Search Results (52)

The Balkan Peninsula is a biodiversity hotspot where topographic and habitat heterogeneity have shaped genetic differentiation. Polyploidization significantly contributes to diversification within plant lineages, including the allopolyploid complex of the Austrian speedwell, which comprises diploid, tetraploid and hexaploid lineages. We sampled 751 individuals from 50 populations belonging to this complex across the Balkan Peninsula and Central Europe. Diversity patterns were investigated through microsatellite markers (SSRs), plastid DNA sequences, ploidy estimations, morphological data and climatic niche differentiation analysis. Five lineages were detected within the complex according to nuclear DNA data. The plastid DNA haplotypes form two main groups that overall match those detected by SSR data and could suggest that the hexaploid lineage resulted from two different allopolyploid events. The hexaploid shows higher nuclear genetic diversity and morphological variation than its lower-ploidy relatives, which might allow the species to respond to a wider range of environmental conditions and be responsible for its success (i.e., a broader geographic range and ecological niche). Style length is a crucial character to distinguish diploids from polyploids, which may affect pollination biology within the complex. Full article

Background: Plant mitochondrial genomes exhibit extreme variation in size and structure while maintaining a conserved set of core protein-coding genes. This combination of structural diversity and functional conservation provides valuable insights into evolutionary processes such as genome expansion, rearrangement, and intracellular DNA transfer. Curcuma longa, an economically and medicinally important species in the genus Curcuma (Zingiberaceae), has not yet been studied in terms of the organization and evolution of its mitochondrial genome. Methods: In this study, we assembled and annotated the mitochondrial and plastid genomes of C. longa using third-generation HiFi sequencing data, systematically analyzing their genomic structure, repetitive sequence content, and features of sequence transfer between nuclear and organellar genomes. Results: The mitochondrial genome of C. longa was assembled as a complex, network-like structure consisting of 12 contigs with a total length of approximately 7.7 Mb, making it one of the largest mitochondrial genomes reported in monocots to date. Comparative analysis revealed significant differences in repeat types, abundance, and length distribution between the two organellar genomes. Additionally, extensive intracellular DNA transfer events were identified among the nuclear, mitochondrial, and plastid genomes. Conclusions: Overall, this study provides the first comprehensive report on the giant mitochondrial genome of C. longa, detailing its structural organization, repeat content, and intergenomic transfers. These findings lay a foundation for understanding mitochondrial genome evolution in Curcuma and offer broader insights into the mechanisms driving extreme mitochondrial genome expansion in angiosperms and monocots specifically. Full article

Background: With the advancement of the next-generation sequencing technology, it is becoming more cost-effective to obtain plastomes from genome skimming data at shallow sequencing depth. Artemisia is a species-rich genus, comprising species of great medicinal or economic value. However, plastomes of Artemisia have not been thoroughly and comparatively analyzed, and the phylogenetic relationships within the genus are still not well resolved. Methods: In this study, 19 Artemisia plastomes were obtained from genome skimming data. Together with the plastomes retrieved from the public database, comparative analyses of their structure were also conducted. We further used sequences of plastomes and nuclear internal transcribed spacer sequences to conduct phylogenetic reconstruction. Results: The Artemisia plastomes are conserved in terms of structure, GC content, gene number, and order. Some regions, i.e., accD, ccsA, ndhE, ycf1, ccsA-ndhD, trnG^GCC-trnfM^CAU, were found to be variable and could be chosen as candidates for the DNA barcode. Phylogenetic analyses also confirmed that the four subgenera of Artemisia are not monophyletic. The incongruence between plastid and nuclear phylogenies indicated that hybridization events have occurred during the evolution of the genus. Conclusions: Reconstructed phylogenies using plastome sequences and nuclear internal transcribed spacers improved our understanding of the phylogenetic backbone of Artemisia. In the future, more taxa of Artemisia should be sequenced and analyzed to clarify the evolutionary history. Full article

Clinopodium is a morphologically highly diverse and taxonomically intricate genus. Molecular studies have demonstrated high divergence within the genus, and there is no consensus on the taxonomic treatment of some groups classified as Clinopodium. The current phylogenetic understanding of the genus relies almost exclusively on the analysis of the trnK and trnL-trnF sequences. In Clinopodium s.s., there is no phylogenetic backbone based on nuclear sequences. Therefore, in this study, we included a larger number of plastid and nuclear markers to better understand the diversification of natural populations of the genus Clinopodium from the Balkans. We encompassed the wild-growing taxa from former genera that have now been integrated into Clinopodium: Calamintha, Acinos, and section Pseudomelissa from the genus Micromeria. The markers that displayed the highest informativeness in the in silico analysis were selected. Four nuclear loci (ITS1, 5.8S rDNA, ITS2, ETS) and seven plastid loci (rps16-trnK^UUU, rpl32-trnL^UAG, rps15-ycf1, psbA-trnH^GUG, rps16-trnQ^UUG, petN-psbM, psbK-trnS^UGA) were used to analyse the phylogenetic relationships between the Balkan species and subspecies currently classified into Clinopodium. Phylogenetic reconstructions showed the divergence of the two lineages with different diversification patterns. Nuclear markers have shown that the three groups within the clade Clinopodium s.s. have evolved separately, which is consistent with earlier phenetic systems. Full article

Some Melanothamnus species have been documented growing epiphytically on other algae in seaweed aquaculture farms as fouling organisms. Such turf-forming Polysiphonia-looking algae were collected from a small (<1.0 km² area) Agarophyton tenuistipitata (Gracilariaceae, Gracilariales) farm on the east coast of the Bay of Bengal and examined for their taxonomy. DNA was extracted from silica gel-preserved specimens, and plastid-encoded rbcL, nuclear-encoded small subunit SSU, large subunit LSU, and universal plastid amplicon (UPA) were amplified and sequenced. Maximum likelihood (ML) and Bayesian inference were performed for the phylogenetic analysis. Four single-locus species delimitation methods (SDMs), namely, the generalized mixed Yule-coalescent (GMYC) method, a Poisson tree processes (PTP) model, the automatic barcode gap discovery (ABGD), and the assemble species by automatic partitioning (ASAP) method, were performed to segregate the putative species from other taxa in the Polysiphonia sensu lato clades. Our results revealed that rbcL had 1.4% interspecific genetic divergence, whereas LSU, UPA, and SSU had 1.6%, 2.5%, and 5.4% genetic divergence, respectively, from the nearest neighbors. Both comparative genetic and distinct morphological data revealed that the collected Bay of Bengal specimens comprise a species new to science. In addition, the above-mentioned SDMs supported the genetic data and segregated our specimens as Melanothamnus coxsbazarensis sp. nov. as a distinct species. Full article

Frankenia is a morphologically complex genus, with some species exhibiting a few diagnostic characters and significant morphological variability. This has led to misidentification or the synonymisation of many names based on one or a few diagnostic traits. This phenomenon affects the annual sea-heath, F. pulverulenta, a Eurasian–Mediterranean herb that has become subcosmopolitan, to which several entities have been included due to their shared features, namely their annual lifespan or their flattened leaves. However, this fact also extends to shrubby species, such as the Madeiran F. cespitosa. Here, integrative taxonomic studies, encompassing detailed morphological descriptions of macro- and microcharacters along with molecular phylogenetic analyses of both nuclear ribosomal (ITS1-5.8S-ITS2 region) and plastid (matK gene) DNA sequence data, and an analysis of biogeographic data were undertaken. This examination has resulted in the most complete phylogenetic trees of Frankenia to date, leading to the reinstatement of two African species broadly differing morphologically from F. pulverulenta. Firstly, F. florida L.Chevall., a name applied to a species occurring in the Saharan regions of Algeria, Morocco, Mali, and Mauritania, is often accepted as a variety or subspecies of the annual sea-heath. In contrast, F. densa Pohnert, a species endemic to southern Namibia and northern South Africa, has been synonymised with F. pulverulenta. However, since those two names were later homonyms of two Chilean and Australian plants, they were deemed illegitimate upon publication. Consequently, two new names are proposed for them: F. sahariensis and F. dinteri, respectively. Their substantiation as independent species is provided by data on their morphology, distribution, ecology, and molecular phylogenetics, which demonstrate their distinctiveness from F. pulverulenta. Nomenclatural synonymy and types are also presented for all concerned names, including the designation of two new lectotypes. Furthermore, the importance of an accurate description of the morphological variation in populations is emphasised for a precise identification of taxa in Frankenia. Full article

Camphora Fabr. is a genus in the family Lauraceae, comprising over 20 tropical and subtropical tree species. Since the genera Camphora and Cinnamomum Schaeff. were described, there has been a long-lasting controversy regarding the phylogenetic relationships among taxa in both genera. In particular, phylogenetic inferences derived from plastid data remain debated, with varying hypotheses proposed and occasional disputes concerning the monophyly of Camphora taxa. To further investigate the relationships, We analyzed plastomes and nuclear ribosomal cistron sequences (nrDNA) of 22 Camphora taxa, 15 Cinnamomum taxa, and 13 representative taxa of related genera. The Camphora plastomes range from 152,745 to 154,190 bp, with a GC content of 39.1% to 39.2%. A total of 128 genes were identified in the Camphora plastomes, including 84 protein-coding genes, 8 rRNA genes, and 36 tRNA genes. A total of 1130 SSR loci were detected from plastomes of Camphora, and A/T base repeats looked like the most common. Comparative analyses revealed that the plastomes of Camphora exhibit high similarity in overall structure. The loci ycf1, ycf2, trnK (UUU), psbJ-psbL, and ccsA-ndhD were identified as candidate DNA barcodes for these taxa. Plastome phylogenetic analysis revealed that Camphora is not monophyletic, whereas the nrDNA dataset supported the monophyly of Camphora. We propose that intergeneric hybridization may underlie the observed discordance between plastid and nuclear data in Camphora, and we recommend enhanced taxonomic sampling and precise species identification to improve phylogenetic resolution and accuracy. Full article

Polyploidy is a powerful mechanism driving genetic, physiological, and phenotypic changes among cytotypes of the same species across both large and small geographic scales. These changes can significantly shape population structure and increase the evolutionary and adaptation potential of cytotypes. Alyssum moellendorfianum, an edaphic steno-endemic species with a narrow distribution in the Balkan Peninsula, serves as an intriguing case study. We conducted a comprehensive analysis of genetic diversity and population structure across the species’ range, employing an array of genetic techniques (nuclear microsatellites, amplified fragment length polymorphisms, and plastid DNA sequences), flow cytometry (FCM), morphometry, and pollen analysis. The study reveals two genetic lineages: spatially distributed diploid and tetraploid cytotypes. Clear divergence between diploids and tetraploids was shown by AFLP, while plastid DNA sequences confirmed private haplotypes in each of the studied populations. Higher genetic diversity and allelic richness following the north-south pattern were documented in tetraploids compared to diploids, as indicated by nuclear microsatellites. Morphometric analysis via principal component analysis (PCA) and canonical discriminant analysis (CDA) did not reveal any divergence between diploid and tetraploid cytotypes. Nonetheless, a distinction in pollen size was clearly observed. The results suggest an autopolyploid origin of tetraploids from diploid ancestors. Despite the population fragmentation in a very small geographic range, these populations harbour high genetic diversity, which would allow them to remain stable if natural processes remain undisturbed. Full article

The purpose of this study was to investigate the physiological and biochemical changes of the hepatopancreas and intestinal microbial structure of Penaeus vannamei under various levels of carbonate alkalinity stress. After Penaeus vannamei (body length 14.24 ± 2.13 cm, body weight 26.31 ± 3.26 g) was subjected to 96 h carbonate alkalinity stress, the alkalinity stress levels were E8 (8 mmol/L), E18 (18 mmol/L) and E28 (28 mmol/L), respectively. The activity of antioxidant enzymes was determined by enzyme markers, and then the intestinal microorganisms of Penaeus vannamei were analyzed by high-throughput sequencing technology. The results showed that, under the stress of high carbonate alkalinity, the mortality rate of Penaeus vannamei was as high as 75%, and hepatopancreas cells showed obvious deformation, abnormal nuclear shapes, and serious cell vacuolation. Under high carbonate alkalinity stress, superoxide dismutase activity, catalase activity and glutathione peroxidase activity in the Penaeus vannamei hepatopancreas were significantly lower than those in control group (p < 0.05), and malondialdehyde content was significantly lower than that in the control group (p < 0.05). Alkaline phosphatase activity in the experimental group was significantly different from that in the control group (p < 0.05). Moreover, the 16SrDNA high-throughput sequencing results showed that the intestinal abundance of Proteobacteria in Penaeus vannamei was significantly decreased (p < 0.05) under high carbonate alkalinity stress, and the abundance of Bacteroides was significantly increased (p < 0.05). At the genus level, the abundance of Chrysobacteria was significantly increased (p < 0.05). The functional prediction results of COG and KEGG showed that the functional abundance of RNA polymerase sigma-70 factor is direct bacterial or plastid core RNA polymerase and is specific to promoter elements that are situated 10 and 35 base-pairs upstream of transcription-initiation points—in the high carbonate alkalinity treatment group, this was higher than that in the control group. The functional abundance of signal transduction histidine kinase was lower than that of the control group. The results of this study not only indicated that Penaeus vannamei cell structure would change and mortality would increase under high carbonate alkalinity culture environment, but they also analyzed the changes of the intestinal microbial structure under carbonate alkalinity stress. This study could provide theoretical reference for Penaeus vannamei saline–alkali land culture. Full article

Synsepalum and Englerophytum are two closely related genera of the sub-family Chrysophylloideae in the family Sapotaceae. It has been reported that the two genera are a monophyletic group, and their generic limitations are uncertain. Synsepalum is an economically important genus that includes the medicinally and culinarily important plant, -miracle berry, S. dulcificum. The phylogenetic relationships among the species are poorly understood. This study has been conducted to refine the phylogenetic relationships between and within the two genera utilizing nuclear and chloroplast DNA data. Bayesian analyses and Maximum likelihood of nuclear internal transcribed spacer (ITS) and plastid (trnH-psbA) sequences were used to reconstruct the phylogeny of the two genera. Phylogenetic trees generated for both regions (nuclear and plastid) resulted in the resolution of six clades. Four of the clades correspond to species in the genus Synsepalum and two clades include species of Englerophytum. The two clades of Englerophytum are nested within Synsepalum suggesting that the two genera are closely related and may not merit their current circumscription as distinct genera. Also, Synsepalum is confirmed to constitute more than one lineage suggesting it is not monophyletic in its current definition. Overall, the study suggests the need for a comprehensive evaluation of all species currently recognized in the two genera. Full article

Coastal areas are the most biologically productive and undoubtedly among the most complex ecosystems. Algae are responsible for most of the gross primary production in these coastal regions. However, despite the critical importance of algae for the global ecosystem, the biodiversity of many algal groups is understudied, partially due to the high complexity of morphologically identifying algal species. The current study aimed to take advantage of the recently developed technology for biotic community assessment through the high-throughput sequencing (HTS) of environmental DNA (eDNA), known as the “eDNA metabarcoding”, to characterize littoral algal communities in the Northern Gulf of Mexico (NGoM). This study demonstrated that eDNA metabarcoding, based on the universal plastid amplicon (UPA) and part of the large nuclear ribosomal subunit (LSU) molecular markers, could successfully differentiate coastal biotic communities among littoral zones and geographical locations along the shoreline of the NGoM. The statistical significance of separation between biotic communities was partially dependent on the dissimilarity calculation metric; thus, the differentiation of algal community structure according to littoral zones was more distinct when phylogenetic distances were incorporated into the diversity analysis. Current work demonstrated that the relative abundance of algal species obtained with eDNA metabarcoding matches previously established zonation patterns for these species. In addition, the present study detected molecular signals of 44 algal species without previous reports for the Gulf of Mexico, thus providing an important, molecular-validated baseline of species richness for this region. Full article

The genus Hedysarum L. (Fabaceae) includes about 200 species of annual and perennial herbs distributed in Asia, Europe, North Africa, and North America. Many species of this genus are valuable medicinal, melliferous, and forage resources. In this review, we consider the taxonomic history of the genus Hedysarum, the chromosomal organization of the species from the sections Hedysarum and Multicaulia, as well as phylogenetic relationships between these sections. According to morphological, genetic, and phylogenetic data, the genus Hedysarum is divided into three main sections: Hedysarum (= syn. Gamotion), Multicaulia, and Stracheya. In species of this genus, two basic chromosome numbers, x = 7 (section Hedysarum) and x = 8 (sections Multicaulia and Stracheya), were determined. The systematic positions of some species within the sections are still uncertain due to their morphological similarities. The patterns of distribution of molecular chromosomal markers (45S rDNA, 5S rDNA, and different satellite DNAs) in karyotypes of various Hedysarum species made it possible to determine their ploidy status and also specify genomic relationships within the sections Hedysarum and Multicaulia. Recent molecular phylogenetic studies clarified significantly the taxonomy and evolutionary development of the genus Hedysarum. Full article

Numerous Cymbidium species have significant commercial value globally due to their exotic ornamental flowers. Identifying Cymbidium species is challenging due to their similar shapes, which hinders their rational use and the conservation of germplasm resources. In the present study, firstly, four plastid loci (matK, rbcL, psbA-trnH, and atpF-atpH) and a nuclear locus (internal transcribed spacer, ITS) were initially examined to identify Cymbidium species. Secondly, we inferred the interspecific phylogeny of Cymbidium species using ITS sequences. All of these DNA regions, with the exception of atpF-atpH, could be readily amplified from Cymbidium, and the corresponding DNA sequences can be successfully obtained by sequencing. Our research demonstrated that ITS exhibited the highest intra- and interspecific divergences, the greatest barcoding gap, and the highest proportion of species identification. The phylogenetic analysis of Cymbidium species based on the ITS regions primarily corroborated the results obtained using traditional morphological methods. A comparative analysis of candidate DNA barcodes has shown that the ITS can be used not only for barcoding Cymbidium species but also for the phylogenetic analysis of Cymbidium. Full article

Rare and vulnerable endemic plants represent different evolutionary units that occur at different times, and protecting these species is a key issue in biological protection. Understanding the impact of the history of endangered plant populations on their genetic diversity helps to reveal evolutionary history and is crucial for guiding conservation efforts. Saussurea involucrata, a perennial alpine species mainly distributed in the Tianshan Mountains, is famous for its medicinal value but has become endangered due to over-exploitation. In the present study, we employed both nuclear and chloroplast DNA sequences to investigate the genetic distribution pattern and evolutionary history of S. involucrata. A total of 270 individuals covering nine S. involucrata populations were sampled for the amplification and sequencing of nrDNA Internal Transcribed Spacer (ITS) and chloroplast trnL-trnF, matK and ndhF-rpl32 sequences. Via calculation, we identified 7 nuclear and 12 plastid haplotypes. Among the nine populations, GL and BA were characterized by high haplotype diversity, whereas BG revealed the lowest haplotype diversity. Molecular dating estimations suggest that divergence among S. involucrata populations occurred around 0.75 Ma, coinciding with the uplift of Tianshan Mountains. Our results reveal that both isolation-by-distance (IBD) and isolation-by-resistance (IBR) have promoted genetic differentiation among populations of S. involucrata. The results from the ecological niche modeling analyses show a more suitable habitat for S. involucrata in the past than at present, indicating a historical distribution contraction of the species. This study provides new insight into understanding the genetic differentiation of S. involucrata, as well as the theoretical basis for conserving this species. Full article

Our previous study has demonstrated that the nuclear-origin supplementation of the PSII core subunit D1 protein stimulates growth and increases grain yields in transgenic rice plants by enhancing photosynthetic efficiency. In this study, the underlying mechanisms have been explored regarding how the enhanced photosynthetic capacity affects metabolic activities in the transgenic plants of rice harboring the integrated transgene RbcS^PTP-OspsbA cDNA, cloned from rice, under control of the AtHsfA2 promoter and N-terminal fused with the plastid-transit peptide sequence (PTP) cloned from the AtRbcS. Here, a comparative metabolomic analysis was performed using LC-MS in flag leaves of the transgenic rice plants during the grain-filling stage. Critically, the dramatic reduction in the quantities of nucleotides and certain free amino acids was detected, suggesting that the increased photosynthetic assimilation and grain yield in the transgenic plants correlates with the reduced contents of free nucleotides and the amino acids such as glutamine and glutamic acid, which are cellular nitrogen sources. These results suggest that enhanced photosynthesis needs consuming more free nucleotides and nitrogen sources to support the increase in biomass and yields, as exhibited in transgenic rice plants. Unexpectedly, dramatic changes were measured in the contents of flavonoids in the flag leaves, suggesting that a tight and coordinated relationship exists between increasing photosynthetic assimilation and flavonoid biosynthesis. Consistent with the enhanced photosynthetic efficiency, the substantial increase was measured in the content of starch, which is the primary product of the Calvin–Benson cycle, in the transgenic rice plants under field growth conditions. Full article