RESUMEN
Salt secretion is an important strategy used by the mangrove plant Aegiceras corniculatum to adapt to the coastal intertidal environment. However, the structural, developmental and functional analyses on the leaf salt glands, particularly the salt secretion mechanism, are not well documented. In this study, we investigated the structural, developmental and degenerative characteristics and the salt secretion mechanisms of salt glands to further elucidate the mechanisms of salt tolerance of A. corniculatum. The results showed that the salt gland cells have a large number of mitochondria and vesicles, and plenty of plasmodesmata as well, while chloroplasts were found in the collecting cells. The salt glands developed early and began to differentiate at the leaf primordium stage. We observed and defined three stages of salt gland degradation for the first time in A. corniculatum, where the secretory cells gradually twisted and wrinkled inward and collapsed downward as the salt gland degeneration increased and the intensity of salt gland autofluorescence gradually diminished. In addition, we found that the salt secretion rate of the salt glands increased when the treated concentration of NaCl increased, reaching the maximum at 400 mM NaCl. The salt-secreting capacity of the salt glands of the adaxial epidermis is significantly greater than that of the abaxial epidermis. The real-time quantitative PCR results indicate that SAD2, TTG1, GL2 and RBR1 may be involved in regulating the development of the salt glands of A. corniculatum. Moreover, Na+/H+ antiporter, H+-ATPase, K+ channel and Cl- channel may play important roles in the salt secretion of salt glands. In sum mary, this study strengthens the understanding of the structural, developmental and degenerative patterns of salt glands and salt secretion mechanisms in mangrove recretohalophyte A. corniculatum, providing an important reference for further studies at the molecular level.
Asunto(s)
Primulaceae , Glándula de Sal , Ambiente , Hojas de la Planta/metabolismo , Primulaceae/fisiología , Cloruro de Sodio/metabolismoRESUMEN
The changes in plant life behaviors and water status are accompanied by electrophysiological activities. In this study, the theoretical relationship between clamping force (CF) and leaf resistance (R), capacitive reactance (XC), inductive reactance (XL), impedance (Z), and capacitance (C) were exposed as 3-parameter exponential decay and linear models based on bioenergetics, respectively, for mangrove species. The intracellular water metabolism parameters and salt transport characteristics were also determined based on mechanical equations with influences of Sodium nitroprusside (SNP) and rewatering (RW). The results show that the inherent capacitance and effective thickness could better represent Aegiceras corniculatum (A. corniculatum) species, and inherent resistance and impedance show obvious effects on Kandelia obovate (K. obovate) species at different salt levels. SNP application shows positive effect on different salt-resistance capacities of A. corniculatum, while K. obovate perform better in RW phase at high salt level. These outcomes indicates that K. obovate is more salt-resistant because RW process is consistent with actual situation, and response of A. corniculatum at high salt stress is irreversible, even in RW. It is concluded that the electrophysiological parameters could be used for the determination of salt-resistant capacities, which gave more enhanced and reliable information of mangroves' life activities.
Asunto(s)
Primulaceae , Rhizophoraceae , Nitroprusiato/farmacología , Primulaceae/fisiología , Rhizophoraceae/fisiología , Estrés Salino , AguaRESUMEN
Soldanella alpina differing in leaf epidermal UV-A absorbance (DEA375), as measured with the Dualex, was investigated as a model alpine plant for the flavonoid (Flav) composition and concentration and for anatomical and pigment characteristics. In sun leaves, twenty-three flavones were characterised by their mass formula, their maximum absorption, their glycosylation, their methylation and dehydroxylation pattern. The flavones belonged to four subfamilies (tetra-hydroxy-flavones, penta-hydroxy-flavones, penta-hydroxy-methyl-flavones and tri-hydroxy-di-methoxy-flavones), abundant in sun and shade leaves. Their concentration was estimated by their absorption at 350 nm after HPLC separation. Sun leaves contained relatively higher contents of penta-hydroxy-methyl-flavones and shade leaves higher contents of tetra-hydroxy-flavones. The flavones were present mainly in vacuoles, all over the leaf. After shade-sun transfer, the content of most flavones increased, irrespective of the presence or absence of UV radiation. Highly significant correlations with the log-transformed DEA375 suggest that DEA375 can be readily applied to predict the flavone content of S. alpina leaves. Shade-sun transfer of leaves decreased the hydroxycinnamic acid (HCA) content, the mass-based chlorophyll (Chl) a+b content and the Chl/Carotenoid (Car) ratio but increased DEA375, and the Car content. Together with previously reported anatomical characteristics all these parameters correlated significantly with the DEA375. The Flav content is therefore correlated to most of the structural characteristics of leaf acclimation to light and this can be probed in situ by DEA375.
Asunto(s)
Aclimatación , Hojas de la Planta/fisiología , Primulaceae/fisiología , Rayos Ultravioleta , Carotenoides/análisis , Clorofila/análisis , Flavonoides/análisis , Fotosíntesis , Hojas de la Planta/efectos de la radiación , Primulaceae/efectos de la radiación , Luz SolarRESUMEN
Salt stress is harmful to plants, especially for those that live under conditions of intense salt aport. For this reason, several species present alternatives to prevent or diminish the damages that high salt concentrations may cause to the cells. Salt glands are one of these alternatives once they are specialized structures that secrete salt. Here, we aimed to investigate if the glandular trichomes in the leaves of Jacquinia armillaris are salt glands. Anatomical and ultrastructural observations showed that the glandular trichomes in J. armillaris resemble the salt glands from other recretohalophytes Primulaceae, such as, their occurrence in sunken regions in the leaf epidermis, the presence of a large basal cell that acts as a collecting cell, the detachment of the cuticle from the outer periclinal walls forming a cuticular chamber, the thickness of the cuticle in the stalk portion of the trichome, and the presence of sodium and chloride ions in the secretion and in the xylem. Altogether, the gathered results support the hypothesis that the glandular trichomes in J. armillaris are adapted to salt secretion, thus characterizing as salt glands.
Asunto(s)
Primulaceae/fisiología , Glándula de Sal/fisiología , Animales , Hojas de la Planta/fisiología , Hojas de la Planta/ultraestructura , Primulaceae/anatomía & histología , Primulaceae/ultraestructura , Glándula de Sal/ultraestructura , Tricomas/fisiología , Tricomas/ultraestructuraRESUMEN
In the French Alps, Soldanella alpina (S. alpina) grow under shade and sun conditions during the vegetation period. This species was investigated as a model for the dynamic acclimation of shade leaves to the sun under natural alpine conditions, in terms of photosynthesis and leaf anatomy. Photosynthetic activity in sun leaves was only slightly higher than in shade leaves. The leaf thickness, the stomatal density and the epidermal flavonoid content were markedly higher, and the chlorophyll/flavonoid ratio was significantly lower in sun than in shade leaves. Sun leaves also had a more oxidised plastoquinone pool, their PSII efficiency in light was higher and their non-photochemical quenching (NPQ) capacity was higher than that of shade leaves. Shade-sun transferred leaves increased their leaf thickness, stomatal density and epidermal flavonoid content, while their photosynthetic activity and chlorophyll/flavonoid ratio declined compared to shade leaves. Parameters indicating protection against high light and oxidative stress, such as NPQ and ascorbate peroxidase, increased in shade-sun transferred leaves and leaf mortality increased. We conclude that the dynamic acclimation of S. alpina leaves to high light under alpine conditions mainly concerns anatomical features and epidermal flavonoid acclimation, as well as an increase in antioxidative protection. However, this increase is not large enough to prevent damage under stress conditions and to replace damaged leaves.
Asunto(s)
Aclimatación , Fotosíntesis , Primulaceae/fisiología , Luz Solar , Clorofila , Estrés Oxidativo , Hojas de la PlantaRESUMEN
What causes the disparity in biodiversity among regions is a fundamental question in biogeography, ecology, and evolutionary biology. Evolutionary and biogeographic processes (speciation, extinction, dispersal) directly determine species richness patterns, and can be studied using integrative phylogenetic approaches. However, the strikingly high richness of East Asia relative to other Northern Hemisphere regions remains poorly understood from this perspective. Here, for the first time, we test two general hypotheses (older colonization time, faster diversification rate) to explain this pattern, using the plant tribe Lysimachieae (Primulaceae) as a model system. We generated a new time-calibrated phylogeny for Lysimachieae (13 genes, 126 species), to estimate colonization times and diversification rates for each region and to test the relative importance of these two factors for explaining regional richness patterns. We find that neither time nor diversification rates alone explain richness patterns among regions in Lysimachieae. Instead, a new index that combines both factors explains global richness patterns in the group and their high East Asian biodiversity. Based on our results from Lysimachieae, we suggest that the high richness of plants in East Asia may be explained by a combination of older colonization times and faster diversification rates in this region.
Asunto(s)
Biodiversidad , Filogenia , Primulaceae/fisiología , Asia Oriental , Filogeografía , Primulaceae/genéticaRESUMEN
Mangroves in hypersaline coastal habitats are under constant high xylem tension and face great risk of hydraulic dysfunction. To investigate the relationships between functional traits and salt management, we measured 20 hydraulic and photosynthetic traits in four salt-adapted (SA) and two non-SA (NSA) mangrove tree species in south China. The SA species included two salt secretors (SSs), Avicennia marina (Forsskål) Vierhapper and Aegiceras corniculatum (L.) Blanco and two salt excluders (SEs), Bruguiera gymnorrhiza (L.) Savigny and Kandelia obovata (L.) Sheue et al. The two NSA species were Hibiscus tiliaceus (L.) and Pongamia pinnata (L.) Merr. Extremely high xylem cavitation resistance, indicated by water potential at 50% loss of xylem conductivity (Ψ50; -7.85 MPa), was found in SEs. Lower cavitation resistance was observed in SSs, and may result from incomplete salt removal that reduces the magnitude of xylem tension required to maintain water uptake from the soil. Surprisingly, the NSA species, P. pinnata, had very low Ψ50 (-5.44 MPa). Compared with NSAs, SAs had lower photosynthesis, vessel density, hydraulic conductivity and vessel diameter, but higher sapwood density. Eight traits were strongly associated with species' salt management strategies, with predawn water potential (ΨPD) and mean vessel diameter accounting for 95% flow (D95) having the most significant association; D95 separated SAs from NSAs and SEs had the lowest ΨPD. There was significant coupling between hydraulic traits and carbon assimilation traits. Instead of hydraulic safety being compromised by xylem efficiency, mangrove species with higher safety had higher efficiency and greater sapwood density (ρSapwood), but there was no relationship between ρSapwood and efficiency. Principal component analysis differentiated the species of the three salt management strategies by loading D, D95 and vessel density on the first axis and loading ΨPD, Ψ50 and water potential at 12% loss of xylem conductivity (Ψ12), ρSapwood and quantum yield on the second axis. Our results provide the first comparative characterization of hydraulic and photosynthetic traits among mangroves with different salt management strategies.
Asunto(s)
Avicennia/fisiología , Hibiscus/fisiología , Hojas de la Planta/fisiología , Tallos de la Planta/fisiología , Pongamia/fisiología , Primulaceae/fisiología , Rhizophoraceae/fisiología , Xilema/fisiología , China , Árboles , Agua/fisiologíaRESUMEN
BACKGROUND AND AIMS: Soil fertility and topographic microclimate are common determinants of plant species distributions. However, biotic conditions also vary along these abiotic gradients, and may mediate their effects on plants. In this study, we investigated whether soils and topographic microclimate acted directly on the performance of a focal understorey plant, or indirectly via changing biotic conditions. METHODS: We examined direct and indirect relationships between abiotic variables (soil fertility and topographic microclimate) and biotic factors (overstorey and understorey cover, litter depth and mycorrhizal colonization) and the occurrence, density and flowering of a common understorey herb, Trientalis latifolia, in the Klamath-Siskiyou Mountains, Oregon, USA. RESULTS: We found that the positive effects of soil fertility on Trientalis occurrence were mediated by greater overstorey shading and deeper litter. However, we did not find any effects of topographic microclimate on Trientalis distribution that were mediated by the biotic variables we measured. The predictive success of Trientalis species distribution models with soils and topographic microclimate increased by 12 % with the addition of the biotic variables. CONCLUSIONS: Our results reinforce the idea that species distributions are the outcome of interrelated abiotic gradients and biotic interactions, and suggest that biotic conditions, such as overstorey density, should be included in species distribution models if data are available.
Asunto(s)
Primulaceae/fisiología , Ecología , Micorrizas/metabolismo , Primulaceae/crecimiento & desarrollo , Reproducción/fisiología , Suelo , Microbiología del Suelo , Luz SolarRESUMEN
A new species, Lysimachia huangsangensis (Primulaceae), from Hunan, China is described and illustrated. The new species is closely related to L. carinata because of the crested calyx, but differs in the leaf blades that are ovate to elliptic and (3-)4.5-9 × 2-3.4 cm, 2-5-flowered racemes, and the calyx lobes that are ovate-lanceolate and 5-6 × 3-4 mm. The systematic placement and conservation status are also discussed.
Asunto(s)
ADN de Plantas/análisis , Primulaceae/clasificación , China , Filogenia , Hojas de la Planta/genética , Primulaceae/genética , Primulaceae/fisiología , Análisis de Secuencia de ADN/métodosRESUMEN
Drought stress is one of the major abiotic stresses that affects plant growth and metabolism adversely around the world. According to this research, the effect of drought stress on the activity of antioxidative enzymes, soluble sugar, protein and lipid peroxidation were studied in leaves of two mangrove plants, Kandelia obovata and Aegiceras corniculatum. The result showed that superoxide dismutase (SOD) and peroxidase (POD) varied significantly between the leaves and roots studied. The activities increased in different stress levels. The production rate of O 2 (-·) changed with the activity of SOD and POD. Lipid peroxidation was enhanced and Glycine betaine (GB) could decrease the level of malonaldehyde in order to reduce the damage of membrane system. The content of soluble sugar and protein also increased under drought stress and GB helped to eliminate the accumulation of them which somehow enhance the ability of defensing the plants under drought stress. These results indicated that antioxidative activity may play an important role in A. corniculatum and K. obovata and that cell membrane in leaves of K. obovata had greater stability than those of A. corniculatum. Exogenous application of GB had positive effects on A. corniculatum and K. obovata under drought stress which could be products exogenously applied to mangrove plants in order to alleviates the adverse effects.
Asunto(s)
Antioxidantes/metabolismo , Sequías , Primulaceae/fisiología , Rhizophoraceae/fisiología , Metabolismo de los Hidratos de Carbono , Peroxidación de Lípido , Concentración Osmolar , Oxidación-Reducción , Hojas de la Planta/enzimología , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/fisiología , Proteínas de Plantas/metabolismo , Primulaceae/enzimología , Primulaceae/crecimiento & desarrollo , Rhizophoraceae/enzimología , Rhizophoraceae/crecimiento & desarrollo , Estrés FisiológicoRESUMEN
Although the cold-resistant ability of mangroves varies greatly with species, the physiological mechanism remains unclear. The chilling stress effects on morphological changes, photosynthetic pigments, reactive oxygen species (ROS), malondialdehyde (MDA) and several antioxidants, were studied in leaves of three mangrove seedlings (Kandelia obovata, Aegiceras corniculatum and Avicennia marina). Results showed that both K. obovata and A. corniculatum exhibited lighter chilling damage, lower chilling injury rates and higher survival rates compared to A. marina. Reductions of chlorophylls (Chls) were observed in all the three mangroves, and the highest was detected in A. marina. Significant increases in content of ROS (hydrogen peroxide, H2O2; hydroxyl radicals, OHâ ) and MDA were observed in both A. marina and A. corniculatum, whereas chilling stressed K. obovata showed a decrease in H2O2 content, constant OHâ level and instantaneous increase of MDA. The contents of proline and water-soluble protein exhibited similar stress-time dependent increases in all mangroves, while A. corniculatum showed the highest increase of proline and relatively higher increase of water-soluble protein. The catalase activities significantly decreased with stress time in all mangroves, while K. obovata showed the least reduction. An increase in ascorbic acid (AsA) content and activities of superoxide dismutase, peroxidase (POD), and ascorbate peroxidase (APX) were also detected in all the three mangroves, while K. obovata showed the highest increases. These results indicate that chilling-tolerance of mangroves is associated with the efficiency of antioxidants, as confirmed by principal component analysis. The AsA, APX and POD in K. obovata may play more important role in control of oxidative stresses than those in the other two species. Furthermore, the higher cold-resistance of A. corniculatum compared to A. marina may be partly associated with its higher proline accumulation. The results indicate that enzymatic and non-enzymatic antioxidants (POD, APX, AsA, proline and Car) play key roles in scavenging of excess ROS in mangroves. Further studies focusing on these stress-responsive genes will enable better understanding of the cold-resistance mechanism from molecular level.
Asunto(s)
Avicennia/fisiología , Frío , Primulaceae/fisiología , Rhizophoraceae/fisiología , Hojas de la Planta/fisiología , Análisis de Componente Principal , Plantones/fisiologíaRESUMEN
Gene expression studies could provide insight into the physiological mechanisms and strategies used by plants under stress conditions. Selection of suitable internal control gene(s) is essential to accurately assess gene expression levels. For the mangrove plant, Aegiceras corniculatum, reliable reference genes to normalize real-time quantitative PCR data have not been previously investigated. In this study, the expression stabilities of five candidate reference genes [glyceraldehydes-3-phosphate dehydrogenase (GAPDH), 18SrRNA, ß-Actin, 60S ribosomal protein L2, and elongation factor-1-A] were determined in leaves of A. corniculatum treated by cold, drought, salt, heavy metals, and pyrene and in different tissues of A. corniculatum under normal condition. Two software programs (geNorm and NormFinder) were employed to analyze and rank the tested genes. Results showed that GAPDH was the most suitable reference gene in A. corniculatum and the combination of two or three genes was recommended for greater accuracy. To assess the value of these tested genes as internal controls, the relative quantifications of CuZnSOD gene were also conducted. Results showed that the relative expression levels of CuZnSOD gene varied depending on the internal reference genes used, which highlights the importance of the choice of suitable internal controls in gene expression studies. Furthermore, the results also confirmed that GAPDH was a suitable reference gene for qPCR normalization in A. corniculatum under abiotic stresses. Identification of A. corniculatum reference gens in a wide range of experimental samples will provide a useful reference in future gene expression studies in this species, particularly involving similar stresses.
Asunto(s)
Expresión Génica , Proteínas de Plantas/genética , Primulaceae/genética , Estrés Fisiológico/genética , Datos de Secuencia Molecular , Proteínas de Plantas/metabolismo , Primulaceae/enzimología , Primulaceae/fisiología , Reacción en Cadena en Tiempo Real de la Polimerasa , Análisis de Secuencia de ADN , Distribución TisularRESUMEN
The exceptional species diversity of flowering plants, exceeding that of their sister group more than 250-fold, is especially evident in floral innovations, interactions with pollinators and sexual systems. Multiple theories, emphasizing flower-pollinator interactions, genetic effects of mating systems or high evolvability, predict that floral evolution profoundly affects angiosperm diversification. However, consequences for speciation and extinction dynamics remain poorly understood. Here, we investigate trajectories of species diversification focusing on heterostyly, a remarkable floral syndrome where outcrossing is enforced via cross-compatible floral morphs differing in placement of their respective sexual organs. Heterostyly evolved at least 20 times independently in angiosperms. Using Darwin's model for heterostyly, the primrose family, we show that heterostyly accelerates species diversification via decreasing extinction rates rather than increasing speciation rates, probably owing to avoidance of the negative genetic effects of selfing. However, impact of heterostyly appears to differ over short and long evolutionary time-scales: the accelerating effect of heterostyly on lineage diversification is manifest only over long evolutionary time-scales, whereas recent losses of heterostyly may prompt ephemeral bursts of speciation. Our results suggest that temporal or clade-specific conditions may ultimately determine the net effects of specific traits on patterns of species diversification.
Asunto(s)
Biodiversidad , Evolución Biológica , Primulaceae/fisiología , Proteínas de Cloroplastos/genética , Extinción Biológica , Flores/genética , Flores/fisiología , Datos de Secuencia Molecular , Filogenia , Reacción en Cadena de la Polimerasa , Primulaceae/genética , Reproducción , Análisis de Secuencia de ADNRESUMEN
A split plot 3 by 4 experiment was designed to investigate and distinguish the relationships among production of secondary metabolites, soluble sugar, phenylalanine ammonia lyase (PAL; EC 4.3.1.5) activity, leaf gas exchange, chlorophyll content, antioxidant activity (DPPH), and lipid peroxidation under three levels of CO2 (400, 800, and 1200 µ mol/mol) and four levels of light intensity (225, 500, 625, and 900 µ mol/m(2)/s) over 15 weeks in Labisia pumila. The production of plant secondary metabolites, sugar, chlorophyll content, antioxidant activity, and malondialdehyde content was influenced by the interactions between CO2 and irradiance. The highest accumulation of secondary metabolites, sugar, maliondialdehyde, and DPPH activity was observed under CO2 at 1200 µ mol/mol + light intensity at 225 µ mol/m(2)/s. Meanwhile, at 400 µ mol/mol CO2 + 900 µ mol/m(2)/s light intensity the production of chlorophyll and maliondialdehyde content was the highest. As CO2 levels increased from 400 to 1200 µ mol/mol the photosynthesis, stomatal conductance, f v /f m (maximum efficiency of photosystem II), and PAL activity were enhanced. The production of secondary metabolites displayed a significant negative relationship with maliondialdehyde indicating lowered oxidative stress under high CO2 and low irradiance improved the production of plant secondary metabolites that simultaneously enhanced the antioxidant activity (DPPH), thus improving the medicinal value of Labisia pumila under this condition.
Asunto(s)
Antioxidantes/metabolismo , Dióxido de Carbono/farmacología , Fotosíntesis/fisiología , Primulaceae/fisiología , Metabolismo Secundario/fisiología , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta en la Radiación , Luz , Fotosíntesis/efectos de los fármacos , Fotosíntesis/efectos de la radiación , Primulaceae/efectos de los fármacos , Primulaceae/efectos de la radiación , Dosis de Radiación , Metabolismo Secundario/efectos de los fármacos , Metabolismo Secundario/efectos de la radiaciónRESUMEN
Lysimachia vulgaris L. (yellow loosestrife) is a medicinal plant that has been used in the treatment of fever, ulcer, diarrhea and wounds in traditional medicine. A reliable in vitro culture protocol for yellow loosestrife was established. Explants (leaf lamina, stem internode and root segments) were cultured on Murashige and Skoog minimal organics (MSMO) medium supplemented with various plant growth regulator combinations. Of the tested combinations, those involving benzyladenine (BA) with either indole-3-acetic acid (IAA) or indole-3-butyric acid (IBA) were the most effective for all used explants in shoot production. Best shoot proliferation was obtained from leaf lamina explant cultured on media containing 0.5 mg/l BA and 0.1, 0.5 or 1 mg/l IBA, from stem internode explant cultured on media containing 1 mg/l BA and 0.5 mg/l IBA or 0.01 mg/l thidiazuron (TDZ) and 0.5 mg/l IAA, and from root explant cultured on media containing 0.5 mg/l BA and 0.5 mg/l IAA. Regenerated shoots were rooted on MSMO medium containing different concentrations of IAA, IBA, 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene acetic acid (NAA). IBA was determined as the most effective auxin for rooting. Most shoots developed roots on medium with 0.5 mg/l IBA.
Asunto(s)
Hojas de la Planta/fisiología , Raíces de Plantas/fisiología , Tallos de la Planta/fisiología , Plantas Medicinales/fisiología , Primulaceae/fisiología , Regeneración/fisiología , Reguladores del Crecimiento de las Plantas/farmacología , Regeneración/efectos de los fármacosRESUMEN
A randomized complete block design experiment was designed to characterize the relationship between production of total flavonoids and phenolics, anthocyanin, photosynthesis, maximum efficiency of photosystem II (Fv/Fm), electron transfer rate (Fm/Fo), phenyl alanine lyase activity (PAL) and antioxidant (DPPH) in Labisia pumila var. alata, under four levels of irradiance (225, 500, 625 and 900 µmol/m(2)/s) for 16 weeks. As irradiance levels increased from 225 to 900 µmol/m(2)/s, the production of plant secondary metabolites (total flavonoids, phenolics and antocyanin) was found to decrease steadily. Production of total flavonoids and phenolics reached their peaks under 225 followed by 500, 625 and 900 µmol/m(2)/s irradiances. Significant positive correlation of production of total phenolics, flavonoids and antocyanin content with Fv/Fm, Fm/Fo and photosynthesis indicated up-regulation of carbon-based secondary metabolites (CBSM) under reduced photoinhibition on the under low light levels condition. At the lowest irradiance levels, Labisia pumila extracts also exhibited a significantly higher antioxidant activity (DPPH) than under high irradiance. The improved antioxidative activity under low light levels might be due to high availability of total flavonoids, phenolics and anthocyanin content in the plant extract. It was also found that an increase in the production of CBSM was due to high PAL activity under low light, probably signifying more availability of phenylalanine (Phe) under this condition.
Asunto(s)
Antioxidantes/metabolismo , Flavonoides/metabolismo , Fenoles/metabolismo , Fotosíntesis , Primulaceae/fisiología , Antocianinas/química , Antocianinas/metabolismo , Antioxidantes/química , Flavonoides/química , Luz , Fenoles/química , Fenilanina Amoníaco-Liasa/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Primulaceae/química , Primulaceae/enzimologíaRESUMEN
Relatively, few species have been able to colonize extremely cold alpine environments. We investigate the role played by the cushion life form in the evolution of climatic niches in the plant genus Androsace s.l., which spreads across the mountain ranges of the Northern Hemisphere. Using robust methods that account for phylogenetic uncertainty, intraspecific variability of climatic requirements and different life-history evolution scenarios, we show that climatic niches of Androsace s.l. exhibit low phylogenetic signal and that they evolved relatively recently and punctually. Models of niche evolution fitted onto phylogenies show that the cushion life form has been a key innovation providing the opportunity to occupy extremely cold environments, thus contributing to rapid climatic niche diversification in the genus Androsace s.l. We then propose a plausible scenario for the adaptation of plants to alpine habitats.
Asunto(s)
Evolución Biológica , Ecosistema , Primulaceae/anatomía & histología , Primulaceae/fisiología , Adaptación Fisiológica , Altitud , Proteínas de Cloroplastos/genética , Clima , ADN Intergénico/genética , Genes de Plantas , Filogenia , Primulaceae/clasificación , Primulaceae/genética , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
A sand culture pot experiment was conducted to study the eco-physiological responses of high-latitude transplanted mangrove Aegiceras corniculatum seedlings to varying concentration of NaCl (0, 100, 200, 300, and 400 mmol x L(-1)). Under the stress of 100 mmol NaCl x L(-1), the seedling growth was slightly promoted; whereas at 300 mmol NaCl x L(-1), the plant height, stem basal diameter, fresh and dry mass, and root/shoot ratio were decreased significantly. High salt stress inhibited the leaf superoxide dismutase (SOD) and peroxidase (POD) activities, increased the leaf malondialdehyde (MDA) content, and decreased the leaf chlorophyll and carotenoids contents as well as the total soluble sugar and free amino acid contents in different organs. Under the stress of different concentration NaCl, the Na+ contents in leaf, stem, and root increased rapidly while the K+ contents had a relatively decrease, resulting in a rapid decrease of K+/Na+ ratio and an imbalance between K+ and Na+ in A. corniculatum vegetative organs. When the NaCl concentration in the medium was higher than 300 mmol x L(-1), the C and N metabolism of A. corniculatum vegetative organs was maladjusted, which inhibited the normal growth of the seedlings, resulting in a significant decrease in the plant height and fresh and dry mass.
Asunto(s)
Primulaceae/crecimiento & desarrollo , Primulaceae/fisiología , Plantones/fisiología , Cloruro de Sodio/farmacología , Estrés Fisiológico , Ecosistema , Agricultura Forestal/métodos , Geografía , Plantones/crecimiento & desarrollo , TrasplantesRESUMEN
The significance of total glutathione content was investigated in two alpine plant species with highly differing antioxidative scavenging capacity. Leaves of Soldanella alpina and Ranunculus glacialis incubated for 48 h in the presence of buthionine-sulfoximine had 50% lower glutathione contents when compared with leaves incubated in water. The low leaf glutathione content was not compensated for by activation of other components involved in antioxidative protection or electron consumption. However, leaves with normal but not with low glutathione content increased their ascorbate content during high light (HL) treatment (S. alpina) or catalase activity at low temperature (LT) (R. glacialis), suggesting that the mere decline of the leaf glutathione content does not act as a signal to ameliorate antioxidative protection by alternative mechanisms. CO(2)-saturated oxygen evolution was not affected in glutathione-depleted leaves at various temperatures, except at 35°C, thereby increasing the high temperature (HT) sensitivity of both alpine species. Leaves with low and normal glutathione content were similarly resistant to photoinhibition and photodamage during HL treatment at ambient temperature in the presence and absence of paraquat or at LT. However, HL- and HT-induced photoinhibition increased in leaves with low compared to leaves with normal glutathione content, mainly because the recovery after heat inactivation was retarded in glutathione-depleted leaves. Differences in the response of photosystem II (PSII) activity and CO(2)-saturated photosynthesis suggest that PSII is not the primary target during HL inactivation at HT. The results are discussed with respect to the role of antioxidative protection as a safety valve for temperature extremes to which plants are not acclimated.
Asunto(s)
Glutatión/metabolismo , Primulaceae/fisiología , Ranunculus/fisiología , Aclimatación , Antioxidantes/metabolismo , Ácido Ascórbico/metabolismo , Catalasa/metabolismo , Frío , Glutatión/biosíntesis , Luz , Fotosíntesis/fisiología , Complejo de Proteína del Fotosistema II/metabolismo , Hojas de la Planta/química , Primulaceae/metabolismo , Ranunculus/metabolismoRESUMEN
The association between bacteria and leaves in Ardisia has been described as a cyclic and obligate symbiosis in which bacteria are maintained throughout all stages of the plant's life cycle to guarantee normal growth and survival of the host. This intimate interaction suggests that both partners have co-diversified together. To test this co-speciation hypothesis, we constructed an endosymbiont (16S rDNA and gyrB) and host (rps16, trnL, matK and ITS) phylogeny. Phylogenetic analyses of the endosymbionts revealed a pattern of strict host specificity and recovered a single clade in the genus Burkholderia (ß-proteobacteria), which was closely related to the endosymbionts of leaf-nodulated Rubiaceae. Comparison of symbiont and host phylogenies suggests a single origin of bacterial leaf symbiosis in the nodulated ancestor of Ardisia and does not reject the co-speciation hypothesis.