persica for the first time and compared it with 11 related specie's cp genomes from the order Brassicales.

RESULTS

The S. persica cp genome was 153,379 bp in length containing a sizeable single-copy region (LSC) of 83,818 bp which separated from the small single-copy region (SSC) of 17,683 bp by two inverted repeats (IRs) each 25,939 bp. Among these genomes, the largest cp genome size (160,600 bp) was found in M. oleifera, while in S. persica it was the smallest (153,379 bp). The cp genome of S. persica encoded 131 genes, including 37 tRNA genes, eight rRNA genes and 86 protein-coding genes. Besides, S. persica contains 27 forward, 36 tandem and 19 palindromic repeats. The S. persica cp genome had 154 SSRs with the highest number in the LSC region. Complete cp genome comparisons showed an overall high degree of sequence resemblance between S. persica and related cp genomes. Some divergence was observed in the intergenic spaces of other species. Phylogenomic analyses of 60 shared genes indicated that S. persica formed a single clade with A. tetracantha with high bootstrap values. The family Salvadoraceae is closely related to Capparaceae and Petadiplandraceae rather than to Bataceae and Koberliniacaea.

CONCLUSION

The current genomic datasets provide pivotal genetic resources to determine the phylogenetic relationships, genome evolution and future genetic diversity-related studies of S. persica in complex angiosperm families.

The Comparative Analyses of Six Complete Chloroplast Genomes of Morphologically Diverse Chenopodium album L. (Amaranthaceae) Collected in Korea

Chenopodium album sensu stricto belonging to C. album aggregate is an annual cosmopolitan weed displaying the diversity of morphologies. We completed the six chloroplast genomes of C. album s. str. collected in Korea to understand the relationship between the diversity of chloroplast genomes and their morphological variations. All six C. album chloroplast genomes have a typical quadripartite structure with length ranging from 151,906 bp to 152,199 bp, similar to the previously sequenced C. album chloroplast genome (NC_034950). In total, 56 single nucleotide polymorphisms (SNPs) and 26 insertion and deletion (INDEL) regions (308 bp in total) were identified from the six chloroplast genomes, presenting a low level of intraspecific variations in comparison to the other angiosperm species. 376 normal simple sequence repeats were identified in all seven C. album chloroplast genomes. The phylogenetic analysis based on all available complete Amaranthaceae chloroplast genomes presents phylogenetic positions of six C. album samples as well as correlation with one of C. album morphological features. Our results provide the way to investigate intraspecific features of C. album chloroplast genomes and also the insights of understanding various intraspecific characteristics including morphological features.

Complete Chloroplast Genome of Clethra fargesii Franch., an Original Sympetalous Plant from Central China: Comparative Analysis, Adaptive Evolution, and Phylogenetic Relationships

Clethra fargesii, an essential ecological and endemic woody plant of the genus Clethra in Clethraceae, is widely distributed in Central China. So far, there have been a paucity of studies on its chloroplast genome. In the present study, we sequenced and assembled the complete chloroplast genome of C. fargesii. We also analyzed the chloroplast genome features and compared them to Clethra delavayi and other closely related species in Ericales. The complete chloroplast genome is 157,486 bp in length, including a large single-copy (LSC) region of 87,034 bp and a small single-copy (SSC) region of 18,492 bp, separated by a pair of inverted repeat (IR) regions of 25,980 bp. The GC content of the whole genome is 37.3%, while those in LSC, SSC, and IR regions are 35.4%, 30.7%, and 43.0%, respectively. The chloroplast genome of C. fargesii encodes 132 genes in total, including 87 protein-coding genes (PCGs), 37 tRNA genes, and eight rRNA genes. A total of 26,407 codons and 73 SSRs were identified in C. fargesii chloroplast genome. Additionally, we postulated and demonstrated that the structure of the chloroplast genome in Clethra species may present evolutionary conservation based on the comparative analysis of genome features and genome alignment among eight Ericales species. The low Pi values revealed evolutionary conservation based on the nucleotide diversity analysis of chloroplast genome in two Clethra species. The low selection pressure was shown by a few positively selected genes by adaptive evolution analysis using 80 coding sequences (CDSs) of the chloroplast genomes of two Clethra species. The phylogenetic tree showed that Clethraceae and Ericaceae are sister clades, which reconfirm the previous hypothesis that Clethra is highly conserved in the chloroplast genome using 75 CDSs of chloroplast genome among 40 species. The genome information and analysis results presented in this study are valuable for further study on the intraspecies identification, biogeographic analysis, and phylogenetic relationship in Clethraceae.

The complete chloroplast genome of Aruncus dioicus var. kamtschaticus (Rosaceae)

Aruncus dioicus var. kamtschaticus is an economically important herb in the cold temperate regions of East Asia, and displays highly variable morphological features. Completed chloroplast genome of A. dioicus var. kamtschaticus isolated in Korea is 157,859 bp long with four subregions: 85,972 bp of large single copy and 19,185 bp of small single-copy regions separated by 26,351 bp of inverted repeat regions. The genome includes 131 genes (86 protein-coding genes, eight rRNAs, and 37 tRNAs). Phylogenetic analyses show that our chloroplast genome was clustered with two partial chloroplast genomes of A. dioicus.

Comprehensive Analyses of the Complete Mitochondrial Genome of Figulus binodulus (Coleoptera: Lucanidae)

Figulus binodulus Waterhouse is a small stag beetle distributed in East Asia. We determined the first mitochondrial genome of F. binodulus of which is 16,261-bp long including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large noncoding region of 1,717 bp. Gene order of F. binodulus is identical to the ancestral insect mitochondrial gene order as in most other stag beetle species. All of 22 tRNAs could be shaped into typical clover-leaf structure except trnSer1. Comparative analyses of 21 Lucanidae mitochondrial genomes was conducted in aspect of their length and AT-GC ratio. Nucleotide diversities analyses provide that cox1 and cox2 in Lucanidae are less diverse than those of Scarabaeoidea. Fifty simple sequence repeats (SSRs) were identified on F. binodulus mitochondrial genome. Comparative analysis of SSRs among five mitochondrial genomes displayed similar trend along with SSR types. Figulus binodulus was sister to all other available family Lucanidae species in the phylogenetic tree.