Explore the vast range of titles available.

Lycophytes are a key group for understanding vascular plant evolution. Lycophyte plastomes are highly distinct, indicating a dynamic evolutionary history, but detailed evaluation is hindered by the limited availability of sequences. Eight diverse plastomes were sequenced to assess variation in structure and functional content across lycophytes. Lycopodiaceae plastomes have remained largely unchanged compared with the common ancestor of land plants, whereas plastome evolution in Isoetes and especially Selaginella is highly dynamic. Selaginella plastomes have the highest GC content and fewest genes and introns of any photosynthetic land plant. Uniquely, the canonical inverted repeat was converted into a direct repeat (DR) via large-scale inversion in some Selaginella species. Ancestral reconstruction identified additional putative transitions between an inverted and DR orientation in Selaginella and Isoetes plastomes. A DR orientation does not disrupt the activity of copy-dependent repair to suppress substitution rates within repeats. Lycophyte plastomes include the most archaic examples among vascular plants and the most reconfigured among land plants. These evolutionary trends correlate with the mitochondrial genome, suggesting shared underlying mechanisms. Copy-dependent repair for DR localized genes indicates that recombination and gene conversion are not inhibited by the DR orientation. Gene relocation in lycophyte plastomes occurs via overlapping inversions rather than transposase/recombinase-mediated processes.

The fossil record provides an invaluable insight into the temporal origins of extant lineages of organisms. However, establishing the relationships between fossils and extant lineages can be difficult in groups with low rates of morphological change over time. Molecular dating can potentially circumvent this issue by allowing distant fossils to act as calibration points, but rate variation across large evolutionary scales can bias such analyses. In this study, we apply multiple dating methods to genome-wide datasets to infer the origin of extant species of Isoetes, a group of mostly aquatic and semi-aquatic isoetalean lycopsids, which closely resemble fossil forms dating back to the Triassic. Rate variation observed in chloroplast genomes hampers accurate dating, but genome-wide nuclear markers place the origin of extant diversity within this group in the mid-Paleogene, 45-60 million years ago. Our genomic analyses coupled with a careful evaluation of the fossil record indicate that despite resembling forms from the Triassic, extant Isoetes species do not represent the remnants of an ancient and widespread group, but instead have spread around the globe in the relatively recent past.

Background: Breast cancer, the most prevalent cancer among women globally, develops primarily in the breast’s ducts or lobules. Drug resistance is a significant challenge in treating advanced cases, contributing to over 685,000 breast cancer-related deaths annually, and identifying novel compounds that inhibit key proteins is crucial for developing effective therapies. Methods: In this study, five transferase proteins with PDB IDs were selected due to their involvement in breast cancer: 1A52, 3PP0, 4EJN, 4I23, and 7R9V. Multitargeted docking studies were conducted using three different docking strategies and Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) to calculate the binding affinities against the ZINC Natural compound library. Isoetin (ZINC000006523948), found mainly in Isoetaceae, was identified, and the results were compared with the Food and Drug Administration (FDA)-approved drug Tucatinib. In addition, molecular interaction fingerprints and pharmacokinetic profiling were evaluated. We also performed 5 ns WaterMap simulations to identify hydration sites and interactions, followed by 100 ns molecular dynamics (MD) simulations and MM/GBSA to assess the stability of the Isoetin–protein complexes. Results: The docking results indicated that Isoetin demonstrated superior binding and docking scores ranging from −9.901 to −13.903 kcal/mol compared to Tucatinib, which showed values between −4.875 and −10.948 kcal/mol, suggesting Isoetin’s potential efficacy as a therapeutic agent for breast cancer. Interaction fingerprints revealed significant interactions between Isoetin and key residues, including 28LEU, 12MET, 9PHE, 7ASP, 6ASN, and 6THR. The pharmacokinetics and DFT analysis of Isoetin supported its potential as a viable drug candidate. Furthermore, the 5 ns WaterMap simulations identified various hydration sites, and the 100 ns MD simulations showed that the Isoetin–protein complexes exhibited minimal deviations and fluctuations, indicating better stability than Tucatinib, and MM/GBSA confirmed Isoetin’s superior binding stability. Conclusions: Isoetin, a natural compound identified through in silico screening, demonstrates significant promise as a potential therapeutic agent for breast cancer as it outperforms the FDA-approved drug Tucatinib, the respective native and FDA-approved drug. However, experimental validation is necessary before considering Isoetin for clinical use.

Isoetes are ancient quillworts members of the only genus of the order Isoetales. The genus is slow evolving but is resilient, and widespread worldwide. Two recently described species occur in the Eastern Brazilian Amazon, Isoetes serracarajensis and Isoetes cangae. They are found in the ironstone grasslands known as Canga. While I. serracarajensis is present mostly in seasonal water bodies, I. cangae is known to occur in a single permanent lake at the South mountain range. In this work, we undertake an extensive morphological, physiological and genetic characterization of both species to establish species boundaries and better understand the morphological and genetic features of these two species. Our results indicate that the morphological differentiation of the species is subtle and requires a quantitative assessment of morphological elements of the megaspore for diagnosis. We did not detect differences in microspore output, but morphological peculiarities may establish a reproductive barrier. Additionally, genetic analysis using DNA barcodes and whole chloroplast genomes indicate that although the plants are genetically very similar both approaches provide diagnostic characters. There was no indication of population structuring I. serracarajensis. These results set the basis for a deeper understanding of the evolution of the Isoetes genus.

Background Merlin’s grass ( Isoetes , Isoetaceae, Lycopsida), is the extant remnant of the isoetalean wood-producing lycopsids that originated during the Paleozoic, possibly in aquatic or boggy habitats. Modern day species are aquatic, semi-aquatic or terrestrial and occur almost worldwide. They display little morphological variation; the lobed corm has helically arranged leaves with internal air channels and basal sporangia. Genetic variation has also proven limited, which has hampered phylogenetic inference. We investigate evolutionary relationships in Isoetes , using molecular data and an extended sample of species compared to previous work, adding species that have never before been included in a phylogenetic study. Results Our results reveal an unexpected discovery of an “ Amborella syndrome” in Isoetaceae: a single poorly known species is sister to the remaining family. The species, Isoetes wormaldii , is a rare endemic to the Eastern Cape of South Africa. Its leaves are flattened with a rounded point, which sharply contrasts with the awl-shaped leaves of most other species of Isoetes . The remaining species of Isoetes are resolved in five major clades, also indicated in previous work. While the phylogeny shows geographic structure, the patterns are complex. For example, tropical-southern African species occur in at least five clades, and Indian, Australian and Mediterranean species in at least three clades each. Conclusion The evolutionary and biogeographical history of Isoetes is not easily explained, and may conceivably include ample extinction and a mixture of ancient and more recent processes. Previously shown difficulties with node age estimation increase the problem. The here demonstrated sister-relationship between the phylogenetically, morphologically and genetically distinct Isoetes wormaldii and the remaining family appears to bridge the morphological gap between Isoetes and its extinct relatives, although further studies are needed. Moreover, it shortens the branch length to its living sister genus Selaginella , and may enhance node age estimation in future studies. Isoetes wormaldii is critically endangered, known only from one (to a few) minor populations. Immediate actions need to be taken if we want to prevent this unique species from going extinct.

Background Despite considerable progress in our understanding of land plant phylogeny, several nodes in the green tree of life remain poorly resolved. Furthermore, the bulk of currently available data come from only a subset of major land plant clades. Here we examine early land plant evolution using complete plastome sequences including two previously unexamined and phylogenetically critical lineages. To better understand the evolution of land plants and their plastomes, we examined aligned nucleotide sequences, indels, gene and nucleotide composition, inversions, and gene order at the boundaries of the inverted repeats. Results We present the plastome sequences of Equisetum arvense , a horsetail, and of Isoetes flaccida , a heterosporous lycophyte. Phylogenetic analysis of aligned nucleotides from 49 plastome genes from 43 taxa supported monophyly for the following clades: embryophytes (land plants), lycophytes, monilophytes (leptosporangiate ferns + Angiopteris evecta + Psilotum nudum + Equisetum arvense ), and seed plants. Resolution among the four monilophyte lineages remained moderate, although nucleotide analyses suggested that P. nudum and E. arvense form a clade sister to A. evecta + leptosporangiate ferns. Results from phylogenetic analyses of nucleotides were consistent with the distribution of plastome gene rearrangements and with analysis of sequence gaps resulting from insertions and deletions (indels). We found one new indel and an inversion of a block of genes that unites the monilophytes. Conclusions Monophyly of monilophytes has been disputed on the basis of morphological and fossil evidence. In the context of a broad sampling of land plant data we find several new pieces of evidence for monilophyte monophyly. Results from this study demonstrate resolution among the four monilophytes lineages, albeit with moderate support; we posit a clade consisting of Equisetaceae and Psilotaceae that is sister to the \"true ferns,\" including Marattiaceae.

A new endemic species of Isoetes from Fujian, China, which was previously identified as I. orientalis, is described and illustrated. In this study, we observed its leaf cross‐cut characteristics under a microscope and spore morphology characteristics under a scanning electron microscope, counted its chromosome number, and compared population genetic differences between this hexaploid and I. orientalis based on single nucleotide polymorphisms (SNPs) extracted from whole‐genome resequencing data. We found that this hexaploid differs from I. orientalis in both leaf morphology and spore ornamentation, and that the two also exhibit significant differences in population genetics. Based on this comprehensive evidence, we identified the hexaploid as a new species and named it I. fokiensis. Here, we formally describe this hexaploid species and provide an identification key to the Isoetes species reported from China. A new endemic species of Isoetes from Fujian, China, which was previously identified as I. orientalis, is described and illustrated. In this study, we observed its leaf across‐cut characteristics under the microscope and spore morphology characteristics under the scanning electron microscope, counted its chromosome number, and compared population genetic differences between this hexaploid and I. orientalis based on single nucleotide polymorphisms (SNPs) extracted from whole‐genome resequencing data. We found that this hexaploid differs from I. orientalis in both leaf morphology and spore ornamentation, and that the two also exhibit significant differences in population genetics. Based on this comprehensive evidence, we identified the hexaploid as a new species and named it I. fokiensis. Here, we formally describe this hexaploid species and provide an identification key to the Isoetes species reported from China.

Submersed aquatic plants are a key component of shallow, clear water lakes contributing to primary production and water quality. High mountain lakes are naturally fishless although invasive trout and most recently minnows have been introduced causing a major impact on fauna richness. The Pyrenean high mountain range has preserved soft-water oligotrophic boreal isoetids in their southern limit of distribution but the recent fish introduction is a potential factor of stress that needs to be addressed. We here work under the hypothesis that due to contrasting ecological features, trout will not be heavily affecting quillwort populations while minnows will have a stronger effect on zooplankton and zoobenthos that will promote algal growth and reduce light availability for the underwater meadows. Ten Pyrenean shallow lakes representative of three scenarios -fishless, with trout and with minnows-, were sampled for meadow structure, water column and benthic environment characterization in mid-summer 2015 and 2016. Quillwort biomass allocation (above vs. belowground), epiphytic load, and composition of the algal community (abundant cyanobacteria) differed in the presence of minnows. In trout lakes biomass allocation and epiphytic load were average and the algal community composed by chlorophytes and diatoms as in fishless lakes. Biomass ratio was close to thresholds of negative buoyancy in minnow lakes indicating that meadows were at risk of uprooting and consequent de-vegetation. Total and soluble carbohydrates were lower and the sporangia contained significantly less reserves to constrain growth and expansion in the presence of minnows. Lake scenarios were coupled to physicochemical differences with low light, high phosphorus and Chl-a (mesotrophia) in minnow lakes, while trout and fishless lakes remained oligotrophic. This is the first study assessing the impact of non-native fish on soft-water isoetids from mountain lakes and shows that minnows are a major threat to quillworts. The impaired light environment (from epiphytic algal overgrow and water column Chl-a) entails consequent regression (i.e., no recruitment) and de-vegetation (uprooting) of the meadows. Since soft-water oligotrophic mountain lakes are protected under the Habitats Directive, some action needs to be urgently implemented not only to preserve quillworts but to the overall ecological integrity of the lakes.

S.W. Leonard, W.C. Taylor, L.J. Musselman and R.D. Bray (Isoetaceae, Lycopodiophyta) is a new species known from two sites along tributaries of the Pearl River in southern Mississippi. This species is distinguished from other species in the southeastern United States by a combination of character states including a basic diploid (2n=22) chromosome count, laevigate megaspores, and a narrow velum covering less than one-third of the adaxial sporangium wall.