Fern Adiantum Capillus-veneris Research Articles

A phytochrome/phototropin chimeric photoreceptor promotes growth of fern gametophytes under limited light conditions.

Many ferns thrive even in low-light niches such as under an angiosperm forest canopy. However, the shade-adaptation strategy of ferns is not well understood. Phytochrome 3/neochrome (phy3/neo) is an unconventional photoreceptor, found in the fern Adiantum capillus-veneris, that controls both red- and blue-light-dependent phototropism and chloroplast photorelocation, which are believed to improve photosynthetic efficiency in ferns. Here we show that phy3/neo localizes not only at the plasma membrane but also in the nucleus. Since both phototropism and chloroplast photorelocation are mediated by membrane-associated phototropin photoreceptors, we speculated that nucleus-localized phy3/neo possesses a previously undescribed biological function. We reveal that phy3/neo directly interacts with Adiantum cryptochrome 3 (cry3) in the nucleus. Plant cryptochromes are blue-light receptors that transcriptionally regulate photomorphogenesis; therefore, phy3/neo may function via cry3 to synchronize light-mediated development with phototropism and chloroplast photorelocation to promote fern growth under low-light conditions. Furthermore, we demonstrate that phy3/neo regulates the expression of the Cyclin-like gene AcCyc1 and promotes prothallium expansion growth. These findings provide insight into the shade-adaptation strategy of ferns and suggest that phy3/neo plays a substantial role in the survival and growth of ferns during the tiny gametophytic stage under low-light conditions, such as those on the forest floor.

Limiting chemical parameters in soil and water controlling the presence of the fern Adiantum Capillus Veneris L. In South Sinai and Sharkia governorates in Egypt

Limiting chemical parameters in soil and water controlling the presence of the fern Adiantum Capillus Veneris L. In South Sinai and Sharkia governorates in Egypt

Refinements to light sources used to analyze the chloroplast cold-avoidance response over the past century

ABSTRACTChloroplasts alter their subcellular positions in response to ambient light and temperature conditions. This well-characterized light-induced response, which was first described nearly 100 years ago, is regulated by the blue-light photoreceptor, phototropin. By contrast, the molecular mechanism of low temperature-induced chloroplast relocation (i.e., the cold-avoidance response) was unexplored until its discovery in the fern Adiantum capillus-veneris in 2008. Because this response is also regulated by phototropin, it was thought to occur in a blue light-dependent manner. However, until recently, the blue light dependency of this response could not be examined due to the lack of a stable light source under cold conditions. We recently refined the light source to precisely control light intensity under cold conditions. Using this light source, we observed the blue light dependency of the cold-avoidance response in the liverwort Marchantia polymorpha and the phototropin2-mediated cold-avoidance response in the flowering plant Arabidopsis thaliana. Thus, this mechanism is evolutionarily conserved among land plants.

A Modified Approach for Axenic Cultivation of Spores of Fern Adiantum capillus-veneris L. with High Germination Rate.

Spores are the primary way of spread and reproduction for ferns, a clade of seed-free vascular plants. However, no detailed protocol for ferns spore cultivation has been reported yet. Here we provide a modified approach for axenic cultivation of fern Adiantum capillus-veneris L., based on Cao's and Li's method (Cao, et al., 2010; Li, et al., 2013). Our approach can be briefly divided into four steps: 1) collect spores; 2) sterilize the spores with 5% sodium hypochlorite solution and wash twice; 3) incubate the spores in liquid Knop's medium in the dark for five days; 4) cultivate the spores on Knop's plate medium. To increase the germination rate, we constrain the sterilization time under 25 min and add dark treatment step after spore sterilization. After these modifications, the germination rate raises from 2% to 25%.

Chloroplast aggregation during the cold-positioning response in the liverwort Marchantia polymorpha.

Under low-light conditions, chloroplasts localize along periclinal cell walls at temperatures near 20 °C, but they localize along anticlinal cell walls near 5 °C. This phenomenon is known as the cold-positioning response. We previously showed that chloroplasts move as aggregates rather than individually during the cold-positioning response in the fern Adiantum capillus-veneris. This observation suggested that chloroplasts physically interact with each other during the cold-positioning response. However, the physiological processes underlying chloroplast aggregation are unclear. In this report, we characterized chloroplast aggregation during the cold-positioning response in the liverwort Marchantia polymorpha. Confocal laser microscopy observations of transgenic liverwort plants expressing a fluorescent fusion protein that localizes to the chloroplast outer envelope membrane (OEP7-Citrine) showed that neighboring chloroplast membranes did not fuse during the cold-positioning response. Transmission electron microscopy analysis revealed that a distance of at least 10nm was maintained between neighboring chloroplasts during aggregation. These results indicate that aggregated chloroplasts do not fuse, but maintain a distance of at least 10nm from each other during the cold-positioning response.

Temperature-dependent signal transmission in chloroplast accumulation response.

Chloroplast photorelocation movement, well-characterized light-induced response found in various plant species from alga to higher plants, is an important phenomenon for plants to increase photosynthesis efficiency and avoid photodamage. The signal for chloroplast accumulation movement connecting the blue light receptor, phototropin, and chloroplasts remains to be identified, although the photoreceptors and the mechanism of movement via chloroplast actin filaments have now been revealed in land plants. The characteristics of the signal have been found; the speed of signal transfer is about 1µm min-1 and that the signal for the accumulation response has a longer life and is transferred a longer distance than that of the avoidance response. Here, to collect the clues of the unknown signal substances, we studied the effect of temperature on the speed of signal transmission using the fern Adiantum capillus-veneris and found the possibility that the mechanism of signal transfer was not dependent on the simple diffusion of a substance; thus, some chemical reaction must also be involved. We also found new insights of signaling substances, such that microtubules are not involved in the signal transmission, and that the signal could even be transmitted through the narrow space between chloroplasts and the plasma membrane.

A phytochrome/phototropin chimeric photoreceptor of fern functions as a blue/far‐red light‐dependent photoreceptor for phototropism in Arabidopsis

In the fern Adiantum capillus-veneris, the phototropic response of the protonemal cells is induced by blue light and partially inhibited by subsequent irradiation with far-red light. This observation strongly suggests the existence of a phytochrome that mediates this blue/far-red reversible response; however, the phytochrome responsible for this response has not been identified. PHY3/NEO1, one of the three phytochrome genes identified in Adiantum, encodes a chimeric photoreceptor composed of both a phytochrome and a phototropin domain. It was demonstrated that phy3 mediates the red light-dependent phototropic response of Adiantum, and that phy3 potentially functions as a phototropin. These findings suggest that phy3 is the phytochrome that mediates the blue/far-red response in Adiantum protonemata. In the present study, we expressed Adiantum phy3 in a phot1 phot2 phototropin-deficient Arabidopsis line, and investigated the ability of phy3 to induce phototropic responses under various light conditions. Blue light irradiation clearly induced a phototropic response in the phy3-expressing transgenic seedlings, and this effect was fully inhibited by simultaneous irradiation with far-red light. In addition, experiments using amino acid-substituted phy3 indicated that FMN-cysteinyl adduct formation in the light, oxygen, voltage (LOV) domain was not necessary for the induction of blue light-dependent phototropism by phy3. We thus demonstrate that phy3 is the phytochrome that mediates the blue/far-red reversible phototropic response in Adiantum. Furthermore, our results imply that phy3 can function as a phototropin, but that it acts principally as a phytochrome that mediates both the red/far-red and blue/far-red light responses.

Variable frequency of plastid RNA editing among ferns and repeated loss of uridine-to-cytidine editing from vascular plants.

The distinct distribution and abundance of C-to-U and U-to-C RNA editing among land plants suggest that these two processes originated and evolve independently, but the paucity of information from several key lineages limits our understanding of their evolution. To examine the evolutionary diversity of RNA editing among ferns, we sequenced the plastid transcriptomes from two early diverging species, Ophioglossum californicum and Psilotum nudum. Using a relaxed automated approach to minimize false negatives combined with manual inspection to eliminate false positives, we identified 297 C-to-U and three U-to-C edit sites in the O. californicum plastid transcriptome but only 27 C-to-U and no U-to-C edit sites in the P. nudum plastid transcriptome. A broader comparison of editing content with the leptosporangiate fern Adiantum capillus-veneris and the hornwort Anthoceros formosae uncovered large variance in the abundance of plastid editing, indicating that the frequency and type of RNA editing is highly labile in ferns. Edit sites that increase protein conservation among species are more abundant and more efficiently edited than silent and non-conservative sites, suggesting that selection maintains functionally important editing. The absence of U-to-C editing from P. nudum plastid transcripts and other vascular plants demonstrates that U-to-C editing loss is a recurrent phenomenon in vascular plant evolution.

Clues to the signals for chloroplast photo-relocation from the lifetimes of accumulation and avoidance responses.

Chloroplast photo-relocation movement is crucial for plant survival; however, the mechanism of this phenomenon is still poorly understood. Especially, the signal that goes from photoreceptor to chloroplast is unknown, although the photoreceptors (phototropin 1 and 2) have been identified and an actin structure (chloroplast actin filaments) has been characterized that is specific for chloroplast movement. Here, in gametophytes of the fern Adiantum capillus-veneris, gametophores of the moss Physcomiterella patens, and leaves of the seed plant Arabidopsis thaliana, we sought to characterize the signaling system by measuring the lifetime of the induced response. Chloroplast movements were induced by microbeam irradiation with high-intensity blue light and recorded. The lifetime of the avoidance state was measured as a lag time between switching off the beam and the loss of avoidance behavior, and that of the accumulation state was measured as the duration of accumulation behavior following the extinction of the beam. The lifetime for the avoidance response state is approximately 3-4 min and that for the accumulation response is 19-28 min. These data suggest that the two responses are based on distinct signals.

Phytosociological Analysis Of Communities With Adiantum Capillusveneris In The Foothills Of The Julian Alps (Western Slovenia)

Abstract We conducted a phytosociological study of the communities hosting the rare and endangered fern Adiantum capillus-veneris in the foothills of the Julian Alps, in Karst and in Istria. Based on a comparison with similar communities elsewhere in the southern Alps (northern Italy) we classified most of the recorded stands into the syntaxa Eucladio-Adiantetum eucladietosum and -cratoneuretosum commutati. Releves from the southern Julian Alps, located in comparatively slightly colder and moister local climate and the dolomite bedrock are classified into the new subassociation -hymenostylietosum recurvirostri subass. nova. Stands with the abundant occurrence of the liverwort Conocephalum conicum, are classified in to the new subassociation -conocephaletosum conici subass. nova. Stands in conglomerate rock shelters along the Soča at Solkan are classified into the new association Phyteumato columnae-Adiantetum ass. nova, a community of transitional character between the classes Adiantetea capilli-veneris and Asplenietea trichomanis.

Isolation and Characterization of a Novel SOMATIC EMBRYOGENESIS RECEPTOR KINASE Gene Expressed in the Fern Adiantum capillus-veneris During Shoot Regeneration In Vitro

SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) genes are expressed primarily in seed plants and are involved in the development of embryos from already-differentiated plant cells. This study provides the first evidence for the existence of a SERK gene, designated AcvSERK1, in a fern, Adiantum capillus-veneris. AcvSERK1 belongs to a small family of receptor-like kinases (RLKs), and its sequence and conserved structure closely resemble SERK homologs in other land plants. Phylogenetic analysis of the SERK gene family showed that AcvSERK1 forms a clade with SERK-like genes from non-seed plants and is a member of the SERK1/2 genes group, involved in somatic embryogenesis. Moreover, our analyses reveal that AcvSERK1 is expressed throughout the entire process of embryo development, but its levels decrease with the formation of shoots and seedlings. Additionally, in situ hybridization showed that AcvSERK1 is expressed during green globular body (GGB)-derived somatic embryogenesis and in meristematic calluses. Our results indicate that the AcvSERK1 gene is a good marker for differentiated cells that are capable of forming embryos in A. capillus-veneris, suggesting that SERK genes have played an important role in embryogenesis during the evolution of land plants.

Phototropin encoded by a single-copy gene mediates chloroplast photorelocation movements in the liverwort Marchantia polymorpha.

Blue-light-induced chloroplast photorelocation movement is observed in most land plants. Chloroplasts move toward weak-light-irradiated areas to efficiently absorb light (the accumulation response) and escape from strong-light-irradiated areas to avoid photodamage (the avoidance response). The plant-specific kinase phototropin (phot) is the blue-light receptor for chloroplast movements. Although the molecular mechanisms for chloroplast photorelocation movement have been analyzed, the overall aspects of signal transduction common to land plants are still unknown. Here, we show that the liverwort Marchantia polymorpha exhibits the accumulation and avoidance responses exclusively induced by blue light as well as specific chloroplast positioning in the dark. Moreover, in silico and Southern-blot analyses revealed that the M. polymorpha genome encodes a single PHOT gene, MpPHOT, and its knockout line displayed none of the chloroplast photorelocation movements, indicating that the sole MpPHOT gene mediates all types of movement. Mpphot was localized on the plasma membrane and exhibited blue-light-dependent autophosphorylation both in vitro and in vivo. Heterologous expression of MpPHOT rescued the defects in chloroplast movement of phot mutants in the fern Adiantum capillus-veneris and the seed plant Arabidopsis (Arabidopsis thaliana). These results indicate that Mpphot possesses evolutionarily conserved regulatory activities for chloroplast photorelocation movement. M. polymorpha offers a simple and versatile platform for analyzing the fundamental processes of phototropin-mediated chloroplast photorelocation movement common to land plants.

Plant nuclear photorelocation movement

Organelle movement and positioning are essential for proper cellular function. A nucleus moves dynamically during cell division and differentiation and in response to environmental changes in animal, fungal, and plant cells. Nuclear movement is well-studied and the mechanisms have been mostly elucidated in animal and fungal cells, but not in plant cells. In prothallial cells of the fern Adiantum capillus-veneris and leaf cells of the flowering plant Arabidopsis thaliana, light induces nuclear movement and nuclei change their position according to wavelength, intensity, and direction of light. This nuclear photorelocation movement shows some common features with the photorelocation movement of chloroplasts, which is one of the best-characterized plant organelle movements. This review summarizes nuclear movement and positioning in plant cells, especially plant-specific nuclear photorelocation movement and discusses the relationship between nuclear photorelocation movement and chloroplast photorelocation movement.

Evaluation of goitrogenic and antithyroidal effect of the fern Adiantum capillus-veneris

Adiantum capillus-veneris L., Pteridaceae, is a fern reputed to have numerous applications in traditional medicine in the treatment of leprosy, animal bites, thyroid dysfunction and musculoskeletal disorder. The proposed study was aimed to investigate the potency of the fern Adiantum capillus-veneris on the thyroid dysfunction - hypothyroidism in terms of determining thyroid gland weight, thyroid peroxidase activity, estimation of iodine in urine, concentrations of total thyroxine (T4), triiodothyronine (T3) and thyroid stimulating hormone (TSH) in serum. The weight of thyroid gland was decreased, while thyroid peroxidase activity, serum T4 (p<0.01) and serum T3 levels (p<0.01) were increased in animals treated with the ethanol plant extract (500mg/kg); but serum TSH level decreased significantly (p<0.01) when compared with hypothyroid control animals. The SOD, Catalase and glutathione antioxidant enzyme levels and lipid peroxidation were measured. The results of lipid peroxidation and antioxidant enzyme assay indicated that the level of malondialdehyde was significantly lowered and the levels of antioxidant enzymes were significantly increased when treated with ethanol extract of Adiantum capillus (500mg/kg). Polyphenolic compounds viz., quercetin and gallic acid were determined by HPTLC analysis. With the outlined results, Adiantum capillus could be used for the regulation of hypothyroidism.

Cold‐induced organelle relocation in the liverwort Marchantia polymorpha L.

Organelles change their subcellular positions in response to various environmental conditions. Recently, we reported that cold treatments alter the intracellular position of chloroplasts and nuclei (cold positioning) in the fern Adiantum capillus-veneris; chloroplasts and nuclei localized to the periclinal cell wall relocated to anticlinal cell wall after cold treatments. To further understand organelle positioning under cold conditions, we studied cold-induced organelle relocation in the liverwort Marchantia polymorpha L. When sporelings and gemmmalings were treated under low temperature (5 °C), chloroplast cold positioning response was successfully induced both in the sporelings and the gemmmalings of M. polymorpha. Using a genetic transformation, nuclei, mitochondria or peroxisomes were visualized with a fluorescent protein, and the transgenic gemmmalings were incubated under the cold condition. Nuclei and peroxisomes, but not mitochondria, clearly relocated from the periclinal cell wall to the anticlinal cell wall after cold treatments. Our findings suggest that several organelles concurrently change their positions in the liverwort cell to cope with cold temperature.

An evolutionarily conserved signaling mechanism mediates far-red light responses in land plants.

Phytochromes are plant photoreceptors important for development and adaptation to the environment. Phytochrome A (PHYA) is essential for the far-red (FR) high-irradiance responses (HIRs), which are of particular ecological relevance as they enable plants to establish under shade conditions. PHYA and HIRs have been considered unique to seed plants because the divergence of seed plants and cryptogams (e.g., ferns and mosses) preceded the evolution of PHYA. Seed plant phytochromes translocate into the nucleus and regulate gene expression. By contrast, there has been little evidence of a nuclear localization and function of cryptogam phytochromes. Here, we identified responses to FR light in cryptogams, which are highly reminiscent of PHYA signaling in seed plants. In the moss Physcomitrella patens and the fern Adiantum capillus-veneris, phytochromes accumulate in the nucleus in response to light. Although P. patens phytochromes evolved independently of PHYA, we have found that one clade of P. patens phytochromes exhibits the molecular properties of PHYA. We suggest that HIR-like responses had evolved in the last common ancestor of modern seed plants and cryptogams and that HIR signaling is more ancient than PHYA. Thus, other phytochromes in seed plants may have lost the capacity to mediate HIRs during evolution, rather than that PHYA acquired it.

The KAC Family of Kinesin-Like Proteins is Essential for the Association of Chloroplasts with the Plasma Membrane in Land Plants

Chloroplasts require association with the plasma membrane for movement in response to light and for appropriate positioning within the cell to capture photosynthetic light efficiently. In Arabidopsis, CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1), KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT 1 (KAC1) and KAC2 are required for both the proper movement of chloroplasts and the association of chloroplasts with the plasma membrane, through the reorganization of short actin filaments located on the periphery of the chloroplasts. Here, we show that KAC and CHUP1 orthologs (AcKAC1, AcCHUP1A and AcCHUP1B, and PpKAC1 and PpKAC2) play important roles in chloroplast positioning in the fern Adiantum capillus-veneris and the moss Physcomitrella patens. The knockdown of AcKAC1 and two AcCHUP1 genes induced the aggregation of chloroplasts around the nucleus. Analyses of A. capillus-veneris mutants containing perinuclear-aggregated chloroplasts confirmed that AcKAC1 is required for chloroplast-plasma membrane association. In addition, P. patens lines in which two KAC genes had been knocked out showed an aggregated chloroplast phenotype similar to that of the fern kac1 mutants. These results indicate that chloroplast positioning and movement are mediated through the activities of KAC and CHUP1 proteins, which are conserved in land plants.

Speed of signal transfer in the chloroplast accumulation response

Chloroplast photorelocation movement is important for plants to perform efficient photosynthesis. Phototropins were identified as blue-light receptors for chloroplast movement in Arabidopsis thaliana and in the fern Adiantum capillus-veneris, whereas neochrome functions as a dual red/blue light receptor in the latter. However, the signal transduction pathways involved in chloroplast movement remain to be clarified. To investigate the kinetic properties of signalling from these photoreceptors to the chloroplasts, we deduced the speed of signal transfer using Adiantum capillus-veneris gametophytes. When a region of dark-adapted gametophyte cells was subjected to microbeam irradiation, chloroplasts moved towards the irradiated area even in subsequent darkness. We therefore recorded the movement and calculated the speeds of signal transfer by time-lapse imaging. Movement speeds under red or blue light were similar, e.g., about 1.0 microm min(-1) in prothallial cells. However, speeds varied according to cell polarity in protonemal cells. The speed of signal transfer from the protonemal apex to the base was approximately 0.7 microm min(-1), but roughly 2.3 microm min(-1) in the opposite direction. The speed of signal transfer in Arabidopsis thaliana mesophyll cells was approximately 0.8 microm min(-1) by comparison. Surprisingly, chloroplasts located farthest away from the microbeam were found to move faster than those in close proximity to the site of irradiation both in Adiantum capillus-veneris and A. thaliana.

Complete chloroplast genome sequence of a tree fern Alsophila spinulosa: insights into evolutionary changes in fern chloroplast genomes

BackgroundFerns have generally been neglected in studies of chloroplast genomics. Before this study, only one polypod and two basal ferns had their complete chloroplast (cp) genome reported. Tree ferns represent an ancient fern lineage that first occurred in the Late Triassic. In recent phylogenetic analyses, tree ferns were shown to be the sister group of polypods, the most diverse group of living ferns. Availability of cp genome sequence from a tree fern will facilitate interpretation of the evolutionary changes of fern cp genomes. Here we have sequenced the complete cp genome of a scaly tree fern Alsophila spinulosa (Cyatheaceae).ResultsThe Alsophila cp genome is 156,661 base pairs (bp) in size, and has a typical quadripartite structure with the large (LSC, 86,308 bp) and small single copy (SSC, 21,623 bp) regions separated by two copies of an inverted repeat (IRs, 24,365 bp each). This genome contains 117 different genes encoding 85 proteins, 4 rRNAs and 28 tRNAs. Pseudogenes of ycf66 and trnT-UGU are also detected in this genome. A unique trnR-UCG gene (derived from trnR-CCG) is found between rbcL and accD. The Alsophila cp genome shares some unusual characteristics with the previously sequenced cp genome of the polypod fern Adiantum capillus-veneris, including the absence of 5 tRNA genes that exist in most other cp genomes. The genome shows a high degree of synteny with that of Adiantum, but differs considerably from two basal ferns (Angiopteris evecta and Psilotum nudum). At one endpoint of an ancient inversion we detected a highly repeated 565-bp-region that is absent from the Adiantum cp genome. An additional minor inversion of the trnD-GUC, which is possibly shared by all ferns, was identified by comparison between the fern and other land plant cp genomes.ConclusionBy comparing four fern cp genome sequences it was confirmed that two major rearrangements distinguish higher leptosporangiate ferns from basal fern lineages. The Alsophila cp genome is very similar to that of the polypod fern Adiantum in terms of gene content, gene order and GC content. However, there exist some striking differences between them: the trnR-UCG gene represents a putative molecular apomorphy of tree ferns; and the repeats observed at one inversion endpoint may be a vestige of some unknown rearrangement(s). This work provided fresh insights into the fern cp genome evolution as well as useful data for future phylogenetic studies.

Low temperature-induced chloroplast relocation mediated by a blue light receptor, phototropin 2, in fern gametophytes

Chloroplast movement in response to light has been known more than 100 years. Chloroplasts move towards weak light and move away from strong light. Dark-induced relocation, called dark positioning, has also been shown. However, the effects of other stimuli on chloroplast movement have not been well characterized. Here we studied low temperature-induced chloroplast relocation (termed cold positioning) in prothallial cells of the gametophytes of the fern Adiantum capillus-veneris. Under weak light chloroplasts in prothallial cells accumulated along the periclinal wall at 25 degrees C, but they moved towards anticlinal walls when the prothalli were subsequently transferred to 4 degrees C. A temperature shift from 25 degrees to 10 degrees C or lower was enough to induce cold positioning, and high-intensity light enhanced the response. Nuclei also relocated from the periclinal position (a position along periclinal walls) to the anticlinal position (a position along anticlinal walls) under cold temperature, whereas mitochondria did not. Cold positioning was not observed in mutant fern gametophytes defective of the blue light photoreceptor, phototropin 2.