Search Results (7)

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

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

Rhodomyrtus tomentosa is a source of a novel antibiotic, rhodomyrtone. Because of the increasing industrial demand for this compound, germplasm with a high rhodomyrtone content is the key to sustainable future cultivation. In this study, rhodomyrtone genotypes were verified using the plastid genomic region marker matK and nuclear ribosomal internal transcribed spacer ITS. These two DNA barcodes proved to be useful tools for identifying different rhodomyrtone contents via the SNP haplotypes C569T and A561G, respectively. The results were correlated with rhodomyrtone content determined via HPLC. Subsequently, R. tomentosa samples with high- and low-rhodomyrtone genotypes were collected for de novo transcriptome and gene expression analyses. A total of 83,402 unigenes were classified into 25 KOG classifications, and 74,102 annotated unigenes were obtained. Analysis of differential gene expression between samples or groups using DESeq2 revealed highly expressed levels related to rhodomyrtone content in two genotypes. semiquantitative RT-PCR further revealed that the high rhodomyrtone content in these two genotypes correlated with expression of zinc transporter protein (RtZnT). In addition, we found that expression of RtZnT resulted in increased sensitivity of R. tomentosa under ZnSO₄ stress. The findings provide useful information for selection of cultivation sites to achieve high rhodomyrtone yields in R. tomentosa. Full article

At the end of the 1920s, Vavilov organized several potato-collecting missions in South and Central America. Vavilov and his colleagues, Juzepczuk and Bukasov, participated in these expeditions and worked on gathered material, designated two centers of potato varietal riches and diversity—the Peru–Bolivia high-mountain center and the southern coast of Chile. The WIR Herbarium holds authentic specimens of many taxa described by Russian taxonomists. Here, a set of 20 plastid DNA-specific markers was applied for 49 authentic herbarium specimens of Solanum tuberosum L. from the WIR Herbarium to analyze the genetic diversity of the landrace population collected by Juzepczuk in 1928 in southern–central Chile. Two plastid DNA types, T and A, and two chlorotypes were identified in herbarium specimens, with a clear predominance (96%) of chlorotype cpT_III. In addition, we analyzed 46 living Chilean accessions from the VIR field potato gene bank that were collected after the appearance of Phytophthora infestans in Chile. These living accessions were differentiated into four chlorotypes. Finding a D-type cytoplasm in living Chilean accessions that possess two new chlorotypes indicates a replacement of native cultivars and introgression from the wild Mexican species S. demissum that was actively used in breeding as a source of race-specific resistance to late blight. Full article

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

A collection of cultivated Liriope and Ophiopogon plants was established in 1996–1998 and subsequently hosted at a horticultural college. Uncertainties about the identification of the accessions, compounded by potential errors in propagation and labelling have led to waning confidence in the identities of the plants in the collection. The potential for using DNA barcoding to determine the species identities of the accessions was investigated. The DNA barcode regions of the plastid ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit gene (rbcL) and nuclear ribosomal internal transcribed spacer (nrITS) were amplified. DNA sequence analysis allowed the sequences of the accessions to be compared to reference sequences in public databases. A simple haplotype map of the characteristic polymorphic positions in the rbcL regions was used to clearly distinguish between the two genera and assign Ophiopogon accessions to individual species or sub-groups of species. The ITS sequence data confirmed these genus and species assignations and provided greater resolution to distinguish between closely related species. The combination of two DNA barcodes allowed most of the accessions to be assigned to individual species. This molecular verification confirmed the identity of about 70% of the accessions, with the remaining 30% demonstrating a range of mistaken identities at the species and genus levels. Full article

Taxus is a genus of trees and shrubs with high value in horticulture and medicine as a source of the anticancer drug paclitaxel. The taxonomy of the group is complex due to the lack of diagnostic morphological characters and the high degree of similarity among species. Taxus has a wide global geographic distribution and some taxonomists recognize only a single species with geographically defined subgroups, whereas others have described several species. To address these differences in taxonomic circumscription, phylogenetic analyses were conducted on DNA sequences using Maximum Likelihood, Bayesian Inference and TCS haplotype networks on single and combined gene regions obtained for the nuclear ribosomal ITS region and the plastid trnL intron and trnL-F intergenic spacer. Evidence is presented for the sister group status of Pseudotaxus to Taxus and the inclusion of Amentotaxus, Austrotaxus, Cephalotaxus and Torreya within Taxaceae. Results are consistent with the taxonomic recognition of nine species: T. baccata, T. brevifolia, T. canadensis, T. cuspidata, T. floridana, T. fuana, T. globosa, T. sumatrana and T. wallichiana, but evidence is found for less species distinction and considerable reticulation within the T. baccata, T. canadensis and T. cuspidata group. We compare the results to known taxonomy, biogeography, present new leaf anatomical data and discuss the origins of the hybrids T. ×media and T. ×hunnewelliana. Full article