CPGAVAS2, an integrated plastome sequence annotator and analyzer

The complete chloroplast genome of Semiaquilegia danxiashanensis (Ranunculaceae), a rare species endemic to Danxia landform in Guangdong, China

Semiaquilegia danxiashanensis is currently known only from the type locality, Danxia Mountain, characterized by its spectacular red sandstone cliffscape. In this study, we assembled the complete chloroplast genome sequence of S. danxiashanensis and inferred its phylogenetic relationships. Total length of the chloroplast genome was 160,548 bp, with an overall GC content of 39%. The chloroplast genome had typical quadripartite structure and contained one LSC region (89,882 bp) and one SSC region (17,386 bp), which were separated by two IRs regions (26,640 bp, respectively). It comprised 133 genes, including 84 protein coding genes, 41 tRNA genes and eight rRNA genes. The maximum likelihood phylogenetic analysis indicated that S. danxiashanensis was sister to S. adoxoides; meanwhile, Semiaquilegia was closely related to both Urophysa and Aquilegia in Ranunculaceae. This study sheds light on the evolutionary history of Semiaquilegia and provides preliminary data for future comparative analysis of chloroplast genomes.

Plastomes of Nothofagus reflect a shared biogeographic history in Patagonia

Plastomes are used in phylogenetic reconstructions because of their relatively conserved nature. Nonetheless, some limitations arise, particularly at lower taxonomic levels due to reduced interspecific polymorphisms and frequent hybridization events that result in unsolved phylogenies including polytomies and reticulate evolutionary patterns. Next-generation sequencing technologies allow access to genomic data and strongly supported phylogenies, yet biased topologies may be obtained due to insufficient taxon sampling. We analyze the hypothesis that intraspecific plastome diversity reflects biogeographic history and hybridization cycles among taxa. We generated 12 new plastome sequences covering distinct latitudinal locations of all species of subgenus Nothofagus from North Patagonia. Chloroplast genomes were assembled, annotated, and searched for simple sequence repeats (SSRs). Phylogenetic reconstructions included species and sampled locations. The six Nothofagus species analyzed were of similar size and structure; only Nothofagus obliqua of subgenus Lophozonia, used as an outgroup, presented slight differences in size. We detected a variable number of SSRs in distinct species and locations. Phylogenetic analyses of plastomes confirmed that subgenus Nothofagus organizes into two monophyletic clades each consisting of individuals of different species. We detected a geographic structure within subgenus Nothofagus and found evidence of local chloroplast sharing due to past hybridization, followed by adaptive introgression and ecological divergence. These contributions enrich the comprehension of transversal evolutionary mechanisms such as chloroplast capture and its implications for phylogenetic and phylogenomic analyses.

The complete plastome of Thalictrum elegans Wall. ex Royle and its phylogenetic analysis

Thalictrum elegans Wall. ex Royle, a species within the family Ranunculaceae, is mainly distributed along forest margins and grassy slopes at altitudes 2700-4000 m on the Qinghai-Tibetan Plateau. Despite its wide distribution in alpine ecosystems, its genetic diversity remains poorly understood. In this study, we assembled and characterized the complete chloroplast genome of T. elegans, addressing a significant gap in our understanding of its genetic composition. The chloroplast genome is 155,864 base pairs long and contains 131 genes, including 86 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis of 15 representative Thalictrum species revealed that the genus can be classified into three clades. T. elegans along with another nine other species formed the largest monophyletic clade and is most closely related to T. petaloideum and T. foliosum. These findings enhance our understanding of the genetic diversity of T. elegans and contribute to its conservation and utilization.

Yushaniadezhui (Poaceae, Bambusoideae), a new bamboo species from Yunnan, China

A new bamboo species, Yushaniadezhui, from Kunming, Yunnan, China is described and illustrated in this paper. The new species used to be misidentified as Y.polytricha. Based on careful comparison of morphological features and molecular phylogeny evidence, we confirmed its identity as a new member of the genus Yushania. Yushaniadezhui resembles Y.maculata, Y.polytricha and Y.weixiensis in several aspects, such as culm height and branch complement structure. However, the glabrous culm leaf sheaths and internodes, the absence of auricles and oral setae on most foliage leaves, except the one-year-old foliage leaves, the pubescence on the adaxial surface of the one-year-old foliage leaves and its limestone habitat preference can readily distinguish this new species from its related taxa. Moreover, we emphasise that individuals from various populations and molecular markers with different inheritance patterns for phylogeny reconstruction should be included in new species discovery, especially in plant groups with complex evolutionary histories.

The complete chloroplast genome sequence and phylogenetic analysis of Tragopogon pratensis L. (Asteraceae)

Currently, the phylogenetic relationships of Tragopogon pratensis Linnaeus (1753) remain unclear. This study presents the first report on the complete chloroplast genome of T. pratensis, which is a quadripartite structure with a length of 153,002 bp and containing a large single copy (LSC, 84,225 bp) region, a small single copy (SSC, 18,407 bp) region, a pair of inverted repeats (IR, 25,185 bp) regions. A total of 134 genes are identified, including 87 protein-coding genes, 8 rRNA genes, 37 tRNA genes, and 2 pseudogenes. Phylogenetic analysis revealed that T. pratensis is most closely related to T. dubius and that Tragopogon is a monophyletic genus.

Analysis of the complete mitochondrial genome of Panax quinquefolius reveals shifts from cis-splicing to trans-splicing of intron cox2i373

Panax quinquefolius is a perennial plant with medicinal values. In this study, we assembled the complete mitochondrial genome (mitogenome) of P. quinquefolius using PMAT assembler. The total length of P. quinquefolius mitogenome is 573,154 bp. We annotated a total of 34 protein-coding genes (PCGs), 35 tRNA genes, and 6 rRNA genes in this mitogenome. The analysis of repetitive elements shows that there are 153 SSRs, 24 tandem repeats and 242 pairs of dispersed repeats this mitogenome. Also, we found 24 homologous sequences with a total length of 64,070 bp among its mitogenome and plastome, accounting for 41.05 % of the plastome, and 11.18 % of the mitogenome, showing a remarkable frequent sequence dialogue between plastome and mitogenomes. Besides, a total of 583 C to U RNA editing sites on 34 PCGs of high confidence were predicted by using Deepred-mt. We also inferred the phylogenetic relationships of P. quinquefolius and other angiosperms based on mitochondrial PCGs. Finally, we observed a shift from cis- to trans-splicing in P. quinquefolius for two mitochondrial introns, namely cox2i373 and nad1i728, and a pair of 48 bp short repetitive sequences may be associated with the breaking and rearrangement of the cox2i373 intron. The fragmentation of the cox2i373 intron was further confirmed by our PCR amplification experiments. In summary, our report on the P. quinquefolius mitogenome provides a new perspective on the intron evolution of the mitogenome.

The complete chloroplast genome of Swertia davidii (gentianaceae) and its phylogenetic analysis

To elucidate the genetic information and evolutionary relationships of Swertia, we initiated the sequencing of the complete chloroplast genome of Swertia davidii Franch. 1888, complemented by comparative analyses with closely related species. The chloroplast genome of S. davidii was 153,516 bp in length and exhibited a typical quadripartite structure. It contained two regions with Inverted Repeat lengths of 25,767 bp, located between one Large Single-Copy region (83,617 bp) and one Short Single-Copy region (18,365 bp). The chloroplast genome of S. davidii encoded 132 genes, including 87 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The overall GC content was 38.15%. Maximum likelihood phylogenetic analysis of Swertia based on 26 available plastomes showed a close relationship between S. davidii and S. kouitchensi. This study will contribute to the genetic preservation of the species and the phylogenetic study of Swertia.

The complete chloroplast genome of rhododendron williamsianum (ericaceae)

Rhododendron williamsianum Rehder & E. H. Wilson 1913, is a plant with important horticultural value. Here we report its chloroplast genome. The total length of the chloroplast genome was 205,424 bp, with a GC content of 35.8%. It consisted of a 107,968 bp large single copy, a 2606 bp small single copy, and a pair of 47,425 bp inverted repeats separating them. Within the chloroplast genome, there were a total of 110 unique genes, which included 76 protein-coding genes, 4 rRNA genes, and 30 tRNA genes. Our phylogenetic analyses indicated that R. williamsianum was closely genetically related to R. sutchuenense and R. jingangshanicum. The findings from this study not only contribute to the genetic database of Rhododendron plants but also have implications for evolutionary research within the family Ericaceae.

Chloroplast genomes of Eriobotrya elliptica and an unknown wild loquat "YN-1"

The chloroplast genomes of wild loquat can help to determine their place in the history of evolution. Here, we sequenced and assembled two novel wild loquat's chloroplast genomes, one is Eriobotrya elliptica, and the other is an unidentified wild loquat, which we named "YN-1". Their sizes are 159,471 bp and 159,399 bp, respectively. We also assembled a cultivated loquat named 'JFZ', its chloroplast genome size is 159,156 bp. A comparative study was conducted with six distinct species of loquats, including five wild loquats and one cultivated loquat. The results showed that both E. elliptica and "YN-1" have 127 genes, one gene more than E. fragrans, which is psbK. Regions trnF-GAA-ndhJ, petG-trnP-UGG, and rpl32-trnL-UAG were found to exhibit high variability. It was discovered that there was a positive selection on rpl22 and rps12. RNA editing analysis found several chilling stress-specific RNA editing sites, especially in rpl2 gene. Phylogenetic analysis results showed that "YN-1" is closely related to E. elliptica, E. obovata and E. henryi.

The complete chloroplast genome of Lindernia crustacea (L.) F. Muell 1882 (Linderniaceae) and its phylogenetic analysis

Lindernia crustacea (L.) F. Muell 1882, a species in the Linderniaceae family, holds traditional medicinal value in China. To investigate its genetic diversity, we assembled, annotated, and characterized the first complete chloroplast genome of L. crustacea using Illumina sequencing data and various bioinformatics tools. The genome is 153,647 bp in length, with a GC content of 37.6%. It exhibits a typical quadripartite structure, consisting of a large single-copy region (LSC) of 85,411 bp, a small single-copy region (SSC) of 18,724 bp, and two inverted repeat sequences (IRa and IRb) of 25,816 bp each. The genome was predicted to contain 131 genes, including 87 protein-coding genes, 36 tRNA genes, and eight rRNA genes. Phylogenomic analysis indicated that L. crustacea is closely related to L. stricta. These findings provide a foundation for further research on the evolution and potential medicinal applications of the Linderniaceae family.

The complete chloroplast genome of Gardenia stenophylla Merr (Rubiaceae) and its phylogenetic analysis

Gardenia stenophylla Merr, a member of the genus Gardenia in the family Rubiaceae, possesses significant medicinal and ornamental value and is widely distributed in China. This study reports the newly sequenced chloroplast genome of Gardenia stenophylla Merr. The complete chloroplast genome of Gardenia stenophylla Merr (155,109 bp, GC content of 37.5%) was shown to have a typical quadripartite structure, containing a pair of inverted repeat regions (IRs) of 28,802 bp separated by a large single-copy (LSC) region of 85,396 bp and a small single-copy (SSC) region of 18,109 bp. The chloroplast genome contained 151 genes encoding 106 proteins, 37 tRNAs, and eight rRNAs. The Gardenia stenophylla Merr chloroplast genome displayed the closest phylogenetic relationship to Gardenia jasminoides and Gardenia jasminoides var. grandiflora. These data will assist in future molecular phylogenetics of the Rubiaceae.

The de novo assembly and characterization of the complete mitochondrial genome of bottle gourd (Lagenaria siceraria) reveals the presence of homologous conformations produced by repeat-mediated recombination

Introduction

Bottle gourd is an annual herbaceous plant that not only has high nutritional value and many medicinal applications but is also used as a rootstock for the grafting of cucurbit crops such as watermelon, cucumber and melon. Organellar genomes provide valuable resources for genetic breeding.

Methods

A hybrid strategy with Illumina and Oxford Nanopore Technology sequencing data was used to assemble bottle gourd mitochondrial and chloroplast genomes.

Results

The length of the bottle gourd mitochondrial genome was 357547 bp, and that of the chloroplast genome was 157121 bp. These genomes had 27 homologous fragments, accounting for 6.50% of the total length of the bottle gourd mitochondrial genome. In the mitochondrial genome, 101 simple sequence repeats (SSRs) and 10 tandem repeats were identified. Moreover, 1 pair of repeats was shown to mediate homologous recombination into 1 major conformation and 1 minor conformation. The existence of these conformations was verified via PCR amplification and Sanger sequencing. Evolutionary analysis revealed that the mitochondrial genome sequence of bottle gourd was highly conserved. Furthermore, collinearity analysis revealed many rearrangements between the homologous fragments of Cucurbita and its relatives. The Ka/Ks values for most genes were between 0.3~0.9, which means that most of the genes in the bottle gourd mitochondrial genome are under purifying selection. We also identified a total of 589 potential RNA editing sites on 38 mitochondrial protein-coding genes (PCGs) on the basis of long noncoding RNA (lncRNA)-seq data. The RNA editing sites of nad1-2, nad4L-2, atp6-718, atp9-223 and rps10-391 were successfully verified via PCR amplification and Sanger sequencing.

Conclusion

In conclusion, we assembled and annotated bottle gourd mitochondrial and chloroplast genomes to provide a theoretical basis for similar organelle genomic studies.

The complete chloroplast genome of Taraxacum albidum (Asteraceae), a Japanese endemic dandelion

Taraxacum albidum, a perennial herb of the Asteraceae family, exhibits both tetraploid and pentaploid in Japan. This study sequenced and characterized the complete chloroplast genome of T. albidum, revealing a 151,451 bp sequence with a typical quadripartite structure, comprising one large single-copy (LSC) region of 84,052 bp, one small single-copy (SSC) region of 18,541 bp, and two inverted repeat (IR) regions, IRa and IRb, each 24,429 bp in length. The chloroplast genome, excluding duplicates, contained 113 unique genes, including 79 protein-coding genes, 30 transfer RNA genes, and four ribosomal RNA genes. The GC content of this genome was 37.7%. Phylogenetic analysis revealed that T. albidum is most closely related to T. mongolicum, with the chloroplast genome sequences being nearly identical, differing by only one nucleotide. These findings suggest that the maternal lineage of T. albidum likely originates from T. mongolicum or its closely related species.

The complete chloroplast genome of Flemingia stricta Roxb. ex Ait. 1812 (Phaseoleae, Fabaceae)

Flemingia stricta Roxb. ex Ait. 1812 belongs to the Phaseoleae tribe within the Fabaceae family and has significant pharmaceutical value. In this study, we reported the complete chloroplast genome of F. stricta using the Illumina DNA sequencing data. The chloroplast genome was 152,940 bp and encoded 111 unique genes, including 77 protein-coding genes (PCGs), 30 transfer RNA (tRNA) genes, and 4 ribosomal RNA (rRNA) genes. The phylogenetic analysis confirmed that F. stricta was closely related to Flemingia prostrata and Flemingia macrophylla. The chloroplast genome of F. stricta could provide critical information for the molecular breeding of F. stricta and be used as a reference genome for other species of Phaseoleae.

The plastome and phylogenetic status of Cotoneaster rosiflorus (Rosaceae)

Endemic to Taiwan Province, China, Cotoneaster rosiflorus Kun-Cheng Chang & Fu-Yuan Lu 2011 (Rosaceae) holds significant ecological and ornamental importance. Despite its value, research on its molecular data and phylogenetic position has remained limited. In this study, we addressed this gap by sequencing the genome-skimming data, assembling its plastome, and investigating its phylogenetic position. The plastome, spanning 159,449 bp in length, consisted of a large single-copy (87,433 bp), a small single-copy (19,262 bp), and two inverted repeat regions (26,377 bp). We annotated a total of 128 functional genes, including 84 protein-coding genes, 36 transfer genes, and eight ribosomal RNA genes. The phylogenetic results indicated that C. rosiflorus is closely related to C. dammerii, suggesting that C. rosiflorus might have captured its chloroplast from C. dammerii through hybridization and introgression events. This study offered valuable insights for forthcoming phylogenetic and population genetic investigations of Cotoneaster.

Characterization of the complete chloroplast genome of Rhodiola sachalinensis and comparative analysis with its congeneric plants

Rhodiola, belonging to the Crassulaceae family, is a perennial herbaceous plant genus. There are about 90 Rhodiola species worldwide, some of which have been reported to have medicinal properties. Rhodiola sachalinensis is a perennial medicinal herb within this genus and, in the present study, its chloroplast genome was sequenced, assembled, annotated and compared with 24 other Rhodiola species. The results obtained show that the chloroplast genome of R. sachalinensis is 151 595 bp long and has a CG content of 37.7%. The inverted repeats (IR) region of the Rhodiola chloroplast genome is the most conserved region, with the main differences being observed in the ycf1 and ndhF genes at the IRb-small single copy boundary, and rps19 and trnH genes at the IRa-large single copy boundary. Phylogenetic analysis showed that Rhodiola species form two major clades, and species with recorded medicinal properties, clustered together in one branch except for R. dumulosa. Within the genus, R. sachalinensis is most closely related to Rhodiola rosea, although comparative analyses showed that only R. sachalinensis and Rhodiola subopposita contained the psbZ gene, which encodes a highly conserved protein subunit of the Photosystem II core complex. Overall, the present study contributes to the understanding of the chloroplast genome of Rhodiola species, and provides a theoretical basis for the study of their genetic diversity and possible use as medicinal plants.

Comparative analysis the chloroplast genomes of Celastrus (Celastraceae) species: Provide insights into molecular evolution, species identification and phylogenetic relationships

BACKGROUND

The genus Celastrus is an important medicinal plant resource. The similarity of morphology and the lack of complete chloroplast genome analysis have significantly impeded the exploration of species identification, molecular evolution and phylogeny of Celastrus.

PURPOSE

In order to resolve the phylogenic controversy of Celastrus species, the chloroplast genome comparative analysis was performed to provide genetic evidence.

METHODS

In this study, we collected and sequenced ten chloroplast genomes of Celastrus species from China and downloaded three chloroplast genomes from the databases. The chloroplast genomes were compared and analyzed to explore their characteristics and evolution. Furthermore, the phylogenetic relationships of Celastrus species were inferred based on the whole chloroplast genomes and protein-coding genes.

RESULTS

All the 13 Celastrus species chloroplast genomes showed a typical quadripartite structure with genome sizes ranging from 155,113 to 157,366 bp. The intron loss of the rps16 gene occurred in all the 13 Celastrus species. The GC content, gene sequence, repeat types and codon bias pattern were highly conserved. Ten highly variation regions were identified, which can be used as potential DNA markers in molecular identification of Celastrus species. Eight genes, including accD, atp4, ndhB, rpoC1, rbcL, rpl2, rpl20 and ycf1, were detected to experience positive selection. Phylogenetic analysis showed that Celastrus was a monophyletic group and Tripterygium was the closest sister-group. Noteworthy, C. gemmatus Loes. and C. orbiculatus Thunb. can be discriminated using the chloroplast genome as a super barcode. The comparative and phylogenetic analysis results proposed that C. tonkinensis Pitard. was the synonym of C. hindsii Benth.

CONCLUSION

The comparative analysis of the Celastrus chloroplast genomes can provide comprehensive genetic evidence for molecular evolution, species identification and phylogenetic relationships.

The complete chloroplast genome sequence of Lemna turionifera (Araceae)

Lemna turionifera is native to North America and northern Asia, with significant potential for industrial wastewater remediation. The complete nucleotide sequence of the L. turionifera chloroplast genome (cpDNA) was determined. The cpDNA is a circular molecule of 166,606 bp and containing a pair of inverted repeats (IRs) measuting 31,663 bp each. These IRs are flanked by a small single-copy region of 13,542 bp and a large single-copy region of 89,738 bp. The chloroplast genome of L. turionifera consisted of 112 unique genes, including 78 protein-encoding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis utilizing cpDNA provided a well-supported resolution of the relationships among subfamilies within the Araceae family. Our findings indicated a close relationship between L. turionifera and a clade consisting of L. minor, L. japonica, and L. gibba. The availability of the complete chloroplast genome sequence of L. turionifera presents valuable data for future phylogenetic investigations within the Lemnaceae family.

Comparative analysis of the mitochondrial genomes of four Dendrobium species (Orchidaceae) reveals heterogeneity in structure, synteny, intercellular gene transfer, and RNA editing

The genus Dendrobium, part of the Orchidaceae family, encompasses species of significant medicinal, nutritional, and economic value. However, many Dendrobium species are threatened by environmental stresses, low seed germination rates, and overharvesting. Mitochondria generate the energy necessary for various plant life activities. Despite their importance, research on the mitochondrial genomes of Dendrobium species is currently limited. To address this gap, we performed a comprehensive genetic analysis of four Dendrobium species-D. flexicaule, D. nobile, D. officinale, and D. huoshanense-focusing on their mitochondrial and chloroplast genomes to elucidate their genetic architecture and support conservation efforts. We utilized advanced sequencing technologies, including Illumina for high-throughput sequencing and Nanopore for long-read sequencing capabilities. Our findings revealed the multichromosomal mitochondrial genome structures, with total lengths ranging from 596,506 bp to 772,523 bp. The mitochondrial genomes contained 265 functional genes, including 64-69 protein-coding genes, 23-28 tRNA genes, and 3 rRNA genes. We identified 647 simple sequence repeats (SSRs) and 352 tandem repeats, along with 440 instances of plastid-to-mitochondrial gene transfer. Additionally, we predicted 2,023 RNA editing sites within the mitochondrial protein-coding genes, predominantly characterized by cytosine-to-thymine transitions. Comparative analysis of mitochondrial DNA across the species highlighted 25 conserved genes, with evidence of positive selection in five genes: ccmFC, matR, mttB, rps2, and rps10. Phylogenetic assessments suggested a close sister relationship between D. nobile and D. huoshanense, and a similar proximity between D. officinale and D. flexicaule. This comprehensive genomic study provides a critical foundation for further exploration into the genetic mechanisms and biodiversity of Dendrobium species, contributing valuable insights for their conservation and sustainable utilization.

Polyphyly of Boehmeria (Urticaceae) congruent with plastome structural variation

Boehmeria is a taxonomically challenging group within the nettle family (Urticaceae). The polyphyly of the genus has been proposed by previous studies with respect to five genera (Debregeasia, Cypholophus, Sarcochlamys, Archiboehmeria, and Astrothalamus). Extensive homoplasy of morphological characters has made generic delimitation problematic. Previous studies in other plant groups suggest that plastome structural variations have the potential to provide characters useful in reconstructing evolutionary relationships. We aimed to test this across Boehmeria and its allied genera by mapping plastome structural variations onto a resolved strongly supported phylogeny. In doing so, we expanded the sampling of the plastome to include Cypholophus, Sarcochlamys, Archiboehmeria, and Astrothalamus for the first time. The results of our phylogenomic analyses provide strong support for Sarcochlamys as being more closely related to Leucosyke puya than to Boehmeria and for the clustering of Boehmeria s.l. into four subclades. The sizes of the plastomes in Boehmeria s.l. ranged from 142,627 bp to 170,958 bp. The plastomes recovered a typical quadripartite structure comprising 127~146 genes. We observe several obvious structural variations across the taxa such as gene loss and multiple gene duplication, inverted repeat (IR) contraction and wide expansions, and inversions. Moreover, we recover a trend for these variations that the early clades were relatively conserved in evolution, whereas the later diverging clades were variable. We propose that the structural variations documented may be linked to the adaptation of Boehmeria s.l. to a wide range of habitats, from moist broadleaf forests in Asia to xeric shrublands and deserts in Africa. This study confirms that variation in plastome gene loss/duplication, IR contraction/expansion, and inversions can provide evidence useful for the reconstruction of evolutionary relationships.

Comparative analysis of chloroplast genome and evolutionary history of Hemerocallis

Members of the genus Hemerocallis have significant value as ornamental, edible, and medicinal plants, particularly in China, where they have been utilized for thousands of years as both a vegetable and Traditional Chinese Medicine. Hemerocallis species exhibit strict control over flowering time, with individuals flowering either diurnally or nocturnally. However, our understanding of the evolutionary history of this genus, especially concerning important horticultural traits, remains limited. In this study, sequencing and assembly efforts were conducted on 73 samples within the Hemerocallis genus. All accessions were classified into two distinct groups based on their diurnal (daylilies) or nocturnal (nightlilies) flowering habits. Comparative analysis of the chloroplast genomes from these two groups identified fifteen variant hotspot regions, including fourteen SNPs and one deletion, which hold promise for the development of molecular markers for interspecific identification. Phylogenetic trees, generated through both maximum-likelihood and Bayesian inference methods using 76 shared protein-coding sequences, revealed that diurnal flowering evolved prior to nocturnal flowering. The divergence between the two groups is estimated to have occurred approximately 0.82 MYA (95% CI: 0.35-1.45 MYA). The ancestral state of Hemerocallis is hypothesized to have featured diurnal flowering with orange yellow petals. This study marks the first reconstruction of the evolutionary history and ancestral state of the genus Hemerocallis. The findings contribute significantly to our understanding of the adaptation and speciation history within the genus.

The first complete chloroplast genome of Cyclamen persicum and its phylogenetic position within Primulaceae

Cyclamen persicum Mill., 1768, is a perennial herb of Primulaceae and is native to the Mediterranean region. In this study, we sequenced the chloroplast genome of Cyclamen persicum. Its complete chloroplast contained 151,911 nucleotides, including a large single-copy (LSC) region with a length of 83,191 bp, a small single-copy (SSC) region with a length of 17,922 bp, and a pair of reverse repeat IR regions (25,399 bp). The C. persicum chloroplast genome encoded 112 unique genes, including 78 protein-coding genes, 30 tRNA genes, and four rRNA genes. The GC content of the entire genome was 37.25%, lower than that of many angiosperm plastome. The phylogenetic result indicated that C. persicum exhibited the closest relationship with Cyclamen rohlfsianum, and provided new information for the phylogeny relationship of genus Cyclamen.

De novo assembly and comprehensive analysis of the mitochondrial genome of Taxus wallichiana reveals different repeats mediate recombination to generate multiple conformations

Taxus plants are the exclusive source of paclitaxel, an anticancer drug with significant medicinal and economic value. Interspecies hybridization and gene introgression during evolution have obscured distinctions among Taxus species, complicating their phylogenetic classification. While the chloroplast genome of Taxus wallichiana, a widely distributed species in China, has been sequenced, its mitochondrial genome (mitogenome) remains uncharacterized.We sequenced and assembled the T. wallichiana mitogenome using BGI short reads and Nanopore long reads, facilitating comparisons with other gymnosperm mitogenomes. The T. wallichiana mitogenome spanning 469,949 bp, predominantly forms a circular configuration with a GC content of 50.51%, supplemented by 3 minor configurations mediated by one pair of LRs and two pairs of IntRs. It includes 32 protein-coding genes, 7 tRNA genes, and 3 rRNA genes, several of which exist in multiple copies.We detailed the mitogenome's structure, codon usage, RNA editing, and sequence migration between organelles, constructing a phylogenetic tree to elucidate evolutionary relationships. Unlike typical gymnosperm mitochondria, T. wallichiana shows no evidence of mitochondrial-plastid DNA transfer (MTPT), highlighting its unique genomic architecture. Synteny analysis indicated extensive genomic rearrangements in T. wallichiana, likely driven by recombination among abundant repetitive sequences. This study offers a high-quality T. wallichiana mitogenome, enhancing our understanding of gymnosperm mitochondrial evolution and supporting further cultivation and utilization of Taxus species.

Exploring the Evolutionary History and Phylogenetic Relationships of Giant Reed (Arundo donax) through Comprehensive Analysis of Its Chloroplast Genome

Giant reed (Arundo donax) is widely distributed across the globe and is considered an important energy crop. This study presents the first comprehensive analysis of the chloroplast genome of giant reed, revealing detailed characteristics of this species' chloroplast genome. The chloroplast genome has a total length of 137,153 bp, containing 84 protein-coding genes, 38 tRNA genes, and 8 rRNA genes, with a GC content of 39%. Functional analysis indicates that a total of 45 photosynthesis-related genes and 78 self-replication-related genes were identified, which may be closely associated with its adaptability and growth characteristics. Phylogenetic analysis confirmed that Arundo donax cv. Lvzhou No.1 belongs to the Arundionideae clade and occupies a distinct evolutionary position compared to other Arundo species. The findings of this study not only enhance our understanding of the giant reed genome but also provide valuable genetic resources for its application in biotechnology, bioenergy crop development, and ecological restoration.

Assembly and evolutionary analysis of the complete mitochondrial genome of Trichosanthes kirilowii, a traditional Chinese medicinal plant

Trichosanthes kirilowii (T. kirilowii) is a valuable plant used for both medicinal and edible purposes. It belongs to the Cucurbitaceae family. However, its phylogenetic position and relatives have been difficult to accurately determine due to the lack of mitochondrial genomic information. This limitation has been an obstacle to the potential applications of T. kirilowii in various fields. To address this issue, Illumina and Nanopore HiFi sequencing were used to assemble the mitogenome of T. kirilowii into two circular molecules with sizes of 245,700 bp and 107,049 bp, forming a unique multi-branched structure. The mitogenome contains 61 genes, including 38 protein-coding genes (PCGs), 20 tRNAs, and three rRNAs. Within the 38 PCGs of the T. kirilowii mitochondrial genome, 518 potential RNA editing sites were identified. The study also revealed the presence of 15 homologous fragments that span both the chloroplast and mitochondrial genomes. The phylogenetic analysis strongly supports that T. kirilowii belongs to the Cucurbitaceae family and is closely related to Luffa. Collinearity analysis of five Cucurbitaceae mitogenomes shows a high degree of structural variability. Interestingly, four genes, namely atp1, ccmFC, ccmFN, and matR, played significant roles in the evolution of T. kirilowii through selection pressure analysis. The comparative analysis of the T. kirilowii mitogenome not only sheds light on its functional and structural features but also provides essential information for genetic studies of the genus of Cucurbitaceae.

The complete plastome of Amaranthus roxburghianus (Amaranthaceae)

Amaranthus roxburghianus H.W. Kung 1935, belonging to the Amaranthaceae family, is recognized for its significant medicinal properties. However, molecular research on this species has been limited. This study represents the inaugural documentation of the sequencing and assembly of the complete plastome of A. roxburghianus. The genome spans a total length of 149,969 base pairs (bp), exhibiting a conventional quadripartite structure. This structure comprises a large single-copy (LSC) region of 83,917 bp, a small single-copy (SSC) region of 18,124 bp, and two inverted repeat (IR) regions, each extending to 23,964 bp. In its entirety, the A. roxburghianus plastome encompasses 128 genes, of which 107 are unique, encompassing 77 individual protein-coding genes, 26 unique tRNA genes, and four unique rRNA genes. Phylogenetic analysis has shown a close resemblance between A. roxburghianus and A. polygonoides, both part of the subgenus Albersia. Although the genus Amaranthus is roughly divided into three subgenera, additional plastid genomic data are required for a more accurate assignment of A. albus and A. blitoides. The sequencing of this plastome is a significant step forward, likely to expedite the development of molecular markers and significantly contribute to genetic assays involving this distinctive species.

The complete chloroplast genome sequences of nine melon varieties (Cucumis melo L.): lights into comparative analysis and phylogenetic relationships

Melon (Cucumis melo L.) is one of the most extensively grown horticulture crops of the world. Based on the morphological characters, melon was formerly divided into two subspecies, Cucumis melo ssp. melo and C. melo ssp. agrestis. However, the present methods are still inadequate to distinguish between them. The phylogenetic analysis based on chloroplast genome sequences could provide essential evidence for the classification of melon varieties. We sequenced the chloroplast genomes of nine different melon varieties by the Illumina Hiseq and performed bioinformatic analyses including repeat element analysis, genome comparison and phylogenetic analysis. The results showed that the melon chloroplast genome has a typical quadripartite structure that was conserved across the analyzed sequences. Its length ranges between 155, 558 and 156, 569 bp, with a total GC content varying from 36.7% to 37%. We found 127-132 genes in melon chloroplast genomes, including 85-87 protein-coding regions, 34-37 tRNA and 6-8 rRNA genes. The molecular structure, gene order, content, codon usage, long repeats, and simple sequence repeats (SSRs) were mostly conserved among the nine sequenced genomes. Phylogenetic analysis showed that the chloroplast genome could clearly distinguish between C. melo ssp. melo and C. melo ssp. agrestis. This study not only provides valuable knowledge on melon chloroplasts, but also offers a theoretical basis and technical support for the genetic breeding of melons.

Complete mitochondrial genome of Melia azedarach L., reveals two conformations generated by the repeat sequence mediated recombination

Melia azedarach is a species of enormous value of pharmaceutical industries. Although the chloroplast genome of M. azedarach has been explored, the information of mitochondrial genome (Mt genome) remains surprisingly limited. In this study, we used a hybrid assembly strategy of BGI short-reads and Nanopore long-reads to assemble the Mt genome of M. azedarach. The Mt genome of M. azedarach is characterized by two circular chromosomes with 350,142 bp and 290,387 bp in length, respectively, which encodes 35 protein-coding genes (PCGs), 23 tRNA genes, and 3 rRNA genes. A pair of direct repeats (R1 and R2) were associated with genome recombination, resulting in two conformations based on the Sanger sequencing and Oxford Nanopore sequencing. Comparative analysis identified 19 homologous fragments between Mt and chloroplast genome, with the longest fragment of 12,142 bp. The phylogenetic analysis based on PCGs were consist with the latest classification of the Angiosperm Phylogeny Group. Notably, a total of 356 potential RNA editing sites were predicted based on 35 PCGs, and the editing events lead to the formation of the stop codon in the rps10 gene and the start codons in the nad4L and atp9 genes, which were verified by PCR amplification and Sanger sequencing. Taken together, the exploration of M. azedarach gap-free Mt genome provides a new insight into the evolution research and complex mitogenome architecture.

Complete Chloroplast Genome of Megacarpaea megalocarpa and Comparative Analysis with Related Species from Brassicaceae

Megacarpaea megalocarpa, a perennial herbaceous species belonging to the Brassicaceae family, has potential medicinal value. We isolated and characterized the chloroplast (cp) genome of M. megalocarpa and compared it with closely related species. The chloroplast genome displayed a typical quadripartite structure, spanning 154,877 bp, with an overall guanine-cytosine (GC) content of 36.20%. Additionally, this genome contained 129 genes, 105 simple sequence repeats (SSRs), and 48 long repeat sequences. Significantly, the ycf1 gene exhibited a high degree of polymorphism at the small single copy (SSC) region and the inverted repeat a (IRa) boundary. Despite this polymorphism, relative synonymous codon usage (RSCU) values were found to be similar across species, and no large segment rearrangements or inversions were detected. The large single copy (LSC) and SSC regions showed higher sequence variations and nucleotide polymorphisms compared to the IR region. Thirteen distinct hotspot regions were identified as potential molecular markers. Our selection pressure analysis revealed that the protein-coding gene rpl20 is subjected to different selection pressures in various species. Phylogenetic analysis positioned M. megalocarpa within the expanded lineage II of the Brassicaceae family. The estimated divergence time suggests that M. megalocarpa diverged approximately 4.97 million years ago. In summary, this study provides crucial baseline information for the molecular identification, phylogenetic relationships, conservation efforts, and utilization of wild resources in Megacarpaea.

Plant mitochondrial genome map (PMGmap): A software tool for the comprehensive visualization of coding, noncoding and genome features of plant mitochondrial genomes

Tools for visualizing genomes are essential for investigating genomic features and their interactions. Currently, tools designed originally for animal mitogenomes and plant plastomes are used to visualize the mitogens of plants but cannot accurately display features specific to plant mitogenomes, such as nonlinear exon arrangement for genes, the prevalence of functional noncoding features and complex chromosomal architecture. To address these problems, a software package, plant mitochondrial genome map (PMGmap), was developed using the Python programming language. PMGmap can draw genes at exon levels; draw cis- and trans-splicing gene maps, noncoding features and repetitive sequences; and scale genic regions by using the scaling of the genic regions on the mitogenome (SAGM) algorithm. It can also draw multiple chromosomes simultaneously. Compared with other state-of-the-art tools, PMGmap showed better performance in visualizing 405 plant mitogenomes, showing potential as an invaluable tool for plant mitogenome research. The web and container versions and the source code of PMGmap can be accessed through the following link: http://www.1kmpg.cn/pmgmap.

Genetic diversity of food-medicinal Lycium spp. in China: Insights from chloroplast genome

Objective

Goji (fruits of Lycium spp.) is commonly consumed as food and medicine. The increasing market demand for goji has led to its wide cultivation and broad breeding, which might cause loss of genetic diversity. This study aims to uncover the genetic diversity of the cultivated and wild Lycium.

Methods

The chloroplast genome (CPG) of 34 accessions of Chinese food-medicinal Lycium spp., including the popular cultivars and their wild relatives, was re-sequenced and assembled, based on which the genetic diversity was evaluated.

Results

Sequence structural comparison shows that CPG is comparatively conserved within species. Phylogenetic analysis indicates that CPG is sufficient for the discrimination of Lycium species; combined with nuclear ribosomal internal transcribed spacer (Nr ITS) sequences, materials with mixed genetic backgrounds can be identified. Nucleotide diversity analysis reveals that the modern cultivars are probably with a common maternal parent, while the wild accessions are with higher level of genetic diversity.

Conclusion

For the first time this study reveals the intraspecies genetic diversity of Lycium spp. using CPG, highlighting the urgent conservation demand of wild genetic resources of Lycium. Our study also demonstrates that CPG provides crucial evidence for identification of Lycium species with mixed genetic backgrounds and highlights the importance of the wild relatives in genetic diversity conservation. This CPG-based technology will contribute to the sustainable development of medicinal plants broadly.

Chromosome-level genome assembly of Pedicularis kansuensis illuminates genome evolution of facultative parasitic plant

Parasitic plants have a heterotrophic lifestyle, in which they withdraw all or part of their nutrients from their host through the haustorium. Despite the release of many draft genomes of parasitic plants, the genome evolution related to the parasitism feature of facultative parasites remains largely unknown. In this study, we present a high-quality chromosomal-level genome assembly for the facultative parasite Pedicularis kansuensis (Orobanchaceae), which invades both legume and grass host species in degraded grasslands on the Qinghai-Tibet Plateau. This species has the largest genome size compared with other parasitic species, and expansions of long terminal repeat retrotransposons accounting for 62.37% of the assembly greatly contributed to the genome size expansion of this species. A total of 42,782 genes were annotated, and the patterns of gene loss in P. kansuensis differed from other parasitic species. We also found many mobile mRNAs between P. kansuensis and one of its host species, but these mobile mRNAs could not compensate for the functional losses of missing genes in P. kansuensis. In addition, we identified nine horizontal gene transfer (HGT) events from rosids and monocots, as well as one single-gene duplication events from HGT genes, which differ distinctly from that of other parasitic species. Furthermore, we found evidence for HGT through transferring genomic fragments from phylogenetically remote host species. Taken together, these findings provide genomic insights into the evolution of facultative parasites and broaden our understanding of the diversified genome evolution in parasitic plants and the molecular mechanisms of plant parasitism.

The complete chloroplast genome sequence and phylogenetic relationship analysis of Eomecon chionantha, one species unique to China

Eomecon chionantha Hance, an endemic species in China, has a long medical history in Chinese ethnic minority medicine and is known for its anti-inflammatory and analgesic effects. However, studies of E. chionantha are lacking. In this study, we investigated the characteristics of the E. chionantha chloroplast genome and determined the taxonomic position of E. chionantha in Papaveraceae via phylogenetic analysis. In addition, we determined molecular markers to identify E. chionantha at the molecular level by comparing the chloroplast genomes of E. chionantha and its closely related species. The complete chloroplast genomic information indicated that E. chionantha chloroplast DNA (178,808 bp) contains 99 protein-coding genes, 8 rRNAs, and 37 tRNAs. Meanwhile, we were able to identify a total of 54 simple sequence repeats through our analysis. Our findings from the phylogenetic analysis suggest that E. chionantha shares a close relationship with four distinct species, namely Macleaya microcarpa, Coreanomecon hylomeconoides, Hylomecon japonica, and Chelidonium majus. Additionally, using the Kimura two-parameter model, we successfully identified five hypervariable regions (ycf4-cemA, ycf3-trnS-GGA, trnC-GCA-petN, rpl32-trnL-UAG, and psbI-trnS-UGA). To the best of our knowledge, this is the first report of the complete chloroplast genome of E. chionantha, providing a scientific reference for further understanding of E. chionantha from the perspective of the chloroplast genome and establishing a solid foundation for the future identification, taxonomic determination and evolutionary analysis of this species.

The complete mitochondrial genome of Pontederia crassipes: using HiFi reads to investigate genome recombination and gene transfer from chloroplast genome

Water hyacinth (Pontederia crassipes Mart.) is a monocotyledonous aquatic plant renowned for its rapid growth, extensive proliferation, biological invasiveness, and ecological resilience to variations in pH, nutrients, and temperature. The International Union for Conservation of Nature (IUCN) has listed P. crassipes among the top 100 invasive species. However, comprehensive genomic information, particularly concerning its mitochondrial genome (mitogenome), remains surprisingly limited. In this study, the complete mitogenome of P. crassipes was analyzed using bioinformatics approaches. The mitogenome is 399,263 bp long and contains 38 protein-coding genes (PCGs), 24 tRNA genes, and 3 rRNA genes. Sequence analysis revealed that the complete mitogenome of the species contains 3,289 dispersed repeats, and 765 RNA editing sites in protein-coding genes. The P. crassipes mitogenome possessed un-conserved structures, including extensive sequence transfer between its chloroplasts and mitochondria. Our study on the mitogenome of P. crassipes offers critical insights into its evolutionary patterns and phylogenetic relationships with related taxa. This research enhances our understanding of this invasive species, known for its significant biomass and rapid overgrowth in aquatic environments.

The complete chloroplast genome of the Syzygium buxifolium Hook. Et Arn.1833 and its phylogenetic analysis

Syzygium buxifolium. Hook. Et Arn.1833 is a member of the Myrtaceae family. This species is used in traditional Chinese medicines. It possesses numerous synonyms, reflecting the ambiguity in its taxonomy. The chloroplast genome has been widely used for species identification and phylogenetic analysis. Regrettably, there is a lack of information regarding the chloroplast genome of S. buxifolium. Here, we intend to obtain the chloroplast genome of S. buxifolium to resolve its classification problems. In particular, we utilized Illumina sequencing technology to sequence, GetOrganelle to assemble, and CPGAVAS2 to characterize the chloroplast genome of S. buxifolium. The chloroplast genome of S. buxifolium had a length of 158,581 bp and consisted of 111 unique genes, comprising 78 protein-coding genes, 29 transfer RNA (tRNA) genes, and four ribosomal RNA (rRNA) genes. In addition, we identified 86 Simple Sequence Repeats, 345 tandem repetitive sequences, and 34 dispersed repetitive sequences using modules implemented in CPGAVAS2. Lastly, we carried out phylogenetic analysis using Phylosuite. The results indicated a close relationship between S. buxifolium and S. grijsii. This study offers novel genetic data for the molecular identification and subsequent phylogenetic analysis of the Syzygium genus.

Molecular and morphological evidence supports the resurrection of Chrysospleniumguangxiense H.G.Ye & Gui C.Zhang (Saxifragaceae)

Chrysospleniumguangxiense H.G.Ye & Gui C.Zhang was first described as a new species in 1994 but later synonymized in the Flora of China treatment with C.glossophyllum H.Hara. Plastid genomes and nrDNA sequences were used to infer the phylogenetic relationships of selected taxa in Chrysosplenium. Our phylogenetic analyses revealed that C.guangxiense belongs to sect. Alternifolia, is closely related to Chrysospleniumhydrocotylifolium H.Lév. & Vaniot but distant from C.glossophyllum. Morphologically, C.guangxiense could be easily distinguished from C.glossophyllum by having robust rhizomes, basal leaves with a long cuneate base and fewer teeth in the margin, curled sepal margins, and red, larger seeds. It could also be easily distinguished from C.hydrocotylifolium by possessing long elliptic leaves and a long cuneate leaf base. Along with the phylogenetic studies, the complete plastid genome of C.guangxiense was also reported. The plastid genome was 154,004 bp in length and comprised two inverted repeats (IRs) of 28,120 bp, separated by a large single-copy of 80,646 bp and a small single-copy of 17,118 bp. A total of 111 functional genes were discovered, comprising 78 protein-coding genes, 29 tRNA genes, and four rRNA genes. Based on assessment of morphological and molecular data Chrysospleniumguangxiense H.G.Ye & Gui C.Zhang is resurrected from C.glossophyllum H.Hara at species level. A global conservation assessment classifies C.guangxiense as Vulnerable (VU).

Genetic characterization and phylogenetic analysis of the Nigella sativa (black seed) plastome

In this study, the complete plastome sequence of Nigella sativa (black seed), was analyzed for the first time. The plastome spans approximately 154,120 bp, comprising four sections: the Large Single-Copy (LSC) (85,538 bp), the Small Single-Copy (SSC) (17,984 bp), and two Inverted Repeat (IR) regions (25,299 bp). A comparative study of N. sativa's plastome with ten other species from various genera in the Ranunculaceae family reveals substantial structural variations. The contraction of the inverted repeat region in N. sativa influences the boundaries of single-copy regions, resulting in a shorter plastome size than other species. When comparing the plastome of N. sativa with those of its related species, significant divergence is observed, particularly except for N. damascena. Among these, the plastome of A. glaucifolium displays the highest average pairwise sequence divergence (0.2851) with N. sativa, followed by A. raddeana (0.2290) and A. coerulea (0.1222). Furthermore, the study identified 12 distinct hotspot regions characterized by elevated Pi values (> 0.1). These regions include trnH-GUG-psbA, matK-trnQ-UUG, psbK-trnR-UCU, atpF-atpI, rpoB-psbD, ycf3-ndhJ, ndhC-cemA, petA-psaJ, trnN-GUU-ndhF, trnV-GAC-rps12, ycf2-trnI-CAU, and ndhA-ycf1. Approximately, 24 tandem and 48 palindromic and forward repeats were detected in N. sativa plastome. The analysis revealed 32 microsatellites with the majority being mononucleotide repeats. In the N. sativa plastome, phenylalanine had the highest number of codons (1982 codons), while alanine was the least common amino acid with 260 codons. A phylogenetic tree, constructed using protein-coding genes, revealed a distinct monophyletic clade comprising N. sativa and N. damascene, closely aligned with the Cimicifugeae tribe and exhibiting robust support. This plastome provides valuable genetic information for precise species identification, phylogenetic resolution, and evolutionary studies of N. sativa.

The complete chloroplast genome of the first registered Paeonia Itoh hybrid cv. Hexie in China

The first registered Paeonia Itoh hybrid cv. Hexie in China is a naturally occurring intersectional hybrid of Sect. Paeonia and Sect. Moutan. In this study, we sequenced, assembled, and analyzed the complete chloroplast genome of Paeonia Itoh hybrid cv. Hexie. The result showed that the chloroplast genome of Hexie, with a typical circular tetrad structure, is 152,958 bp in length, comprising a large single copy (LSC) region of 84,613 bp, a small single copy (SSC) region of 17,051 bp, and two reverse complementary sequences (IRs) of 25,647 bp. The chloroplast genome encoded 116 genes, including 80 protein-coding genes, 32 tRNA genes, and 4 rRNA genes. Phylogenetic analysis inferred from the shared protein-coding genes showed that the Paeonia Itoh hybrid cv. Hexie had the closest phylogenetic relationship with P. suffruticosa, followed by P. ostii, indicating that P. suffruticosa was its maternal parent. This study provides a molecular resource for phylogenetic and maternal parent studies of Paeonia Itoh hybrid, contributing to a basis for Paeonia Itoh hybrid breeding strategies in the future.

Comparative chloroplast genomes study of five officinal Ardisia Species: Unraveling interspecific diversity and evolutionary insights in Ardisia

Ardisia S.W. (Primulaceae), naturally distributed in tropical and subtropical regions, has edible and medicinal values and is prevalent in clinical and daily use in China. More genetic information for distinct species delineation is needed to support the development and utilization of the genus Ardisia. We sequenced, annotated, and compared the chloroplast genomes of five Ardisia species: A. brunnescens, A. pusilla, A. squamulosa, A. crenata, and A. brevicaulis in this study. We found a typical quadripartite structure in all five chloroplast genomes, with lengths ranging from 155,045 to 156,943 bp. Except for A. pusilla, which lacked the ycf15 gene, the other four Ardisia species contained 114 unique genes, including 79 protein-coding genes, 30 tRNAs, and four rRNAs. In addition, the rps19 pseudogene gene was present only in A. brunnescens. Five highly variable DNA barcodes were identified for five Ardisia species, including trnT-GGU-psbD, trnT-UGU-trnL-UAA, rps4-trnT-UGU, rpl32-trnL-UAG, and rpoB-trnC-GAA. The RNA editiing sites of protein-coding genes in the five Ardisia plastome were characterized and compared, and 274 (A. crenata)-288 (A. brevicaulis) were found. The results of the phylogenetic analysis were consistent with the morphological classification. Sequence alignment and phylogenetic analysis showed that ycf15 genes were highly divergent in Primulaceae. Reconstructions of ancestral character states indicated that leaf margin morphology is critical for classifying the genus Ardisia, with a rodent-like character being the most primitive. These results provide valuable information on the taxonomy and evolution of Ardisia plants.

The complete chloroplast genome sequence of Ampelopsis delavayana Planchon. ex Franch 1886 (Vitaceae)

Ampelopsis delavayana Planchon. ex Franch 1886 is a plant with significant pharmacological effects and ornamental importance. This research unveiled the complete chloroplast (cp) genome sequence of A. delavayana. The study highlights that the cp genome of A. delavayana possesses a distinct tetrameric structure spanning 162,497 base pairs, comprising a small single-copy (SSC) region of 18,902 base pairs, a large single-copy (LSC) region of 90,441 base pairs, and two inverted-repeat regions (IRs), each 26,577 base pairs in length. The GC content of the SSC, LSC, and IR regions of the genome was 31.80%, 35.16%, and 42.82%, respectively, culminating in an overall GC content of 37.27%. The genome comprised 130 genes, which included eight rRNAs, 36 tRNAs, and 86 protein-coding genes. Through phylogenetic analysis utilizing the maximum-likelihood method, it was established that A. delavayana was closely related to Ampelopsis glandulosa var. brevipedunculata, positioning it as a sister species. This report not only provides a scientific reference for understanding the phylogeny of the family Vitaceae but also enriches our genetic information of Ampelopsis.

Characterization of the complete chloroplast genome sequence of Bassia scoparia (L.) A. J. Scott 1978 (Amaranthaceae) and its phylogenetic analysis

Bassia scoparia, an annual potherb belonging to the family Amaranthaceae, has been widely used in traditional Chinese and Japanese medicine for over 2000 years. Herein, we presented its complete chloroplast. The chloroplast genome sequence was 151,278 bp in length with a 36.6% content of GC. The genome showed the typical quadripartite structure, comprising a pair of inverted repeat (IR) regions (24,353 bp) separated by a large single-copy (LSC) region (84,067 bp) and a small single-copy (SSC) region (18,505 bp). This chloroplast genome harbored 133 predicted genes, including 88 protein-coding genes, 37 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. The phylogenetic analysis indicated that B. scoparia was closely related to B. littorea. This newly sequenced chloroplast genome not only enhances our understanding of the genome of Bassia but also provides valuable insights for the evolutionary study of the family Amaranthaceae.

The complete chloroplast genome of Meconopsis torquata (Papaveraceae), a traditional Tibetan medicine

Meconopsis torquata Prain 1906, a national second-class rare and endangered plant, is reported here for the first time for its complete chloroplast genome. The genome is 153,290 bp in length, comprising a large single-copy region (LSC, 83,918 bp), a small single-copy region (SSC, 17,740 bp), and two inverted repeat sequences (IRa and IRb, each 25,816 bp). The overall GC content is 38.7%, with the IR region having the highest content (43.1%). The genome is annotated with 112 unique genes, including 4 rRNA genes, 29 tRNA genes, and 79 protein-coding genes. Analysis of codon usage bias reveals that codons ending in A/T account for 96.7% of those with a Relative Synonymous Codon Usage (RSCU) value above 1. This predominance of A/T-ending codons might be indicative of M. torquata adaptation to high-altitude environments. Phylogenetic analysis reveals a close kinship between M. torquata and M. pinnatifolia and M. paniculata, indicating that the ancestral groups of these species might have a complex evolutionary history. This study uncovers the genetic characteristics and adaptive evolution of M. torquata, offering a new perspective in understanding the phylogenetic relationships within the genus. The findings not only provide a solid theoretical foundation for the conservation and sustainable use of this rare and endangered species but also offer significant scientific support for the conservation of biodiversity.

The complete chloroplast genome sequence of Olea dioica Roxb, 1820 (Oleaceae)

Olea dioica Roxb, 1820 is a very important ethnomedicinal tree because of its medicinal properties and it belongs to the Oleaceae family. It is mainly distributed in evergreen and semi-evergreen forests. However, the chloroplast genome of O. dioica has not yet been reported. In this study, the chloroplast genome sequence of O. dioica was sequenced using next-generation sequencing technologies. The complete chloroplast genome of O. dioica was 155,138 bp in length (GenBank accession no. PP048999), comprising a large single-copy (LSC) region of 86,048 bp, a small single-copy (SSC) region of 17,816 bp, and two inverted repeat (IR) regions 25,637 bp each. The overall GC content was 37.8%. The complete chloroplast genome of O. dioica contains 131 complete genes, which are 88 protein-coding genes, 35 transfer RNA genes, and eight ribosomal RNA genes. A maximum-likelihood (ML) tree of O. dioica and 14 other species in the family Oleaceae suggested that O. dioica showed a close relationship with Olea brachiata.

The chloroplast genome of Chrozophora sabulosa Kar. & Kir. and its exploration in the evolutionary position uncertainty of genus Chrozophora

Chrozophora sabulosa Kar. & Kir. is a biennial herbaceous plant that belongs to the Euphorbiaceae family and has medicinal properties. This research aimed to identify the genetic characteristics and phylogenetic position of the Chrozophora genus within the Euphorbiaceae family. The evolutionary position of the Chrozophora genus was previously unknown due to insufficient research. Therefore, to determine the evolutionary link between C. sabulosa and other related species, we conducted a study using the NGS Illumina platform to sequence the C. sabulosa chloroplast (cp.) genome. The study results showed that the genome was 156,488 bp in length. It had a quadripartite structure consisting of two inverted repeats (IRb and IRa) of 24,649-bp, separated by an 87,696-bp LSC region and a 19,494-bp SSC region. The CP genome contained 113 unique genes, including four rRNA genes, 30 tRNA genes, and 79 CDS genes. In the second copy of the inverted repeat, there were 18 duplicated genes. The C. sabulosa lacks the petD, petB, rpl2, and rps16 intron. The analysis of simple sequence repeats (SSRs) revealed 93 SSR loci of 22 types and 78 oligonucleotide repeats of four kinds. The phylogenetic investigation showed that the Chrozophora genus evolved paraphyletically from other members of the Euphorbiaceae family. To support the phylogenetic findings, we selected species from the Euphorbiaceae and Phyllanthaceae families to compare with C. sabulosa for Ks and Ka substitution rates, InDels investigation, IR contraction and expansion, and SNPs analysis. The results of these comparative studies align with the phylogenetic findings. We identified six highly polymorphic regions shared by both families, which could be used as molecular identifiers for the Chrozophora genus (rpl33-rps18, rps18-rpl20, rps15-ycf1, ndhG-ndhI, psaI-ycf4, petA-psbJ). The cp. genome sequence of C. sabulosa reveals the evolution of plastid sequences in Chrozophora species. This is the first time the cp. genome of a Chrozophora genus has been sequenced, serving as a foundation for future sequencing of other species within the Chrozophoreae tribe and facilitating in-depth taxonomic research. The results of this research will also aid in identifying new Chrozophora species.

Structure, gene composition, divergence time and phylogeny analysis of the woody desert species Neltuma alba, Neltuma chilensis and Strombocarpa strombulifera

Neltuma alba (Algarrobo blanco), Neltuma chilensis (Algarrobo Chileno) and Strombocarpa strombulifera (Fortuna) are some of the few drought resistant trees and shrubs found in small highly fragmented populations, throughout the Atacama Desert. We reconstructed their plastid genomes using de novo assembly of paired-end reads from total genomic DNA. We found that the complete plastid genomes of N. alba and N. chilensis are larger in size compared to species of the Strombocarpa genus. The Strombocarpa species presented slightly more GC content than the Neltuma species. Therefore, we assume that Strombocarpa species have been exposed to stronger natural selection than Neltuma species. We observed high variation values in the number of cpSSRs (chloroplast simple sequence repeats) and repeated elements among Neltuma and Strombocarpa species. The p-distance results showed a low evolutionary divergence within the genus Neltuma, whereas a high evolutionary divergence was observed between Strombocarpa species. The molecular divergence time found in Neltuma and Strombocarpa show that these genera diverged in the late Oligocene. With this study we provide valuable information about tree species that provide important ecosystem services in hostile environments which can be used to determine these species in the geographically isolated communities, and keep the highly fragmented populations genetically healthy.

Comparative and phylogenetic analysis of chloroplast genomes from four species in Quercus section Cyclobalanopsis

The Quercus L. species is widely recognized as a significant group in the broad-leaved evergreen forests of tropical and subtropical East Asia. These plants hold immense economic value for their use as firewood, furniture, and street trees. However, the identification of Quercus species is considered challenging, and the relationships between these species remain unclear. In this study, we sequenced and assembled the chloroplast (cp.) genomes of four Quercus section Cyclobalanopsis species (Quercus disciformis, Quercus dinghuensis, Quercus blackei, and Quercus hui). Additionally, we retrieved six published cp. genome sequences of Cyclobalanopsis species (Quercus fleuryi, Quercus pachyloma, Quercus ningangensis, Quercus litseoides, Quercus gilva, and Quercus myrsinifolia). Our aim was to perform comparative genomics and phylogenetic analyses of the cp. whole genome sequences of ten Quercus section Cyclobalanopsis species. The results revealed that: (1) Quercus species exhibit a typical tetrad structure, with the cp. genome lengths of the newly sequenced species (Q. disciformis, Q. dinghuensis, Q. blakei, and Q. hui) being 160,805 bp, 160,801 bp, 160,787 bp, and 160,806 bp, respectively; (2) 469 SSRs were detected, among which A/T base repeats were the most common; (3) no rearrangements or inversions were detected within the chloroplast genomes. Genes with high nucleotide polymorphism, such as rps14-psaB, ndhJ-ndhK, rbcL-accD, and rps19-rpl2_2, provided potential reference loci for molecular identification within the Cyclobalanopsis section; (4) phylogenetic analysis showed that the four sections of Cyclobalanopsis were grouped into sister taxa, with Q. hui being the first to diverge from the evolutionary branch and Q. disciformis being the most closely related to Q. blackei. The results of this study form the basis for future studies on taxonomy and phylogenetics.

Mitochondrial genome complexity in Stemona sessilifolia: nanopore sequencing reveals chloroplast gene transfer and DNA rearrangements

Mitochondria are semi-autonomous organelles in eukaryotic cells with their own genome. Plant mitogenomes differ from animal mitogenomes in size, structure, and repetitive DNA sequences. Despite larger sizes, plant mitogenomes do not have significantly more genes. They exhibit diverse structures due to variations in size, repetitive DNA, recombination frequencies, low gene densities, and reduced nucleotide substitution rates. In this study, we analyzed the mitochondrial genome of Stemona sessilifolia using Nanopore and Illumina sequencing. De-novo assembly and annotation were conducted using Unicycler, Geseq, tRNAscan-SE and BLASTN, followed by codon usage, repeat sequence, RNA-editing, synteny, and phylogenetic analyses. S. sessilifolia's mitogenome consisted of one linear contig and six circular contigs totaling 724,751 bp. It had 39 protein-coding genes, 27 tRNA genes, and 3 rRNA genes. Transfer of chloroplast sequences accounted for 13.14% of the mitogenome. Various analyses provided insights into genetic characteristics, evolutionary dynamics, and phylogenetic placement. Further investigations can explore transferred genes' functions and RNA-editing's role in mitochondrial gene expression in S. sessilifolia.

Is RNA editing truly absent in the complex thalloid liverworts (Marchantiopsida)? Evidence of extensive RNA editing from Cyathodium cavernarum

RNA editing is a crucial modification in plants' organellar transcripts that converts cytidine to uridine (C-to-U; and sometimes uridine to cytidine) in RNA molecules. This post-transcriptional process is controlled by the PLS-class protein with a DYW domain, which belongs to the pentatricopeptide repeat (PPR) protein family. RNA editing is widespread in land plants; however, complex thalloid liverworts (Marchantiopsida) are the only group reported to lack both RNA editing and DYW-PPR protein. The liverwort Cyathodium cavernarum (Marchantiopsida, Cyathodiaceae), typically found in cave habitats, was newly found to have 129 C-to-U RNA editing sites in its chloroplast and 172 sites in its mitochondria. The Cyathodium genus, specifically C. cavernarum, has a large number of PPR editing factor genes, including 251 DYW-type PPR proteins. These DYW-type PPR proteins may be responsible for C-to-U RNA editing in C. cavernarum. Cyathodium cavernarum possesses both PPR DYW proteins and RNA editing. Our analysis suggests that the remarkable RNA editing capability of C. cavernarum may have been acquired alongside the emergence of DYW-type PPR editing factors. These findings provide insight into the evolutionary pattern of RNA editing in land plants.

Complete genome assembly provides a high-quality skeleton for pan-NLRome construction in melon

Melon (Cucumis melo L.), being under intensive domestication and selective breeding, displays an abundant phenotypic diversity. Wild germplasm with tolerance to stress represents an untapped genetic resource for discovery of disease-resistance genes. To comprehensively characterize resistance genes in melon, we generate a telomere-to-telomere (T2T) and gap-free genome of wild melon accession PI511890 (C. melo var. chito) with a total length of 375.0 Mb and a contig N50 of 31.24 Mb. The complete genome allows us to dissect genome architecture and identify resistance gene analogs. We construct a pan-NLRome using seven melon genomes, which include 208 variable and 18 core nucleotide-binding leucine-rich repeat receptors (NLRs). Multiple disease-related transcriptome analyses indicate that most up-regulated NLRs induced by pathogens are shell or cloud NLRs. The T2T gap-free assembly and the pan-NLRome not only serve as essential resources for genomic studies and molecular breeding of melon but also provide insights into the genome architecture and NLR diversity.

Liquid-nitrogen-free CTAB DNA extraction method from silica-dried specimens for next-generation sequencing and assembly

Next-generation sequencing requires intact and high-quality DNA. However, typical liquid-nitrogen DNA extraction methods are expensive and not practical for field sample collections. Hence, we present a cost-effective method for DNA extraction from silica-dried leaf samples, eliminating the need for liquid nitrogen. Two protocols were evaluated to determine the effectiveness of grinding dried plant samples without liquid nitrogen in comparison to the standard protocol for tissue homogenization and cell lysis. Protocol 1 involved grinding fresh leaf samples with liquid nitrogen, while Protocol 2 entailed incubating dried plant samples at-20 °C for 1 h before grinding in the absence of liquid nitrogen. Both protocols produced comparable DNA yields with an average A260/A280 ratio of 1.78±0.02, suitable for short- and long-read sequencing. Using Protocol 2, we successfully assembled ten plastomes. It also demonstrated versatility as comparable DNA quality was obtained from dried mollusks and actinomycetes, resulting in the successful assembly of two complete mitochondrial genomes. The protocol is advantageous for research workflows involving the collection of samples in the field as a long-term source of genetic material.•Drying: Fresh samples were silica-dried at silica-to-sample ratio of 2:1.•Pre-lysis: Dried samples were frozen at -20 °C for 1 hour before grinding.•Frozen samples were subjected to tissue homogenization followed by the standard CTAB DNA extraction.