Search

The genus Selaginella holds a key phylogenetic position as a sister species to vascular plants, encompassing desiccation-tolerant members. Some Selaginella species thrive in extremely arid conditions, enduring significant water loss and recovering upon rehydration. Consequently, Selaginella has emerged as a model system for studying desiccation tolerance in plant science. However, the absence of an efficient genetic transformation system has limited the utility of Selaginella species as a model. To address this constraint, we developed a nanoparticle-mediated transformation tool utilizing arginine-functionalized nanohydroxyapatites. This biocompatible system enabled the transient expression of the GFP , GUS , and eYGFPuv reporter genes in Selaginella moellendorffii . Establishing a stable genetic transformation technique for S. moellendorffii holds promise for application to other Selaginella species. This tool could be instrumental in identifying genetic resources for crop improvement and understanding genome-level regulatory mechanisms governing desiccation tolerance in Selaginella species. Furthermore, this tool might aid in identifying key regulatory genes associated with desiccation tolerance, offering potential applications in enhancing drought-sensitive crops and ensuring sustainable food production.

Within the ancient vascular plant lineage known as lycophytes, many Selaginella species contain only one giant chloroplast in the upper epidermal cells of the leaf. In deep-shade species, such as S. martensii, the chloroplast is cup-shaped and the thylakoid system differentiates into an upper lamellar region and a lower granal region (bizonoplast). In this report, we describe the ultrastructural changes occurring in the giant chloroplast hosted in the epidermal cells of S. martensii during the daily relocation of the organelle. The process occurs in up to ca. 40% of the microphylls without the plants being exposed to high-light flecks. The relocated chloroplast loses its cup shape: first, it flattens laterally toward the radial cell wall and then assumes a more globular shape. The loss of the conical cell shape, the side-by-side lateral positioning of vacuole and chloroplast, and the extensive rearrangement of the thylakoid system to only granal cooperate in limiting light absorption. While the cup-shaped chloroplast emphasizes the light-harvesting capacity in the morning, the relocated chloroplast is suggested to support the renewal of the thylakoid system during the afternoon, including the recovery of photosystem II (PSII) from photoinhibition. The giant chloroplast repositioning is part of a complex reversible reshaping of the whole epidermal cell., (© 2023. The Author(s).)

Plant roots originated independently in lycophytes and euphyllophytes, whereas early vascular plants were rootless. The organization of the root apical meristem in euphyllophytes is well documented, especially in the model plant Arabidopsis. However, little is known about lycophyte roots and their molecular innovations during evolution. In this study, spatial transcriptomics was used to detect 97 root-related genes in the roots of the lycophyte Selaginella moellendorffii. A high number of genes showed expression patterns similar to what has been reported for seed plants, supporting the idea of a highly convergent evolution of mechanisms to control root development. Interaction and complementation data of SHORTROOT (SHR) and SCARECROW (SCR) homologs, furthermore, support a comparable regulation of the ground tissue (GT) between euphyllophytes and lycophytes. Root cap formation, in contrast, appears to be differently regulated. Several experiments indicated an important role of the WUSCHEL-RELATED HOMEOBOX13 gene SmWOX13a in Selaginella root cap formation. In contrast to multiple Arabidopsis WOX paralogs, SmWOX13a is able to induce root cap cells in Arabidopsis and has functionally conserved homologs in the fern Ceratopteris richardii. Lycophytes and a part of the euphyllophytes, therefore, may share a common mechanism regulating root cap formation, which was diversified or lost during seed plant evolution. In summary, we here provide a new spatial data resource for the Selaginella root, which in general advocates for conserved mechanisms to regulate root development but shows a clear divergence in the control of root cap formation, with a novel putative role of WOX genes in root cap formation in non-seed plants., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Metallic nanoparticles from different natural sources exhibit superior therapeutic options as compared to the conventional methods. Selaginella species have attracted special attention of researchers worldwide due to the presence of bioactive molecules such as flavonoids, biflavonoids, triterpenes, steroids, saponins, tannins and other secondary metabolites that exhibit antimicrobial, antiplasmodial, anticancer and anti-inflammatory activities. Environment friendly green synthesised silver nanoparticles from Selaginella species provide viable, safe and efficient treatment against different fungal pathogens., Objective: This systematic review aims to summarise the literature pertaining to superior antifungal ability of green synthesised silver nanoparticles using plant extracts of Selaginella spp. in comparison to both aqueous and ethanolic raw plant extracts by electronically collecting articles from databases., Methods: The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis were taken into consideration while preparing this review. The titles and abstracts of the collected data were stored in Endnote20 based on the inclusion and exclusion criteria. The search strategy included literature from established sources like PubMed, Google Scholar and Retrieval System Online using subject descriptors., Results: The search yielded 60 articles with unique hits. After removal of duplications, 46 articles were identified, 40 were assessed and only seven articles were chosen and included in this review based on our eligibility criteria., Conclusion: The physicochemical and preliminary phytochemical investigations of Selaginella suggest higher drug potency of nanoparticles synthesised from plant extract against different diseases as compared to aqueous and ethanolic plant extracts. The study holds great promise as the synthesis of nanoparticles involves low energy consumption, minimal technology and least toxic effects.

Six compounds including three new benzophenones, selagibenzophenones D-F ( 1 - 3 ), two known selaginellins ( 4 - 5 ) and one known flavonoid ( 6 ), were isolated from Selaginella tamariscina . The structures of new compounds were established by 1D-, 2D-NMR and HR-ESI-MS spectral analyses. Compound 1 represents the second example of diarylbenzophenone from natural sources. Compound 2 possesses an unusual biphenyl-bisbenzophenone structure. Their cytotoxicity against human hepatocellular carcinoma HepG2 and SMCC-7721 cells and inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells were evaluated. Compound 2 showed moderate inhibitory activity against HepG2 and SMCC-7721 cells, and compounds 4 and 5 showed moderate inhibitory activity to HepG2 cells. Compounds 2 and 5 also exhibited inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production.

Despite the many strategies employed to slow the spread of cancer, the development of new anti-tumor drugs and the minimization of side effects have been major research hotspots in the anti-tumor field. Natural drugs are a huge treasure trove of drug development, and they have been widely used in the clinic as anti-tumor drugs. Selaginella species in the family Selaginellaceae are widely distributed worldwide, and they have been well-documented in clinical practice for the prevention and treatment of cancer. Biflavonoids are the main active ingredients in Selaginella , and they have good biological and anti-tumor activities, which warrant extensive research. The promise of biflavonoids from Selaginella (SFB) in the field of cancer therapy is being realized thanks to new research that offers insights into the multi-targeting therapeutic mechanisms and key signaling pathways. The pharmacological effects of SFB against various cancers in vitro and in vivo are reviewed in this review. In addition, the types and characteristics of biflavonoid structures are described in detail; we also provide a brief summary of the efforts to develop drug delivery systems or combinations to enhance the bioavailability of SFB monomers. In conclusion, SFB species have great potential to be developed as adjuvant or even primary therapeutic agents for cancer, with promising applications.

Diverse branching forms have evolved multiple times across the tree of life to facilitate resource acquisition and exchange with the environment. In the vascular plant group, the ancestral pattern of branching involves dichotomy of a parent shoot apex to form two new daughter apices. The molecular basis of axillary branching in Arabidopsis is well understood, but few regulators of dichotomous branching are known. Through analyses of dichotomous branching in the lycophyte, Selaginella kraussiana, we identify PIN-mediated auxin transport as an ancestral branch regulator of vascular plants. We show that short-range auxin transport out of the apices promotes dichotomy and that branch dominance is globally coordinated by long-range auxin transport. Uniquely in Selaginella, angle meristems initiate at each dichotomy, and these can develop into rhizophores or branching angle shoots. We show that long-range auxin transport and a transitory drop in PIN expression are involved in angle shoot development. We conclude that PIN-mediated auxin transport is an ancestral mechanism for vascular plant branching that was independently recruited into Selaginella angle shoot development and seed plant axillary branching during evolution., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Filmy ferns (Hymenophyllaceae) are the most diverse lineage of the early-diverging leptosporangiate ferns with ca. 430 species widely distributed around the world but with the highest diversity in the humid tropics. However, their fossil record is scarce because of the low preservation potential of the delicate, membranous laminae. So far, no Hymenophyllaceae fossils have been reported from tropical Asia. Here, we describe some fern remains and their syninclusions (spike-mosses) in four pieces of Kachin amber from the mid-Cretaceous of Hukawng Valley, Northern Myanmar, as Hymenophyllites angustus sp. nov., H . kachinensis sp. nov., H . setosus sp. nov. (Hymenophyllaceae) and Selaginella alata sp. nov. (Selaginellaceae), respectively. These fern remains are assigned to Hymenophyllaceae based on the filmy, one-cell thick, decompound pinnatifid laminae and dichotomous venation. They represent the first fossil record of Hymenophyllaceae in tropical Asia. The growth habits of these ferns and associated spike-mosses and their implication for paleoenvironment are discussed. Our study expands the diversity of the cryptogams in mid-Cretaceous Kachin amber. Together with other contemporaneous findings, the present fossils indicate that Hymenophyllaceae have already accumulated some notable diversity in the Cretaceous.

Seedling vigor is a key agronomic trait that determines juvenile plant performance. Angiosperm seeds develop inside fruits and are connected to the mother plant through vascular tissues. Their formation requires plant-specific genes, such as BREVIS RADIX (BRX) in Arabidopsis thaliana roots. BRX family proteins are found throughout the euphyllophytes but also occur in non-vascular bryophytes and non-seed lycophytes. They consist of four conserved domains, including the tandem BRX domains. We found that bryophyte or lycophyte BRX homologs can only partially substitute for Arabidopsis BRX (AtBRX) because they miss key features in the linker between the BRX domains. Intriguingly, however, expression of a BRX homolog from the lycophyte Selaginella moellendorffii (SmBRX) in an A. thaliana wild-type background confers robustly enhanced root growth vigor that persists throughout the life cycle. This effect can be traced to a substantial increase in seed and embryo size, is associated with enhanced vascular tissue proliferation, and can be reproduced with a modified, SmBRX-like variant of AtBRX. Our results thus suggest that BRX variants can boost seedling vigor and shed light on the activity of ancient, non-angiosperm BRX family proteins., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2022. Published by The Company of Biologists Ltd.)

While most plants die below a threshold of water content, desiccation-tolerant species display specific responses that allow them to survive extreme dehydration. Some of these responses are activated at critical stages during water loss and could represent the difference between desiccation tolerance (DT) and death. Here, we report the development of a simple and reproducible system to determine DT in Selaginella species. The system is based on exposure of excised tissue to a dehydration agent inside small containers, and subsequent evaluation for tissue viability. We evaluated several methodologies to determine viability upon desiccation including: triphenyltetrazolium chloride (TTC) staining, the quantum efficiency of PSII, antioxidant potential, and relative electrolyte leakage. Our results show that the TTC test is a simple and accurate assay to identify novel desiccation-tolerant Selaginella species, and can also indicate viability in other desiccation-tolerant models (i.e. ferns and mosses). The system we developed is particularly useful to identify critical points during the dehydration process. We found that a desiccation-sensitive Selaginella species shows a change in viability when dehydrated to 40% relative water content, indicating the onset of a critical condition at this water content. Comparative studies at critical stages could provide a better understanding of DT mechanisms and unravel insights into the key responses to survive desiccation., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

In the context of plant evolution, pteridophytes, which is comprised of lycophytes and ferns, occupy an intermediate position between bryophytes and seed plants, sharing characteristics with both groups. Pteridophytes is a highly diverse group of plant species that occupy a wide range of habitats including ecosystems with extreme climatic conditions. There is a significant number of pteridophytes that can tolerate desiccation by temporarily arresting their metabolism in the dry state and reactivating it upon rehydration. Desiccation-tolerant pteridophytes exhibit a strategy that appears to be intermediate between the constitutive and inducible desiccation tolerance (DT) mechanisms observed in bryophytes and angiosperms, respectively. In this review, we first describe the incidence and anatomical diversity of desiccation-tolerant pteridophytes and discuss recent advances on the origin of DT in vascular plants. Then, we summarize the highly diverse adaptations and mechanisms exhibited by this group and describe how some of these plants could exhibit tolerance to multiple types of abiotic stress. Research on the evolution and regulation of DT in different lineages is crucial to understand how plants have adapted to extreme environments. Thus, in the current scenario of climate change, the knowledge of the whole landscape of DT strategies is of vital importance as a potential basis to improve plant abiotic stress tolerance.

A new biflavonoid, (2''S)-6''-methyl-2'',3''-dihydroochnaflavone (1), along with two known ochnaflavones (2, 3), four known amentoflavones (4-7) and two known robustaflavones (8, 9) were obtained from the 70% EtOH extract of Selaginella trichoclada. The chemical structures of isolated compounds were elucidated by extensive spectroscopic analyses. Overall, compounds 1-9 displayed moderate cytotoxic effects against human breast cancer MCF-7 cell lines. Among them, compounds 2 and 8 exhibited relatively strong cytotoxic effects against MCF-7 cells with an IC 50 value of 7.7 and 6.9 μΜ, respectively. The results of RNA-sequencing and KEGG functional enrichment analysis showed that 8 could induce ferroptosis in MCF-7 cells by down-regulating the expression of ferroptosis-related genes including ACSL4, NOXO1, NOXA1, ACSL5, STEAP3, LPCAT3, ATG7 and TP53. Then 8 could inhibit the expression of ACSL4 proteins through molecule docking analysis, which showed a strong interaction of - 11.89 Kcal/mol binding energy. Those results indicate that 8 could be chemotherapy agents to fight drug resistance in breast cancer by down-regulating the expression level of ACSL4 proteins via ferroptosis, which needs to be further certified in vitro., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

All Evo-Devo studies rely on representative sampling across the tree of interest to elucidate evolutionary trajectories through time. In land plants, genetic resources are well established in model species representing lineages including bryophytes (mosses, liverworts, and hornworts), monilophytes (ferns and allies), and seed plants (gymnosperms and flowering plants), but few resources are available for lycophytes (club mosses, spike mosses, and quillworts). Living lycophytes are a sister group to the euphyllophytes (the fern and seed plant clade), and have retained several ancestral morphological traits despite divergence from a common ancestor of vascular plants around 420 million years ago. This sister relationship offers a unique opportunity to study the conservation of traits such as sporophyte branching, vasculature, and indeterminacy, as well as the convergent evolution of traits such as leaves and roots which have evolved independently in each vascular plant lineage. To elucidate the evolution of vascular development and leaf formation, molecular studies using RNA Seq, quantitative reverse transcription polymerase chain reaction, in situ hybridisation and phylogenetics have revealed the diversification and expression patterns of KNOX, ARP, HD-ZIP, KANADI, and WOX gene families in lycophytes. However, the molecular basis of further trait evolution is not known. Here we describe morphological traits of living lycophytes and their extinct relatives, consider the molecular underpinnings of trait evolution and discuss future research required in lycophytes to understand the key evolutionary innovations enabling the growth and development of all vascular plants., (© 2020 The Authors. Evolution & Development published by Wiley Periodicals LLC.)

Breast cancer is one of the major malignant tumors in females, and currently, recurrence and metastasis are the main obstacles preventing effective breast cancer treatment. Biflavonoids of secondary metabolites from plants are excellent anticancer agents to fight sensitive and resistant breast cancer cell lines. In this study, six C-3'-C-6″ biflavonoids, including one new robustaflavone A (1, RF-A) and five known robustaflavone derivatives (2-6), were isolated from Selaginella trichoclada for the first time. We aimed to evaluate the inhibitory effects of compounds 1-6 against human breast cancer MCF-7 cells. Among the six compounds, RF-A showed the strongest activity, decreasing cell viability with an IC 50 value of 11.89 μΜ. Furthermore, RF-A strikingly induced MCF-7 nonapoptotic cell death through ferroptosis by enhancing the expression of VDAC2 channels and reducing the expression of Nedd4 E3 ubiquitin ligase, leading to lipid peroxidation and ROS production. The results suggested that RF-A has potential as a novel breast cancer treatment through its regulation of the mitochondrial VDAC2 and Nedd4 pathways., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Three new biflavones, apigenin-(3',8″)-chrysin ( 1 ), (2 S )-2,3-Dihydroametoflavone 5,4'-dimethyl ether ( 2 ), and (2 S )-5″,7″-Dihydroxy-2″-phenoxychromonyl-(4'″,3')-naringenin ( 3 ), together with seven known biflavones ( 4-10 ) were isolated from the 75% EtOH extract of Selaginella doederleinii . The structures of new compounds were established by application of spectroscopic methods, including 1D and 2D NMR, HRMS, and CD measurements. In addition, all new compounds were evaluated for their cytotoxic potential against three human cancer cell lines A549, MCF-7, and SMMC-7721 in vitro . Compound 2 exhibited potent cytotoxic activity with IC 50 values ranging from 6.35 to 10.18 μM.

The early vascular plants in the genus Selaginella , which is the sole genus of the Selaginellaceae family, have an important place in evolutionary history, along with ferns, as such plants are valuable resources for deciphering plant evolution. In this study, we sequenced and assembled the plastid genome (plastome) sequences of two Selaginella tamariscina individuals, as well as Selaginella stauntoniana and Selaginella involvens . Unlike the inverted repeat (IR) structures typically found in plant plastomes, Selaginella species had direct repeat (DR) structures, which were confirmed by Oxford Nanopore long-read sequence assembly. Comparative analyses of 19 lycophytes, including two Huperzia and one Isoetes species, revealed unique phylogenetic relationships between Selaginella species and related lycophytes, reflected by structural rearrangements involving two rounds of large inversions that resulted in dynamic changes between IR and DR blocks in the plastome sequence. Furthermore, we present other uncommon characteristics, including a small genome size, drastic reductions in gene and intron numbers, a high GC content, and extensive RNA editing. Although the 16 Selaginella species examined may not fully represent the genus, our findings suggest that Selaginella plastomes have undergone unique evolutionary events yielding genomic features unparalleled in other lycophytes, ferns, or seed plants.

Selaginella P. Beauv. is a group of vascular plants in the family Selaginellaceae Willk., found worldwide and numbering more than 700 species, with some used as foods and medicines. The aim of this paper was to compare methanolic (MeOH) and dichloromethane (DCM) extracts of eight Selaginella species on the basis of their composition and biological activities. Six of these Selaginella species are underinvestigated. Using ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) analysis, we identified a total of 193 compounds among the tested Selaginella species, with flavonoids predominating. MeOH extracts recovered more constituents that were detected, including selaginellins, the occurrence of which is only typical for this plant genus. Of all the tested species, Selaginella apoda contained the highest number of identified selaginellins. The majority of the compounds were identified in S. apoda , the fewest compounds in Selaginella cupressina . All the tested species demonstrated antioxidant activity using oxygen radical absorption capacity (ORAC) assay, which showed that MeOH extracts had higher antioxidant capacity, with the half maximal effective concentration (EC 50 ) ranging from 12 ± 1 ( Selaginella myosuroides ) to 124 ± 2 ( Selaginella cupressina ) mg/L. The antioxidant capacity was presumed to be correlated with the content of flavonoids, (neo)lignans, and selaginellins. Inhibition of acetylcholinesterase (AChE) was mostly discerned in DCM extracts and was only exhibited in S. myosuroides , S. cupressina , Selaginella biformis , and S. apoda extracts with the half maximal inhibitory concentration (IC 50 ) in the range of 19 ± 3 to 62 ± 1 mg/L. Substantial cytotoxicity against cancer cell lines was demonstrated by the MeOH extract of S. apoda , where the ratio of the IC 50 HEK (human embryonic kidney) to IC 50 HepG2 (hepatocellular carcinoma) was 7.9 ± 0.2. MeOH extracts inhibited the production of nitrate oxide and cytokines in a dose-dependent manner. Notably, S. biformis halved the production of NO, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 at the following concentrations: 105 ± 9, 11 ± 1, and 10 ± 1 mg/L, respectively. Our data confirmed that extracts from Selaginella species exhibited cytotoxicity against cancer cell lines and AChE inhibition. The activity observed in S. apoda was the most promising and is worth further exploration.

Plastids and mitochondria are endosymbiotic organelles that store genetic information. The genomes of these organelles generally exhibit contrasting patterns regarding genome architecture and genetic content. However, they have similar genetic features in Selaginellaceae, and little is known about what causes parallel evolution. Here, we document the multipartite plastid genomes (plastomes) and the highly divergent mitochondrial genomes (mitogenomes) from spikemoss obtained by combining short- and long-reads. The 188-kb multipartite plastome has three ribosomal operon copies in the master genomic conformation, creating the alternative subgenomic conformation composed of 110- and 78-kb subgenomes. The long-read data indicated that the two different genomic conformations were present in almost equal proportions in the plastomes of Selaginella nipponica. The mitogenome of S. nipponica was assembled into 27 contigs with a total size of 110 kb. All contigs contained directly arranged repeats at both ends, which introduced multiple conformations. Our results showed that plastomes and mitogenomes share high tRNA losses, GC-biased nucleotides, elevated substitution rates and complicated organization. The exploration of nuclear-encoded organelle DNA replication, recombination and repair proteins indicated that, several single-targeted proteins, particularly plastid-targeted recombinase A1, have been lost in Selaginellaceae; conversely, the dual-targeted proteins remain intact. According to the reported function of recombinase A1, we propose that the plastomes of spikemoss often fail to pair homologous sequences during recombination, and the dual-targeted proteins play a key role in the convergent genetic features of plastomes and mitogenomes. Our results provide a distinctive evolutionary pattern of the organelle genomes in Selaginellaceae and evidence of their convergent evolution., (© 2020 Society for Experimental Biology and John Wiley & Sons Ltd.)

Background: Desiccation tolerant Selaginella species evolved to survive extreme environmental conditions. Studies to determine the mechanisms involved in the acquisition of desiccation tolerance (DT) have focused on only a few Selaginella species. Due to the large diversity in morphology and the wide range of responses to desiccation within the genus, the understanding of the molecular basis of DT in Selaginella species is still limited., Results: Here we present a reference transcriptome for the desiccation tolerant species S. sellowii and the desiccation sensitive species S. denticulata. The analysis also included transcriptome data for the well-studied S. lepidophylla (desiccation tolerant), in order to identify DT mechanisms that are independent of morphological adaptations. We used a comparative approach to discriminate between DT responses and the common water loss response in Selaginella species. Predicted proteomes show strong homology, but most of the desiccation responsive genes differ between species. Despite such differences, functional analysis revealed that tolerant species with different morphologies employ similar mechanisms to survive desiccation. Significant functions involved in DT and shared by both tolerant species included induction of antioxidant systems, amino acid and secondary metabolism, whereas species-specific responses included cell wall modification and carbohydrate metabolism., Conclusions: Reference transcriptomes generated in this work represent a valuable resource to study Selaginella biology and plant evolution in relation to DT. Our results provide evidence of convergent evolution of S. sellowii and S. lepidophylla due to the different gene sets that underwent selection to acquire DT.

Two new abietane diterpenoids, (3S,5R,10S)-3-hydroxy-12-O-demethyl-11-deoxy-19(4→3)-abeo-cryptojaponol, 12,19-dihydroxyabieta-8,11,13-trien-7-one, were isolated from Selaginella moellendorffii Hieron., together with one known abietane diterpenoid and four known tetracyclic triterpenoids. Their structures were characterized by their 1D- and 2D-NMR, ECD and mass spectral studies. All compounds were tested for their inhibitory effects on proliferation of three human cancer cells (human non-small-cell lung carcinoma cell lines A549 and human breast adenocarcinoma cell lines MDA-MB-231 and MCF-7) in vitro. Among them, three compounds displayed modest cytotoxic activities against the above three human cancer cell lines with IC 50 values ranging from 16.28 to 40.67 μM., (© 2020 Wiley-VHCA AG, Zurich, Switzerland.)

Three new neolignan derivatives ( 1-3 ), together with three known isolariciresinol derivatives ( 4-6 ) were isolated from Selaginella picta . Their structures were elucidated by spectroscopic methods (1D/2D NMR, HRESIMS and CD). All isolated compounds were assayed on the neuroprotective activity against the injury of HT-22 cells induced by L-Glutamate in vitro . All compounds displayed potent protective effect on HT-22 cells.

Mannans are an abundant cell wall polysaccharide in bryophytes, seedless vascular plants and gymnosperms. A previous study has shown that mannan acetylation in Arabidopsis and konjac is mediated by mannan O-acetyltransferases belonging to the Domain of Unknown Function (DUF) 231 family. However, little is known about the acetylation patterns of mannans in bryophytes and seedless vascular plants, and the evolutionary origin of mannan O-acetyltransferases in land plants has not yet been studied. Phylogenetic analysis of the DUF231 family revealed that DUF231 members were present in the charophycean green algae and evolved to form overlapped and divergent phylogenetic groups in different taxa of land plants. Acetyltransferase activity assays of recombinant proteins demonstrated that a number of group II DUF231 members from moss, Selaginella, pine, spruce, rice and poplar were mannan 2-O- and 3-O-acetyltransferases, whereas the two group I DUF231 members from the alga Klebsormidium nitens were not. Structural analysis of mannans from moss and Selaginella showed they were composed of mannosyl and glucosyl residues and the mannosyl residues were acetylated at O-2 and O-3. These findings indicate that although the DUF231 genes originated in algae, their recruitment as mannan O-acetyltransferases probably occurred in bryophytes, and the biochemical functions of these O-acetyltransferases are evolutionarily conserved throughout land plants., (© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.)

Leaves constitute the main photosynthetic plant organ and even though their importance is not debated, the origin and development of leaves still is. The leaf developmental network has been elucidated for angiosperms, from genes controlling leaf initiation, to leaf polarity and shape. There are four KANADI ( KAN ) paralogs in Arabidopsis thaliana needed for organ polarity with KAN1 and KAN2 specifying abaxial leaf identity. Yet, studies of this gene lineage outside angiosperms are required to better understand the evolutionary patterns of leaf development and the role of KAN homologs. We studied the evolution of KAN genes across vascular plants and their expression by in situ hybridization in the fern, Equisetum hyemale and the lycophyte Selaginella moellendorffii . Our results show that the expression of KAN genes in leaves is similar between ferns and angiosperms. However, the expression patterns observed in the lycophyte S. moellendorffii are significantly different compared to all other vascular plants, suggesting that the KAN function in leaf polarity is likely only conserved across ferns, gymnosperms, and angiosperms. This study indicates that mechanisms for leaf development are different in lycophytes compared to other vascular plants.

Background and Aims: Tropical understorey plant communities are highly diverse and characterized by variable resource availability, especially light. Plants in these competitive environments must carefully partition resources to ensure ecological and evolutionary success. One mechanism of effective resource partitioning is the optimization of functional traits to enhance competition in highly heterogeneous habitats. Here, we surveyed the ecophysiology of two early lineage vascular plant groups from a tropical forest understorey: Selaginella (a diverse lineage of lycophytes) and ferns., Methods: In a lowland rain forest in Costa Rica, we measured a suite of functional traits from seven species of Selaginella and six fern species. We evaluated species microclimate and habitat; several photosynthetic parameters; carbon, nitrogen and phosphorus content; chlorophyll concentration; leaf mass per area (LMA); and stomatal size and density. We then compare these two plant lineages and search for relationships between key functional parameters that already exist on a global scale for angiosperms., Key Results: Convergence of trait function filtered Selaginella species into different habitats, with species in heavily shaded environments having higher chlorophyll concentrations and lower light compensation points compared with open habitats. Alternatively, lower foliar nitrogen and higher stomatal densities were detected in species occupying these open habitats. Selaginella species had denser and smaller stomata, lower LMA and lower foliar nutrient content than ferns, revealing how these plant groups optimize ecophysiological function differently in tropical forest floors., Conclusions: Our findings add key pieces of missing evidence to global explorations of trait patterns that define vascular plant form and function, which largely focus on seed plants. Broadly predictable functional trait relationships were detected across both Selaginella and ferns, similar to those of seed plants. However, evolutionary canalization of microphyll leaf development appears to have driven contrasting, yet successful, ecophysiological strategies for two coexisting lineages of extant homosporous vascular plants., (© The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Both direct repeats (DR) and inverted repeats (IR) are documented in the published plastomes of Selaginella species indicating the unusual and diverse plastome structure in the family Selaginellaceae. In this study, we newly sequenced complete plastomes of seven species from five main lineages of Selaginellaceae and also resequenced three species (Selaginella tamariscina, Selaginella uncinata, and Selaginella moellendorffii) to explore the evolutionary trajectory of Selaginellaceae plastomes. Our results showed that the plastomes of Selaginellaceae vary remarkably in size, gene contents, gene order, and GC contents. Notably, both DR and IR structures existed in the plastomes of Selaginellaceae with DR structure being an ancestral state. The occurrence of DR structure was at ∼257 Ma and remained in most subgenera of Selaginellaceae, whereas IR structure only reoccurred in Selaginella sect. Lepidophyllae (∼143 Ma) and Selaginella subg. Heterostachys (∼19 Ma). The presence of a pair of large repeats psbK-trnQ, together with DR/IR region in Selaginella bisulcata, Selaginella pennata, S. uncinata, and Selaginella hainanensis, could frequently mediate diverse homologous recombination and create approximately equal stoichiometric isomers (IR/DR-coexisting) and subgenomes. High proportion of repeats is presumably responsible for the dynamic IR/DR-coexisting plastomes, which possess a lower synonymous substitution rate (dS) compared with DR-possessing and IR-possessing plastomes. We propose that the occurrence of DR structure, together with few repeats, is possibly selected to keep the stability of plastomes and the IR/DR-coexisting plastomes also reached an equilibrium in plastome organization through highly efficient homologous recombination to maintain stability., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Angiosperms develop intensively branched root systems that are accommodated with the high capacity to produce plenty of new lateral roots throughout their life-span. Root branching can be dynamically regulated in response to edaphic conditions and provides the plants with a soil-mining potential. This highly specialized branching capacity has most likely been key in the colonization success of the present flowering plants on our planet. The initiation, formation and outgrowth of branching roots in Angiosperms are dominated by the plant hormone auxin. Upon auxin treatment root branching through the formation of lateral roots can easily be induced. In this study, we questioned whether this strong branching-inducing action of auxin is part of a conserved mechanism that was already active in the earliest diverging lineage of vascular plants with roots. In Selaginella, an extant representative species of this early clade of root forming plants, components of the canonical auxin signaling pathway are retrieved in its genome. Although we observed a clear physiological response and an indirect effect on root branching, we were not able to directly induce root branching in this species by application of different auxins. We conclude that the structural and developmental difference of the Selaginella root, which branches via bifurcation of the root meristem, or the absence of an auxin-mediated root development program, is most likely causative for the absence of an auxin-induced branching mechanism.

In the present study, the surface ornamentations of both megaspores and microspores of 20 species of Selaginella were studied using scanning electron microscopy. The results of the present study showed that the megaspore surface ornamentations are complementary to the corresponding microspore surface ornamentations. In detail, reticulate surface ornamentation of megaspores is complementary to granulate and baculate ornamentations of microspores; verrucate ornamentation of megaspores is complementary to scabrate ornamentation of microspores; granulate ornamentation of megaspores is complementary to verrucate-rugulate or verrucate ornamentations of microspores; verrucate-rugulate ornamentation of megaspores is complementary to spinulate, verrucate, or verrucate-rugulate ornamentations of microspores; tuberculate ornamentation of megaspores is complementary to lamellate, tuberculate or verrucate ornamentations of microspores. Complementary ornamentation between megaspores and microspores allows microspores to adhere to megaspores. Our observations support the "synaptospory" hypothesis, that is, spore surface ornamentation plays a part in keeping or bringing spores together during their dispersal in the pteridophytes., (© 2018 Wiley Periodicals, Inc.)

Mosses, liverworts, hornworts and lycophytes represent transition stages between the aquatic to terrestrial/land plants. Several morphological and adaptive novelties driven by genomic components including emergence and expansion of new or existing gene families have played a critical role during and after the transition, and contributed towards successful colonization of terrestrial ecosystems. It is crucial to decipher the evolutionary transitions and natural selection on the gene structure and function to understand the emergence of phenotypic and adaptive diversity. Plants at the "transition zone", between aquatic and terrestrial ecosystem, are also the most vulnerable because of climate change and may contain clues for successful mitigation of the challenges of climate change. Identification and comparative analyses of such genetic elements and gene families are few in mosses, liverworts, hornworts and lycophytes. Ovate family proteins (OFPs) are plant-specific transcriptional repressors and are acknowledged for their roles in important growth and developmental processes in land plants, and information about the functional aspects of OFPs in early land plants is fragmentary. As a first step towards addressing this gap, a comprehensive in silico analysis was carried out utilizing publicly available genome sequences of Marchantia polymorpha (Mp), Physcomitrella patens (Pp), Selaginella moellendorffii (Sm) and Sphagnum fallax (Sf). Our analysis led to the identification of 4 MpOFPs, 19 PpOFPs, 6 SmOFPs and 3 SfOFPs. Cross-genera analysis revealed a drastic change in the structure and physiochemical properties in OFPs suggesting functional diversification and genomic plasticity during the evolutionary course. Knowledge gained from this comparative analysis will form the framework towards deciphering and dissection of their developmental and adaptive role/s in early land plants and could provide insights into evolutionary strategies adapted by land plants.

Three new compounds, pictalignans A (1), B (2), C (3), along with three known analogues, syringaresinol (4), 3,3',5-trimethoxy-4',7-epoxy-8,5'-neoligan-4',9,9'-triol (5), 4,9-dihydroxy-4',7-epoxy-8',9'-dinor-8,5'-neolignan-7'-oic acid (6) were isolated from the 75% aqueous ethanol extract of Selaginella picta. Their structures were established by physicochemical properties and spectroscopic methods, and absolute configurations of new compounds were elucidated by experimental and calculated ECD spectra. Compounds 1-3 are neolignans with additional one or two C 6 -C 3 structural units attached to hydroxypropyl group, which are extremely rare in nature. All new compounds exhibited moderate protective effect against the injury of HT-22 cells induced by L-Glutamate in vitro, and compound 1 showed better protective effect than positive drug with the concentrations of 10 μM to 15 μM., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background and Aims: The division of resource investment between male and female functions is poorly known for land plants other than angiosperms. The ancient lycophyte genus Selaginella is similar in some ways to angiosperms (in heterospory and in having sex allocation occur in the sporophyte generation, for example) but lacks the post-fertilization maternal investments that angiosperms make via fruit and seed tissues. One would therefore expect Selaginella to have sex allocation values less female-biased than in flowering plants and closer to the theoretical prediction of equal investment in male and female functions. Nothing is currently known of sex allocation in the genus, so even the simplest predictions have not been tested., Methods: Volumetric measurements of microsporangial and megasporangial investment were made in 14 species of Selaginella from four continents. In five of these species the length of the main above-ground axis of each plant was measured to determine whether sex allocation is related to plant size., Key Results: Of the 14 species, 13 showed male-biased allocations, often extreme, in population means and among the great majority of individual plants. There was some indication from the five species with axis length measurements that relative male allocation might be related to the release height of spores, but this evidence is preliminary., Conclusions: Sex allocation in Selaginella provides a phylogenetic touchstone showing how the innovations of fruit and seed investment in the angiosperm life cycle lead to typically female-biased allocations in that lineage. Moreover, the male bias we found in Selaginella requires an evolutionary explanation. The bias was often greater than what would occur from the mere absence of seed and fruit investments, and thus poses a challenge to sex allocation theory. It is possible that differences between microspores and megaspores in their dispersal ecology create selective effects that favour male-biased sexual allocation. This hypothesis remains tentative., (© The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The Selaginella rhizophore is a unique and enigmatic organ whose homology with roots, shoots, or neither of the two remains unresolved. Nevertheless, rhizophore-like organs have been documented in several fossil lycophytes. Here we test the homology of these organs through comparisons with the architecture of rhizophore vascularization in Selaginella. We document rhizophore vascularization in nine Selaginella species using cleared whole-mounts and histological sectioning combined with three-dimensional reconstruction. Three patterns of rhizophore vascularization are present in Selaginella and each is comparable to those observed in rhizophore-like organs of fossil lycophytes. More compellingly, we found that all Selaginella species sampled exhibit tracheids that arc backward from the stem and side branch into the rhizophore base. This tracheid curvature is consistent with acropetal auxin transport previously documented in the rhizophore and is indicative of the redirection of basipetal auxin from the shoot into the rhizophore during development. The tracheid curvature observed in Selaginella rhizophores provides an anatomical fingerprint for the patterns of auxin flow that underpin rhizophore development. Similar tracheid geometry may be present and should be searched for in fossils to address rhizophore homology and the conservation of auxin-related developmental mechanisms from early stages of lycophyte evolution., (© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.)

A new neolignan, selamoellenin A (1), was isolated from the whole plants of Selaginella moellendorffii Hieron. The structure was elucidated on the basis of comprehensive spectroscopic methods (1D/2D NMR and HRMS). Compound 1 was evaluated for its protective effect against high glucose-induced human umbilical vein endothelial cells (HUVECs) damage in vitro.

Eight triflavonoids, selagintriflavonoids A-H, were isolated from whole herbs of Selaginella doederleinii. The structures of compounds selagintriflavonoids A-C consisted of three naringenin units, whereas those of selagintriflavonoids D-H consisted of apigenin and two naringenin moieties. The structures and absolute configurations of the compounds were determined based on NMR, HRESIMS, and experimental and calculated electronic circular dichroism (ECD) data. The ability of the compounds to inhibit β-secretase (BACE1) was also evaluated. All compounds exhibited BACE1 inhibition with IC 50 values ranging from 0.75 to 46.99 μM. Selagintriflavonoid A exhibited the strongest inhibition (0.75 μM) and is thus a promising compound for treating Alzheimer's disease., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Six new flavonoids, seladoeflavones A-F (1-6), were isolated from the whole herbs of Selaginella doederleinii, together with one known flavonoid (7). Their structures including absolute configuration were characterized on the basis of extensive spectroscopic methods including NMR, HRMS, and electronic circular dichroism (ECD). All compounds consist of an aryl substituent at the C-3' position of naringenin or apigenin skeletons, and compounds 1 and 6 were identified as R configurations, which are uncommonly encountered in nature. A possible biosynthetic pathway was postulated. In addition, bioassay of the isolates revealed that 5-7 exhibited moderate cytotoxicity against three human cancer cell lines NCI-H460, A549, and K562 in vitro with IC 50 values ranging from 8.17 to 18.66μM., (Copyright © 2016. Published by Elsevier B.V.)

Premise of the Study: The cosmopolitan lycophyte family Selaginellaceae, dating back to the Late Devonian-Early Carboniferous, is notorious for its many species with a seemingly undifferentiated gross morphology. This morphological stasis has for a long time hampered our understanding of the evolutionary history of the single genus Selaginella. Here we present a large-scale phylogenetic analysis of Selaginella, and based on the resulting phylogeny, we discuss morphological evolution in the group., Methods: We sampled about one-third of the approximately 750 recognized Selaginella species. Evolutionary relationships were inferred from both chloroplast (rbcL) and single-copy nuclear gene data (pgiC and SQD1) using a Bayesian inference approach. The morphology of the group was studied and important features mapped onto the phylogeny., Key Results: We present an overall well-supported phylogeny of Selaginella, and the phylogenetic positions of some previously problematic taxa (i.e., S. sinensis and allies) are now resolved with strong support. We show that even though the evolution of most morphological characters involves reversals and/or parallelisms, several characters are phylogenetically informative. Seven major clades are identified, which each can be uniquely diagnosed by a suite of morphological features. There is value in morphology after all!, Conclusions: Our hypothesis of the evolutionary relationships of Selaginella is well founded based on DNA sequence data, as well as morphology, and is in line with previous findings. It will serve as a firm basis for further studies on Selaginella with respect to, e.g., the poorly known alpha taxonomy, as well as evolutionary questions such as historical biogeographic reconstructions., (© 2016 Weststrand and Korall. Published by the Botanical Society of America. This work is licensed under a Creative Commons Attribution License (CC-BY 4.0).)

The present study is to investigate the chemical constituents of the whole plants of Selaginella uncinata. A new flavonoid was isolated from the 75% ethanol extract of Selaginella uncinata by column chromatographies over macroporous resin, silica gel, Sephadex LH-20 and prep-HPLC. The structure was elucidated as 8-[4-(carboxyl)phenoxy]-5,4'-dihydroxy-7-methoxyflavanone (1) and named unciflacone G., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Chinese Pharmaceutical Association.)

Xylan is a major cross-linking hemicellulose in secondary walls of vascular tissues, and the recruitment of xylan as a secondary wall component was suggested to be a pivotal event for the evolution of vascular tissues. To decipher the evolution of xylan structure and xylan biosynthetic genes, we analyzed xylan substitution patterns and characterized genes mediating methylation of glucuronic acid (GlcA) side chains in xylan of the model seedless vascular plant, Selaginella moellendorffii, and investigated GT43 genes from S. moellendorffii and the model non-vascular plant, Physcomitrella patens, for their roles in xylan biosynthesis. Using nuclear magentic resonance spectroscopy, we have demonstrated that S. moellendorffii xylan consists of β-1,4-linked xylosyl residues subsituted solely with methylated GlcA residues and that xylans from both S. moellendorffii and P. patens are acetylated at O-2 and O-3. To investigate genes responsible for GlcA methylation of xylan, we identified two DUF579 genes in the S. moellendorffii genome and showed that one of them, SmGXM, encodes a glucuronoxylan methyltransferase capable of adding the methyl group onto the GlcA side chain of xylooligomers. Furthermore, we revealed that the two GT43 genes in S. moellendorffii, SmGT43A and SmGT43B, are functional orthologs of the Arabidopsis xylan backbone biosynthetic genes IRX9 and IRX14, respectively, indicating the evolutionary conservation of the involvement of two functionally non-redundant groups of GT43 genes in xylan backbone biosynthesis between seedless and seed vascular plants. Among the five GT43 genes in P. patens, PpGT43A was found to be a functional ortholog of Arabidopsis IRX9, suggesting that the recruitment of GT43 genes in xylan backbone biosynthesis occurred when non-vascular plants appeared on land., (© The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

The haploid nuclear genome size (1C DNA) of vascular land plants varies over several orders of magnitude. Much of this observed diversity in genome size is due to the proliferation and deletion of transposable elements. To date, all vascular land plant lineages with extremely small nuclear genomes represent recently derived states, having ancestors with much larger genome sizes. The Selaginellaceae represent an ancient lineage with extremely small genomes. It is unclear how small nuclear genomes evolved in Selaginella We compared the rates of nuclear genome size evolution in Selaginella and major vascular plant clades in a comparative phylogenetic framework. For the analyses, we collected 29 new flow cytometry estimates of haploid genome size in Selaginella to augment publicly available data. Selaginella possess some of the smallest known haploid nuclear genome sizes, as well as the lowest rate of genome size evolution observed across all vascular land plants included in our analyses. Additionally, our analyses provide strong support for a history of haploid nuclear genome size stasis in Selaginella Our results indicate that Selaginella, similar to other early diverging lineages of vascular land plants, has relatively low rates of genome size evolution. Further, our analyses highlight that a rapid transition to a small genome size is only one route to an extremely small genome., (© The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.)

Five new carboxymethyl flavonoids named 5-carboxymethyl-3', 4', 7-trihydroxyflavone (1), (2S)- 5-carboxymethyl-3', 4', 7-trihydroxyflavonone (2a), (2R)-5-carboxymethyl-3', 4', 7-trihydroxyflavonone (2b), (2S)-5-carboxymethyl-4', 7-dihydroxyflavonone (3), 5- carbomethoxymethyl-4', 7-dihydroxyflavone (4), and a new chromone named 5-carboxymethyl-7-hydroxychromone (5), together with two known compounds 5-carboxymethyl-4'-hydroxyflavone-7-O-β-d-glucopyranoside (6), 5-carboxymethyl-4', 7-dihydroxyflavone (7) were isolated from Selaginella moellendorffii Hieron. Their structures including absolute configuration were elucidated by extensive spectroscopic methods and experimental electronic circular dichroism (ECD) spectra. What's worth mentioning is that a carboxymethyl substituent appeared at the C-5 position of all isolated compounds, only recently discovered in genus Selaginella. Compounds 2a and 2b were identified as a pair of chiral isomers; compound 5 was discovered as the first chromone comprising a carboxymethyl side chain. Furthermore, all compounds were evaluated for their antibacterial activities against various Gram-positives and Gram-negatives, and compared to the reference drugs amoxicillin and norfloxacin. As a result, compounds 3 and 4 exhibited as potent antimicrobial agents with a broad spectrum, and compound 5 appeared as the most promising one to combat Gram-positives., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Two new flavonoids, uncinataflavones A (1) and B (2), along with one known compound 6-(5-carboxyl-2-methoxyphenyl)-apigenin (3), were isolated from Selaginella uncinata (Desv.) Spring. All these compounds belong to apigenin derivatives with aryl substituents at C-6 position. The structures of new compounds were elucidated on the basis of comprehensive spectroscopic analyses (UV, IR, 1D, and 2D NMR as well as HR-ESI-MS).

Six new flavonoids, involvenflavones A-F (1-6), were isolated from Selaginella involven. Their structures were elucidated based on UV, IR, 1D and 2D NMR as well as HR-ESI-MS techniques. All compounds belong to apigenin derivatives with 3'-aryl substituent. This is the first report of the apigenin derivatives with 3'-aryl substituent from nature resources. These compounds also exhibited a potent effect against the injury of human umbilical vein endothelial cell (HUVECs) induced by high concentrations of glucose in vitro., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Six new flavonoids, unciflavones A-F (1-6), have been isolated from medicinal plant Selaginella uncinata (Desv.) Spring. Their structures were established on the basis of extensive NMR analysis including 1D NMR ((1)H, (13)C and DEPT) and 2D NMR (COSY, HSQC, HMBC) experiments as well as HRESIMS analysis. All compounds possess exceptional structural features with an aryl substituent at the C-8 position, which are uncommonly encountered in natural resources and firstly reported in genus Selaginella., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: Selaginella species are resurrection plants, which are known, possess various molecular bioactivities depending on species, but only a few species have been detailed observe in the advanced research., Objective: The objective of the following study is to compare the chemical profiles of different species of Selaginella and to investigate cytotoxicity and induction of apoptosis activities of some species of Selaginella., Materials and Methods: The high-performance liquid chromatography (HPLC) method was developed for chemical analysis. Ethyl acetate, ethanol and water-soluble extracts from seven Selaginella species were submitted to 3-(4,5-dimenthyl thizol-2-yl)-2,5-diphenyl tetrazolium bromide assay, flow cytometry, deoxyribonucleic acid (DNA) laddering analysis and caspase-3 expression using Bel-7402, HT-29 and HeLa cells., Results: The HPLC analysis revealed two major common peaks, which were identified as amentoflavone and robustaflavone and another three main peaks in their chromatograms. The results showed that S. labordei, Selaginella tamariscina and Selaginella uncinata had relatively stronger activities on Bel-7402 and HeLa cells and Selaginella moellendorfii had moderate antiproliferation activities, but Selaginella remotifolia and Selaginella pulvinata had almost no inhibitory activities. The main active components were in the ethyl acetate extracts which had abundant biflavonoids. The effects of these extracts on cell proliferation and apoptosis in different cells were not the same, they were more apparent on HeLa cells than on HT-29 cells. The assay of DNA laddering analysis and caspase-3 expression further confirmed that inducing cell apoptosis was one of antitumor mechanisms and antitumor activities of Selaginella species were related to apoptosis induced by caspase family., Conclusion: S. labordei, S. tamariscina and S. uncinata would be potential antitumor agents.

Background: Selaginella (Selaginella moellendorffii) is a lycophyte which diverged from other vascular plants approximately 410 million years ago. As the first reported non-seed vascular plant genome, Selaginella genome data allow comparative analysis of genetic changes that may be associated with land plant evolution. Proteomics investigations on this lycophyte model have not been extensively reported. Phosphorylation represents the most common post-translational modifications and it is a ubiquitous regulatory mechanism controlling the functional expression of proteins inside living organisms., Results: In this study, polyethylene glycol fractionation and immobilized metal ion affinity chromatography were employed to isolate phosphopeptides from wild-growing Selaginella. Using liquid chromatography-tandem mass spectrometry analysis, 1593 unique phosphopeptides spanning 1104 non-redundant phosphosites with confirmed localization on 716 phosphoproteins were identified. Analysis of the Selaginella dataset revealed features that are consistent with other plant phosphoproteomes, such as the relative proportions of phosphorylated Ser, Thr, and Tyr residues, the highest occurrence of phosphosites in the C-terminal regions of proteins, and the localization of phosphorylation events outside protein domains. In addition, a total of 97 highly conserved phosphosites in evolutionary conserved proteins were identified, indicating the conservation of phosphorylation-dependent regulatory mechanisms in phylogenetically distinct plant species. On the other hand, close examination of proteins involved in photosynthesis revealed phosphorylation events which may be unique to Selaginella evolution. Furthermore, phosphorylation motif analyses identified Pro-directed, acidic, and basic signatures which are recognized by typical protein kinases in plants. A group of Selaginella-specific phosphoproteins were found to be enriched in the Pro-directed motif class., Conclusions: Our work provides the first large-scale atlas of phosphoproteins in Selaginella which occupies a unique position in the evolution of terrestrial plants. Future research into the functional roles of Selaginella-specific phosphorylation events in photosynthesis and other processes may offer insight into the molecular mechanisms leading to the distinct evolution of lycophytes.

In a recent addendum, Oren Tzfadia and Gad Galili (PSB 2014; 9:e26732) showed that several Arabidopsis exocyst subunits possess consensus Atg8-interacting motifs (AIMs), which may mediate their interaction with the autophagy-associated Atg8 protein, providing thus a mechanistic base for participation of exocyst (sub)complexes in autophagy. However, the bioinformatically identified AIMs are short peptide motifs that may occur by chance. We thus performed an exhaustive search in a large collection of plant exocyst-derived sequences from our previous bioinformatic study and found that AIMs are over-represented among exocyst subunits of all lineages examined, including moss and club moss, compared with a representative sample of the Arabidopsis proteome. This is consistent with the proposed exocyst AIMs being biologically meaningful and evolutionarily ancient. Moreover, among the numerous EXO70 paralogs, the monocot-specific EXO70F clade appears to be exempt from the general AIM enrichment, suggesting a modification of the autophagy connection in a subset of exocyst variants.

Premise of the Study: Several members of Selaginella are renowned for their ability to survive extreme drought and "resurrect" when conditions improve. Many of these belong to subgenus Tetragonostachys, a group of ∼45 species primarily found in North and Central America, with substantial diversity in the Sonoran and Chihuahuan Deserts. We evaluated the monophyly and the age of subgenus Tetragonostachys and assess how drought tolerance contributed to the evolution of this clade., Methods: Our study included most Tetragonostachys species, using plastid and nuclear sequences, fossil and herbarium records, and climate variables to describe the species diversity, phylogenetic relationships, divergence times, and climatic niche evolution in the subgenus., Key Results: We found that subgenus Tetragonostachys forms a monophyletic group sister to Selaginella lepidophylla and may have diverged from other Selaginella because of a Gondwanan-Laurasian vicariance event ca. 240 mya. The North American radiation of Tetragonostachys appears to be much more recent and to have occurred during the Early Cretaceous-late Paleocene interval. We identified two significant and nested ecological niche shifts during the evolution of Tetragonostachys associated with extreme drought tolerance and a more recent shift to cold climates. Our analyses suggest that drought tolerance evolved in the warm deserts of southwest North America and may have been advantageous for colonization of cold and dry boreal climates., Conclusions: Our investigation provides a foundation for future research addressing the genomics of ecological niche evolution and the potential role of reticulate evolution in Selaginella subgenus Tetragonostachys.

Early plants began colonizing the terrestrial earth approximately 450 million years ago. Their success on land has been partially attributed to the evolution of specialized metabolic systems from core metabolic pathways, the former yielding structurally and functionally diverse chemicals to cope with a myriad of biotic and abiotic ecological pressures. Over the past two decades, functional genomics, primarily focused on flowering plants, has begun cataloging the biosynthetic players underpinning assorted classes of plant specialized metabolites. However, the molecular mechanisms enriching specialized metabolic pathways during land plant evolution remain largely unexplored. Selaginella is an extant lycopodiophyte genus representative of an ancient lineage of tracheophytes. Notably, the lycopodiophytes diverged from euphyllophytes over 400 million years ago. The recent completion of the whole-genome sequence of an extant lycopodiophyte, S. moellendorffii, provides new genomic and biochemical resources for studying metabolic evolution in vascular plants. 400 million years of independent evolution of lycopodiophytes and euphyllophytes resulted in numerous metabolic traits confined to each lineage. Surprisingly, a cadre of specialized metabolites, generally accepted to be restricted to seed plants, have been identified in Selaginella. Initial work suggested that Selaginella lacks obvious catalytic homologs known to be involved in the biosynthesis of well-studied specialized metabolites in seed plants. Therefore, these initial functional analyses suggest that the same chemical phenotypes arose independently more commonly than anticipated from our conventional understanding of the evolution of metabolism. Notably, the emergence of analogous and homologous catalytic machineries through convergent and parallel evolution, respectively, seems to have occurred repeatedly in different plant lineages.

Organelle genomes show remarkable variation in architecture and coding content, yet their nucleotide composition is relatively unvarying across the eukaryotic domain, with most having a high adenine and thymine (AT) content. Recent studies, however, have uncovered guanine and cytosine (GC)-rich mitochondrial and plastid genomes. These sequences come from a small but eclectic list of species, including certain green plants and animals. Here, I review GC-rich organelle DNAs and the insights they have provided into the evolution of nucleotide landscape. I emphasize that GC-biased mitochondrial and plastid DNAs are more widespread than once thought, sometimes occurring together in the same species, and suggest that the forces biasing their nucleotide content can differ both among and within lineages, and may be associated with specific genome architectural features and life history traits.

As heritage from early evolution, potassium (K(+)) is absolutely necessary for all living cells. It plays significant roles as stabilizer in metabolism and is important for enzyme activation, stabilization of protein synthesis, and neutralization of negative charges on cellular molecules as proteins and nucleic acids. Land plants even enlarged this spectrum of K(+) utilization after having gone ashore, despite the fact that K(+) is far less available in their new oligotrophic habitats than in sea water. Inevitably, plant cells had to improve and to develop unique transport systems for K(+) accumulation and distribution. In the past two decades a manifold of K(+) transporters from flowering plants has been identified at the molecular level. The recently published genome of the fern ally Selaginella moellendorffii now helps in providing a better understanding on the molecular changes involved in the colonization of land and the development of the vasculature and the seeds. In this article we present an inventory of K(+) transporters of this lycophyte and pigeonhole them together with their relatives from the moss Physcomitrella patens, the monocotyledon Oryza sativa, and two dicotyledonous species, the herbaceous plant Arabidopsis thaliana, and the tree Populus trichocarpa. Interestingly, the transition of green plants from an aqueous to a dry environment coincides with a dramatic reduction in the diversity of voltage-gated potassium channels followed by a diversification on the basis of one surviving K(+) channel class. The first appearance of K(+) release (K(out)) channels in S. moellendorffii that were shown in Arabidopsis to be involved in xylem loading and guard cell closure coincides with the specialization of vascular plants and may indicate an important adaptive step.