Fern Adiantum Research Articles

Chloroplast-actin filaments decide the direction of chloroplast avoidance movement under strong light in Arabidopsis thaliana.

Chloroplast-actin (cp-actin) filaments are crucial for light-induced chloroplast movement, and appear in the front region of moving chloroplasts when visualized using GFP-mouse Talin. They are short and thick, exist between a chloroplast and the plasma membrane, and move actively and rapidly compared to cytoplasmic long actin filaments that run through a cell. The average period during which a cp-actin filament was observed at the same position was less than 0.5s. The average lengths of the cp-actin filaments calculated from those at the front region of the moving chloroplast and those around the chloroplast periphery after stopping the movement were almost the same, approximately 0.8µm. Each cp-actin filament is shown as a dotted line consisting of 4-5 dots. The vector sum of cp-actin filaments in a moving chloroplast is parallel to the moving direction of the chloroplast, suggesting that the direction of chloroplast movement is regulated by the vector sum of cp-actin filaments. However, once the chloroplasts stopped moving, the vector sum of the cp-actin filaments around the chloroplast periphery was close to zero, indicating that the direction of movement was undecided. To determine the precise structure of cp-actin filaments under electron microscopy, Arabidopsis leaves and fern Adiantum capillus-veneris gametophytes were frozen using a high-pressure freezer, and observed under electron microscopy. However, no bundled microfilaments were found, suggesting that the cp-actin filaments were unstable even under high-pressure freezing.

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 considered 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.

Phytochemical Screening, GC-MS Analysis of Methanolic Extract of the Fern Adiantum Caudatum from Southern Western Ghats

The present study was to screen the presence of phytochemicals in the methanol extract of fern Adiantum caudatum species by composed with qualitative and quantitative screening methods. In qualitative analysis, the presence of pharmacologically active phytochemicals such as alkaloids, flavonoids, glycosides, steroids, tannins, terpenoids, saponins, phenols, volatile oils and resins were screened. GC-MS chromatogram analysis of the methanolic extract of Adiantum caudatum showed 12 peaks corresponding to 12 different compounds. The percentage of major bioactive compounds were 2-Hydroxymethyl-9-[Beta.-D-Ribofuranosyl] Hypoxanthine (17.995%), 2-Undecene,5-methyl- (33.497%), Pentadecane,2,6,10,14-Tetramethyl- (14.977%), Nonadecane (7.588%), Dodecane, 2,6,10-trimethyl- (1.421%), 3,7,11,15-Tetramethyl-2-Hexadecen-1-ol (2.825%), Nonadecane (7.855%). The identification of bioactive compounds is based on the retention time, peak area, molecular formula, and probability.

Metabolic and Oxidative Changes in the Fern Adiantum raddianum upon Foliar Application of Metals

Cadmium (Cd) or nickel (Ni) were applied as a foliar spray (1 µM solution over one month) to mimic air pollution and to monitor metabolic responses and oxidative stress in the pteridophyte species. Exogenous metals did not affect the metal content of the soil and had relatively little effect on the essential elements in leaves or rhizomes. The amounts of Cd and Ni were similar in treated leaves (7.2 µg Cd or 5.3 µg Ni/g DW in mature leaves compared with 0.4 µg Cd or 1.2 µg Ni/g DW in the respective control leaves), but Ni was more abundant in rhizomes (56.6 µg Ni or 3.4 µg Cd/g DW), resulting in a higher Cd translocation and bioaccumulation factor. The theoretical calculation revealed that ca. 4% of Cd and 5.5% of Ni from the applied solution per plant/pot was absorbed. Excess Cd induced stronger ROS production followed by changes in SOD and CAT activities, whereas nitric oxide (NO) stimulation was less intense, as detected by confocal microscopy. The hadrocentric vascular bundles in the petioles also showed higher ROS and NO signals under metal excess. This may be a sign of increased ROS formation, and high correlations were observed. Proteins and amino acids were stimulated by Cd or Ni application in individual organs, whereas phenols and flavonols were almost unaffected. The data suggest that even low levels of exogenous metals induce an oxidative imbalance, although no visible damage is observed, and that the responses of ferns to metals are similar to those of seed plants or algae.

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

Morphological and anatomical adaptations to dry, shady environments in Adiantum reniforme var. sinense (Pteridaceae).

The natural distribution of the rare perennial fern Adiantum reniforme var. sinense (Pteridaceae), which is endemic to shady cliff environments, is limited to small areas of Wanzhou County, Chongqing, China. In this study, we used brightfield and epifluorescence microscopy to investigate the anatomical structures and histochemical features that may allow this species to thrive in shady, dry cliff environments. The A. reniforme var. sinense sporophyte had a primary structure and a dictyostele. The plants of this species had an endodermis, sclerenchyma layers and hypodermal sterome, reflecting an adaption to dry cliff environments. Blades had a thin cuticle and isolateral mesophyll, suggesting a tolerance of shady environments. These characteristics are similar to many sciophyte ferns such as Lygodium japonicum and Pteris multifida. Thus, the morphological and anatomical characteristics of A. reniforme var. sinense identified in this study are consistent with adaptations to shady, dry cliff environments.

Thidiazuron outpaces 6-benzylamino purine and kinetin in delaying flower senescence in Gladiolus grandiflora by alleviating physiological and biochemical responses

Studies on the mechanism of desiccation tolerance in the resurrection fern Adiantum raddianumTumkur Govindaraju Banupriya, Chandraiah Ramyashree, Devaraja Akash, Neeragunda Shivaraj Yathish, Ramasandra Govindarao Sharthchandra

Antibacterial potential of Antimicrobial peptides containing whole proteins of two Adiantum species from Himalaya against selected human bacterial pathogens

Increasing tendency of drug resistance and continuously emerging new diseases have limited the available therapeutic options. Plants are still a positive hope for search of new therapeutic agents, which have provided many effective therapeutic agents and have not been yet explored to their full potential. In the present study, two ferns Adiantum edgeworthii and Adiantum capilllus-veneris from the Himalayas, have been explored for the presence of antimicrobial peptides (AMPs) in them. Antimicrobial peptides are different class of therapeutic agents having multimodal action mechanism and different site of action. Hence they could be a solution against the problem of drug resistance. In the present study, whole proteins (WPs) of the ferns were precipitated using TCA, and low molecular weight protein fractions (LMPFs) of WPs were isolated using SDS-PAGE. Antibacterial activities of WPs and LMPFs were tested against six human pathogenic bacteria S. aureus, S. pneumoniae, E. faecalis, and K. pneumoniae, P. aeruginosa and E. coli. The results showed that AMPs were present both the ferns and antibacterial potency of LMPFs was higher than WPs. It was also observed that WPs of A. capillus-veneris was about 11.4% more active than WPs of A. edgeworthii. Antibacterial activity of WPs was compared with two standard antibiotics (Amoxicillin and Erythromycin) and comparable results were obtained. Further research for purification and characterization of pure antimicrobial peptides from these plants are expected to provide new therapeutic agents.

Studies on the mechanism of desiccation tolerance in the resurrection fern Adiantum raddianum

Studies on the mechanism of desiccation tolerance in the resurrection fern Adiantum raddianum

Impacts of invasive earthworms and deer on native ferns in forests of northeastern North America

Forest understory plants in eastern North America experience heavy white-tailed deer browse and impacts associated with invasive species, including of non-native earthworms. Deer and earthworms are well-recognized ecosystem engineers due to their ability to alter understory plant dynamics. We examined interactive effects of earthworms and deer on four woodland ferns (Adiantum pedatum, Polystichum acrostichoides, Dryopteris marginalis, and Dennstaedtia punctilobula) using field and common garden experiments. In the field we planted ferns into fenced and deer-accessible plots in areas with and without earthworms. In a common garden, we assessed both fern responses to different earthworms and fern effects on earthworm survival and biomass. Venue was important in determining experimental outcomes. In the field, A. pedatum and P. acrostichoides showed higher survival and P. acrostichoides grew taller or produced more fronds in worm-invaded areas. Deer presence/absence was not a significant explanatory variable. In the common garden, earthworms had no discernible effect on ferns, but fern species identity varied in its effect on earthworm survival and leaf litter decomposition. Our findings indicate that, contrary to many other understory species, common ferns benefit or are unaffected by earthworms. That we obtained different and even contradictory results in different venues should encourage investigators to validate common garden findings in the field.

Comparative transcriptome analysis of two reproductive modes in Adiantum reniforme var. sinense targeted to explore possible mechanism of apogamy

BackgroundApogamy is a unique asexual reproduction in the ferns, in which somatic cells of gametophytes go through dedifferentiation and then differentiate into haploid sporophytes bypassing fertilization. Restricted to the lack of genomic information, molecular mechanisms of apogamy have remained unclear. Comparative transcriptome analysis was conducted at six stages between sexual reproduction and apogamy in the fern Adiantum reniforme var. sinense, in an effort to identify genes and pathways that might initiate the asexual reproduction.ResultsApproximately 928 million high-quality clean reads were assembled into 264,791 unigenes with an average length of 615 bp. A total of 147,865 (55.84%) unigenes were successfully annotated. Differential genes expression analysis indicated that transcriptional regulation was more active in the early stage of apogamy compared to sexual reproduction. Further comparative analysis of the enriched pathways between the early stages of the two reproductive modes demonstrated that starch and sucrose metabolism pathway responsible for cell wall was only significantly enriched in asexual embryonic cell initiation. Furthermore, regulation of plant hormone related genes was more vigorous in apogamy initiation.ConclusionThese findings would be useful for revealing the initiation of apogamy and further understanding of the mechanisms related to asexual reproduction.

Two molecular species of phytochrome A with distinct modes of action.

Adaptation of plants to environmental light conditions is achieved via operation of a highly complex photoreceptor apparatus. It includes the phytochrome system comprising phytochromes A and B (phyA and phyB) as the major components. phyA differs from phyB by several properties, including its ability to mediate all three photoresponse modes - the very low and low fluence responses (VLFR and LFR respectively) and the high irradiance responses (HIR), whereas phyB is responsible for LFR. This review discusses the uniqueness of phyA in terms of its structural and functional heterogeneity. The photoreceptor is presented in monocots and dicots by two native molecular species, phyA' and phyA'', differing by spectroscopic, photochemical and phenomenological properties. phyA differentiation into substates includes post-translational phosphorylation of a serine residue(s) at the N-terminal extension of the molecule with phyA' being the phosphorylated species and phyA'', dephosphorylated. They differ also by their mode of action, which depends on the cellular context. The current working hypothesis is that phyA' mediates VLFR and phyA'', HIR and LFR. The content and functional activity of the two pools are regulated by light and by phosphatase/kinase equilibrium and pH in darkness, what contributes to the fine-tuning of the phytochrome system. Detection of the native pools of the cryptogamic plant fern Adiantum capillus-veneris phy1 (phy1' and phy1'') similar to those of phyA suggests that the structural and functional heterogeneity of phyA is not a unique phenomenon and may have arisen earlier in the molecular evolution of the phytochrome system than the appearance of the angiosperm phytochromes.

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 novel chloroplast gene reported for flagellate plants

Gene space in plant plastid genomes is well characterized and annotated, yet we discovered an unrecognized open reading frame (ORF) in the fern lineage that is conserved across flagellate plants. We initially detected a putative uncharacterized ORF by the existence of a highly conserved region between rps16 and matK in a series of matK alignments of leptosporangiate ferns. We mined available plastid genomes for this ORF, which we now refer to as ycf94, to infer evolutionary selection pressures and assist in functional prediction. To further examine the transcription of ycf94, we assembled the plastid genome and sequenced the transcriptome of the leptosporangiate fern Adiantum shastense Huiet & A.R. Sm. The ycf94 predicted protein has a distinct transmembrane domain but with no sequence homology to other proteins with known function. The nonsynonymous/synonymous substitution rate ratio of ycf94 is on par with other fern plastid protein-encoding genes, and additional homologs can be found in a few lycophyte, moss, hornwort, and liverwort plastid genomes. Homologs of ycf94 were not found in seed plants. In addition, we report a high level of RNA editing for ycf94 transcripts-a hallmark of protein-coding genes in fern plastomes. The degree of sequence conservation, together with the presence of a distinct transmembrane domain and RNA-editing sites, suggests that ycf94 is a protein-coding gene of functional significance in ferns and, potentially, bryophytes and lycophytes. However, the origin and exact function of this gene require further investigation.

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.

Sporangium Exposure and Spore Release in the Peruvian Maidenhair Fern (Adiantum peruvianum, Pteridaceae).

We investigated the different processes involved in spore liberation in the polypod fern Adiantum peruvianum (Pteridaceae). Sporangia are being produced on the undersides of so-called false indusia, which are situated at the abaxial surface of the pinnule margins, and become exposed by a desiccation-induced movement of these pinnule flaps. The complex folding kinematics and functional morphology of false indusia are being described, and we discuss scenarios of movement initiation and passive hydraulic actuation of these structures. High-speed cinematography allowed for analyses of fast sporangium motion and for tracking ejected spores. Separation and liberation of spores from the sporangia are induced by relaxation of the annulus (the ‘throwing arm’ of the sporangium catapult) and conservation of momentum generated during this process, which leads to sporangium bouncing. The ultra-lightweight spores travel through air with a maximum velocity of ~5 m s-1, and a launch acceleration of ~6300g is measured. In some cases, the whole sporangium, or parts of it, together with contained spores break away from the false indusium and are shed as a whole. Also, spores can stick together and form spore clumps. Both findings are discussed in the context of wind dispersal.

The evolutionary conservation of rps3 introns and rps19-rps3-rpl16 gene cluster in Adiantum capillus-veneris mitochondria.

Ferns are a large and evolutionarily critical group of vascular land plants for which quite limited mitochondrial gene content and genome organization data are, currently, available. This study reports that the gene for the ribosomal protein S3 (rps3) is preserved and physically clustered to an upstream rps19 and a downstream overlapping rpl16 locus in the mitochondrial DNA of the true fern Adiantum capillus-veneris L. Sequence analysis also revealed that the rps3 gene is interrupted by two cis-splicing group II introns, like the counterpart in lycopod and gymnosperm representatives. A preliminary polymerase chain reaction (PCR) survey confirmed a scattered distribution pattern of both the rps3 introns also in other fern lineages. Northern blot and reverse transcription (RT)-PCR analyses demonstrated that the three ribosomal protein genes are co-transcribed as a polycistronic mRNA and modified by RNA editing. Particularly, the U-to-C type editing amends numerous genomic stop codons in the A. capillus-veneris rps19, rps3 and rpl16 sequences, thus, assuring the synthesis of complete and functional polypeptides. Collectively, the findings from this study further expand our knowledge of the mitochondrial rps3 architecture and evolution, also, bridging the significant molecular data gaps across the so far underrepresented ferns and all land plants.

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.