RESUMEN
Although polyploidy is pervasive and its evolutionary significance has been recognized, it remains unclear how newly formed polyploid species become established. In particular, the impact of multiple origins on genetic differentiation among populations of a polyploid species and whether lineages of independent origins have different evolutionary potentials remain open questions. We used population genetic and phylogenetic approaches to identify genetic differentiation between lineages with independent origins within an allotetraploid fern, Lepisorus nigripes. A total of 352 individuals from 51 populations were collected throughout the distribution range. To examine the genetic structure, multilocus genotyping, Bayesian population structure analysis, and neighbor-net analysis were carried out using single-copy nuclear genes. Phylogenetic trees were constructed to detect recurrent polyploid origins. Proportions of abortive spores were analysed as the measure of postzygotic reproductive isolation. Two genetically distinct lineages, the East-type and the West-type, were distributed mainly in the eastern and western parts, respectively, of the Japanese archipelago. Phylogenetic analyses indicated independent origins of these types and detected additional independent origins within each type. We also revealed limited genetic recombination between both types, even in their sympatric regions. F1 hybrids between the East- and West-types showed a reduction in fertility. It is likely that the East- and West-types formed independently in the eastern and western parts of Japan, respectively. The limited genetic recombination and reduced fertility of hybrids suggest that the two types are at an incipient stage of speciation. Two polyploid lineages with independent geographic origins could develop reproductive isolation barrier(s).
Asunto(s)
Polypodiaceae/genética , Polypodiaceae/fisiología , Teorema de Bayes , Evolución Molecular , Filogenia , Poliploidía , Polypodiaceae/clasificación , Reproducción/genética , Reproducción/fisiología , Aislamiento ReproductivoRESUMEN
Microsorum pteropus has been proven to be a potential novel aquatic Cd hyperaccumulator. In this study, Non-invasive Micro-test Technology (NMT) was used to observe the ion fluxes of different M. pteropus tissues under Cd exposure. M. pteropus can hyperaccumulate more than 1000 mg/kg Cd in roots and leaves and approximately 600 mg/kg Cd in stems after seven days of exposure to 500 µM Cd, showing that this plant have a great capacity for Cd enrichment and resistance. The NMT test found H+ fluxes increased in all tissues after Cd exposure, with the largest increases being observed in stems, followed by the leaves and roots. Cd2+ fluxes showed different accumulation levels in different tissues, with low-level Cd exposure leading to influxes into roots and leaves, and high-level Cd exposure resulting in effluxes from roots. No significant influxes or effluxes were observed in leaves under high-level Cd exposure, or in stems under low- and high-levels of Cd exposure. However, transient high-level Cd exposure showed long-term Cd2+ influxes into roots and short-term Cd2+ effluxes out of stems and leaves. The roots of M. pteropus had greater regulation mechanisms for Cd enrichment and resistance, with influxes occurring following low-level exposure and effluxes occurring from high-level exposure. When exposed to Cd, M. pteropus stems showed less transportation and absorption. Low-level Cd exposure resulted in individual leaves directly absorbing Cd from hydroponic solutions. Different Cd enrichment and resistance mechanisms were exhibited by different M. pteropus tissues.
Asunto(s)
Cadmio/toxicidad , Polypodiaceae/fisiología , Contaminantes del Suelo/toxicidad , Animales , Transporte Biológico , Quirópteros , Hidroponía , Hojas de la Planta/fisiología , Raíces de PlantasRESUMEN
To better monitor and remediate environments contaminated by cadmium (Cd), plants are used as hyperaccumulators or biomonitors; however, few have been identified for aquatic Cd pollution. In our study, two aquatic ornamental plants, Microsorum pteropus (Blume) Copel. and Echinodorus grisebachii Small, were studied for their Cd accumulation capacity, morphological characteristics, and leaf physiological indexes. Microsorum pteropus (Blume) Copel. leaf has the potential to hyperaccumulate Cd (166 mg/kg dry weight for 1 mg/L exposure), with no significant physiological difference under exposure. Echinodorus grisebachii Small had sensitive diagnostic responses to Cd toxicity, such as significant decreases in Chl (a + b) and Chl-a/b, increased peroxidase (POD) activity, greater malondialdehyde (MDA) content, and increased soluble sugar content. These results suggest that Microsorum pteropus (Blume) Copel. could have the potential to be a Cd hyperaccumulator, while Echinodorus grisebachii Small could serve as a biomonitor for Cd-contaminated water bodies.
Asunto(s)
Alismataceae/metabolismo , Cadmio/metabolismo , Polypodiaceae/metabolismo , Contaminantes del Suelo/metabolismo , Alismataceae/anatomía & histología , Alismataceae/fisiología , Biodegradación Ambiental , Hojas de la Planta/fisiología , Polypodiaceae/anatomía & histología , Polypodiaceae/fisiologíaRESUMEN
Microsorum pteropus (M. pteropus), an aquatic Polypodiaceae fern, was identified as a novel potential cadmium (Cd) hyperaccumulator in our previous study. This study reveals the Cd-resistance mechanisms and their difference between the root and leaf of M. pteropus based on analyses of photosynthesis, antioxidant systems and gene expression. A high level of Cd at 500µM was used to treat the samples to test the effects of this compound. Superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA) and flavonoids were used as indicators for antioxidant system changes. Five chlorophyll fluorescent parameters including the maximal photochemical efficiency of photosystem II (Fv/Fm), effective quantum yield of photosystem II (Y(II)), photochemical quenching (qP), nonphotochemical quenching (qN) and electron transport rate (ETR) were measured to determine the photosynthetic changes. RNA-sequencing analysis was used to study the changes in gene expression. The results showed that after exposure to high levels of Cd, the concentrations of enzymatic oxidants (SOD and POD) were significantly increased, while the MDA levels were significantly decreased. There were no significant changes for the chlorophyll fluorescent parameters during Cd stress, which indicates that M. pteropus is highly effective at protecting itself. Certain functional genes, including photosystem genes and secondary metabolites, had significantly altered levels of expression. Different Cd-resistance mechanisms were found between the root and leaf tissues of M. pteropus. The root tissues of M. pteropus resist Cd damage using antioxidants, while its leaf tissues mainly protect themselves using photosystem self-protection.
Asunto(s)
Cadmio/metabolismo , Hojas de la Planta/fisiología , Raíces de Plantas/fisiología , Polypodiaceae/fisiología , Antioxidantes/fisiología , Clorofila , Regulación de la Expresión Génica de las Plantas , FotosíntesisRESUMEN
In-vitro studies of the ontogeny and mating system of the gametophytes of Lepisorus nudus were carried out through multispore and isolate cultures lasting 23 weeks. Spore germination begins early, on day 5-6. Spore germination pattern was Vittaria type and the germination percentage reached 82.69% (± 3.20%). Filamentous gametophyte did not branch and never produce separate prothalli. Occasionally the branching and separate prothalli were produced from mature and cordate gametophytes. Prothallial development was Drynaria type (cordate gametophytes with notched apex) contrary to other known species of Lepisorus, where gametophyte development was Kaulinia type (strap gametophytes without apical notch). Gametophyte production in multispore cultures reached up-to 75.6% (± 18.85%). All isolates initially produced archegonia and antheridia only after a prolonged cessation of production in archegonia. In contrast, only 37.2% (±12.63%) of individuals in multispore culture exhibited the same pattern with 29.8% (±7.56%) developing as males that did not produce archegonia by the end of the study. Only 37.2% (±12.63%) of archegoniate gametophytes developed antheridia by the end of the study and only once archegonia had degenerated; i.e., a temporal gap existed in expression of female and male gametangia. In multispore culture, only 26.21% (±5.70%) sporophytes developed on 160th day by fusion of female and male gametes that were derived from matings between sib gametophytes. In contrast, isolated gametophytes did not produce sporophytes. In isolate gametophytes, mature archegonia could not take delivery of male gametangia because antheridia were produced sequentially. This study suggests that the sequential expression of gametangia and absence of the intragametophytic selfing may also be a possible cause of reproductive barriers. Lepisorus nudus promotes inter-gametophytic selfing as an adaptive mechanism for reproductive success in multispore culture. This study presents a detailed account on reproductive biology of the taxa whose population is decreasing at distressing rate.
Asunto(s)
Germinación , Polypodiaceae/fisiología , Esporas/fisiología , Células Germinativas de las Plantas/crecimiento & desarrollo , Células Germinativas de las Plantas/fisiología , Polypodiaceae/crecimiento & desarrollo , ReproducciónRESUMEN
Fern spore is a good single-cell model for studying the sophisticated molecular networks in asymmetric cell division, differentiation, and polar growth. Osmunda cinnamomea L. var. asiatica is one of the oldest fern species with typical separate-growing trophophyll and sporophyll. The chlorophyllous spores generated from sporophyll can germinate without dormancy. In this study, the spore ultrastructure, antioxidant enzyme activities, as well as protein and gene expression patterns were analyzed in the course of spore germination at five typical stages (i.e. mature spores, rehydrated spores, double-celled spores, germinated spores, and spores with protonemal cells). Proteomic analysis revealed 113 differentially expressed proteins, which were mainly involved in photosynthesis, reserve mobilization, energy supplying, protein synthesis and turnover, reactive oxygen species scavenging, signaling, and cell structure modulation. The presence of multiple proteoforms of 25 differentially expressed proteins implies that post-translational modification may play important roles in spore germination. The dynamic patterns of proteins and their encoding genes exhibited specific characteristics in the processes of cell division and rhizoid tip growth, which include heterotrophic and autotrophic metabolisms, de novo protein synthesis and active protein turnover, reactive oxygen species and hormone (brassinosteroid and ethylene) signaling, and vesicle trafficking and cytoskeleton dynamic. In addition, the function skew of proteins in fern spores highlights the unique and common mechanisms when compared with evolutionarily divergent spermatophyte pollen. These findings provide an improved understanding of the typical single-celled asymmetric division and polar growth during fern spore germination.
Asunto(s)
Germinación , Proteínas de Plantas/metabolismo , Polypodiaceae/crecimiento & desarrollo , Polypodiaceae/ultraestructura , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Polypodiaceae/fisiología , Proteómica/métodos , Análisis de la Célula Individual , Esporas/crecimiento & desarrollo , Esporas/ultraestructuraRESUMEN
Volatile organic compounds (VOCs) are common among plants, both as attractants for pollinators and as defence against herbivores. While much studied among flowering plants, the prevalence and function of VOCs among ferns is little known. Using headspace sorption and gas chromatography, we analysed the VOCs of dried specimens of six species of grammitid fern (Polypodiaceae), including two species of the genus Melpomene, which is characterised by a distinctive sweet smell. We identified 38 VOCs, including 22 not previously recorded among ferns. The two species of Melpomene had distinct VOC cocktails, including 12 substances not found in the other four studied genera, mainly involving fatty acid derivatives (FADs) and aromatics. We propose that these VOCs have, at least in part, a function in herbivore defence, but note that the VOC bouquet of Melpomene is distinct from that typically found in angiosperms.
Asunto(s)
Polypodiaceae/química , Compuestos Orgánicos Volátiles/análisis , Helechos/química , Cromatografía de Gases y Espectrometría de Masas , Herbivoria , Odorantes/análisis , Polypodiaceae/fisiología , Compuestos Orgánicos Volátiles/químicaRESUMEN
The epiphytic fern Microgramma squamulosa occurs in the Neotropics and shows dimorphic sterile and fertile leaves. The present study aimed to describe and compare qualitatively and quantitatively macroscopic and microscopic structural characteristics of the dimorphic leaves of M. squamulosa, to point more precisely those characteristics which may contribute to epiphytic adaptations. In June 2009, six isolated host trees covered by M squamulosa were selected close to the edge of a semi-deciduous seasonal forest fragment in the municipality of Novo Hamburgo, State of Rio Grande do Sul, Brazil. Macroscopic and microscopic analyzes were performed from 192 samples for each leaf type, and permanent and semi-permanent slides were prepared. Sections were observed under light microscopy using image capture software to produce illustrations and scales, as well as to perform quantitative analyses. Fertile and sterile leaves had no qualitative structural differences, being hypostomatous and presenting uniseriate epidermis, homogeneous chlorenchyma, amphicribal vascular bundle, and hypodermis. The presence of hypodermal tissue and the occurrence of stomata at the abaxial face are typical characteristics ofxeromorphic leaves. Sterile leaves showed significantly larger areas (14.80cm2), higher sclerophylly index (0.13g/cm2) and higher stomatal density (27.75stomata/mm2) than fertile leaves. The higher sclerophylly index and the higher stomatal density observed in sterile leaves are features that make these leaves more xeromorphic, enhancing their efficiency to deal with limited water availability in the epiphytic environment, compared to fertile leaves.
Asunto(s)
Adaptación Fisiológica/fisiología , Hojas de la Planta/fisiología , Polypodiaceae/fisiología , Hojas de la Planta/anatomía & histología , Hojas de la Planta/citología , Polypodiaceae/anatomía & histología , Polypodiaceae/citologíaRESUMEN
Positive species interactions (facilitation) play an important role in shaping the structures and species diversity of ecological communities, particularly under stressful environmental conditions. Epiphytes in rainforests often grow in multiple-species clumps, suggesting interspecies facilitation. However, little is known about the patterns and mechanisms of epiphyte co-occurrence. We assessed the interactions of two widespread epiphyte species, Asplenium antiquum and Haplopteris zosterifolia, by examining their co-occurrence and size-class association in the field. To elucidate factors controlling their interactions, we conducted reciprocal-removal and greenhouse-drought experiments, and nutrient and isotope analyses. Forty-five percent of H. zosterifolia co-occurred with A. antiquum, whereas only 17% of A. antiquum co-occurred with H. zosterifolia. Removing the fronds plus substrate of A. antiquum reduced the relative frond length and specific leaf area of H. zosterifolia, but removing fronds only had little effect. Removing H. zosterifolia had no significant effects on the growth of A. antiquum. H. zosterifolia co-occurring and not co-occurring with A. antiquum had similar foliar nutrient concentrations and δ(15)N values, suggesting that A. antiquum does not affect the nutrient status of H. zosterifolia. Reduced growth of H. zosterifolia with the removal of A. antiquum substrate, together with higher foliar δ(13)C for H. zosterifolia growing alone than those co-occurring with A. antiquum, suggest that A. antiquum enhances water availability to H. zosterifolia. This enhancement probably resulted from water storage in the substrate of A. antiquum, which could hold water up to 6.2 times its dry weight, and from reduced evapotranspiration due to shading of A. antiquum fronds. Greater water loss occurred in the frond-clipped group than the unclipped group between days 3-13 of the drought treatment. Our results imply that drought mitigation by substrate-forming epiphytes is important for maintaining epiphyte diversity in tropic and subtropic regions with episodic water limitations, especially in the context of anthropogenic climate change.
Asunto(s)
Sequías , Hojas de la Planta/fisiología , Polypodiaceae/fisiología , Agua/metabolismo , Isótopos de Carbono , Ecosistema , Transpiración de Plantas/fisiología , Clima TropicalRESUMEN
The epiphytic fern Microgramma squamulosa occurs in the Neotropics and shows dimorphic sterile and fertile leaves. The present study aimed to describe and compare qualitatively and quantitatively macroscopic and microscopic structural characteristics of the dimorphic leaves of M. squamulosa, to point more precisely those characteristics which may contribute to epiphytic adaptations. In June 2009, six isolated host trees covered by M. squamulosa were selected close to the edge of a semi-deciduous seasonal forest fragment in the municipality of Novo Hamburgo, State of Rio Grande do Sul, Brazil. Macroscopic and microscopic analyzes were performed from 192 samples for each leaf type, and permanent and semi-permanent slides were prepared. Sections were observed under light microscopy using image capture software to produce illustrations and scales, as well as to perform quantitative analyses. Fertile and sterile leaves had no qualitative structural differences, being hypostomatous and presenting uniseriate epidermis, homogeneous chlorenchyma, amphicribal vascular bundle, and hypodermis. The presence of hypodermal tissue and the occurrence of stomata at the abaxial face are typical characteristics of xeromorphic leaves. Sterile leaves showed significantly larger areas (14.80cm²), higher sclerophylly index (0.13g/cm²) and higher stomatal density (27.75stomata/mm²) than fertile leaves. The higher sclerophylly index and the higher stomatal density observed in sterile leaves are features that make these leaves more xeromorphic, enhancing their efficiency to deal with limited water availability in the epiphytic environment, compared to fertile leaves.
El helecho epífito Microgramma squamulosa se encuentra en el Neotrópico y tiene hojas estériles y fértiles dimorfas. El objetivo de este estudio fue describir y comparar cuantitativa y cualitativamente la organización estructural de las hojas de la M. squamulosa, investigando las características morfológicas y anatómicas, y señalando los factores que contribuyen a la adaptación al ambiente epífito. Los análisis macroscópicos y microscópicos se realizaron a partir de 192 muestras de hojas de cada tipo. Láminas permanentes y semi-permanentes fueron preparadas y las secciones fueron observadas en el microscopio de luz. Hojas fértiles y estériles no mostraron diferencias estructurales cualitativas, son hipostomáticas, presentan epidermis uniseriada, haz vascular anficrival e hipodermis. La presencia de hipodermis y aparatos estomáticos en la nsuperficie abaxial de la epidermis son típicas de hojas xeromórficas. Hojas estériles presentaran áreas significativamente mayores, tasa más alta de esclerofilia y mayor densidad de estomas que hojas fértiles. La mayor tasa de esclerofilia y mayor densidad de estomas son características que hacen las hojas estériles más xeromórficas, aumentando su eficiencia para hacer frente a la disponibilidad de agua limitada en el ambiente epífito, en comparación con las hojas fértiles.
Asunto(s)
Adaptación Fisiológica/fisiología , Hojas de la Planta/fisiología , Polypodiaceae/fisiología , Hojas de la Planta/anatomía & histología , Hojas de la Planta/citología , Polypodiaceae/anatomía & histología , Polypodiaceae/citologíaRESUMEN
Cyclic electron flow (CEF) plays an important role in photoprotection for angiosperms under environmental stresses. However, ferns are more sensitive to drought and their water transport systems are not as efficient as those of angiosperms, it is unclear whether CEF also contributes to photoprotection in these plants. Using Microsorum punctatum and Paraleptochillus decurrens, we studied the electron fluxes through both photosystem I (PSI) and photosystem II (PSII) under water stress and their leaf anatomies. Our goal was to determine if CEF functions in the photoprotection of these ferns and, if so, whether CEF stimulation is related to leaf anatomy. Compared with P. decurrens, M. punctatum had thicker leaves and cuticles and higher water storage capacity, but lower stomatal density and slower rate of water loss. During induced drought, the decrease in leaf water potential (Ψ(leaf) ) was more pronounced in P. decurrens than in M. punctatum. For both species, the decline in Ψ(leaf) was associated with a lower effective PSII quantum yield, photochemical quantum yield of PSI and electron transport rate (ETR), whereas increases were found in the quantum yield of regulated energy dissipation, CEF and CEF/ETR(II) ratio. Values for CEF and the CEF/ETR(II) ratio peaked in M. punctatum at a light intensity of 500-600 µmol m(-2) s(-1) vs only 150-200 µmol m(-2) s(-1) in P. decurrens. Therefore, our results indicate that the stimulation of CEF in tropical ferns contributes to their photoprotection under water stress, and is related to their respective drought tolerance and leaf anatomy.
Asunto(s)
Polypodiaceae/fisiología , Estrés Fisiológico/fisiología , Agua/metabolismo , Transporte Biológico , Clorofila/metabolismo , Deshidratación , Sequías , Transporte de Electrón , Luz , Fotosíntesis/fisiología , Complejo de Proteína del Fotosistema I/fisiología , Complejo de Proteína del Fotosistema II/fisiología , Epidermis de la Planta/anatomía & histología , Epidermis de la Planta/metabolismo , Epidermis de la Planta/fisiología , Epidermis de la Planta/efectos de la radiación , Hojas de la Planta/anatomía & histología , Hojas de la Planta/metabolismo , Hojas de la Planta/fisiología , Hojas de la Planta/efectos de la radiación , Estomas de Plantas/anatomía & histología , Estomas de Plantas/metabolismo , Estomas de Plantas/fisiología , Estomas de Plantas/efectos de la radiación , Transpiración de Plantas/fisiología , Polypodiaceae/anatomía & histología , Polypodiaceae/metabolismo , Polypodiaceae/efectos de la radiación , Especificidad de la EspecieRESUMEN
OBJECTIVE: To have a better utilization of diurnal photosynthetic variation of Drynaria fortunei in three light environments and provide theoretical basis for its artificial cultivation. METHODS: Diurnal photosynthetic variation of Drynaria fortunei were determinated by portable photosynthesis analysis system (Li-6400), and correlation between physiological and environmental factors was further analysed. RESULTS: The diurnal net photosynthetic rate (NPR) exhibited a single peak curve, with the peak value of NPR occurring at 15:30. The mean diurnal Pn of D. fortunei in three environments followed a tread of tree epiphytes > shine > shade. WUE had significantly positive correlation with NPR. Air temperature (Ta), ambient CO2 concentration (Ca) and relative humidity (RH) were the main environmental factors for NPR of D. fortunei. CONCLUSION: The optimum cultivation condition of D. fortunei is 32 degrees C, RH around 40%, and appropriate shade is recommended.