RESUMEN
In eukaryotes, the STRUCTURAL MAINTENANCE OF CHROMOSOME 5/6 (SMC5/6) complex is critical to maintaining chromosomal structures around double-strand breaks (DSBs) in DNA damage repair. However, the recruitment mechanism of this conserved complex at DSBs remains unclear. In this study, using Arabidopsis thaliana as a model, we found that SMC5/6 localization at DSBs is dependent on the protein scaffold containing INVOLVED IN DE NOVO 2 (IDN2), CELL DIVISION CYCLE 5 (CDC5), and ALTERATION/DEFICIENCY IN ACTIVATION 2B (ADA2b), whose recruitment is further mediated by DNA-damage-induced RNAs (diRNAs) generated from DNA regions around DSBs. The physical interactions of protein components including SMC5-ADA2b, ADA2b-CDC5, and CDC5-IDN2 result in formation of the protein scaffold. Further analysis indicated that the DSB localization of IDN2 requires its RNA-binding activity and ARGONAUTE 2 (AGO2), indicating a role for the AGO2-diRNA complex in this process. Given that most of the components in the scaffold are conserved, the mechanism presented here, which connects SMC5/6 recruitment and small RNAs, will improve our understanding of DNA repair mechanisms in eukaryotes.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Roturas del ADN de Doble Cadena , Daño del ADN/genética , Reparación del ADN/genética , ADN de Plantas/metabolismo , ARN/genética , Factores de Transcripción/metabolismoRESUMEN
Increasing amounts of experimental evidence show that anthocyanins provide physiological protection to plants under stress. However, the difference in photoprotection mediated by anthocyanins and other photoprotective substances in different seasons is still uncertain. To determine the relationship between anthocyanin accumulation and the photoprotective effects in different seasons, Castanopsis chinensis and Acmena acuminatissima, whose anthocyanin accumulation patterns differ in different seasons, were used as materials to explain how plants adapt to different seasons; as such, their physiological and biochemical responses were analyzed. Young leaves of C. chinensis and A. acuminatissima presented different colors in the different seasons. In summer, the young leaves of C. chinensis were purplish red, while those of A. acuminatissima were light green. In winter, the young leaves of C. chinensis were light green, while those of A. acuminatissima were red. Compared with the young red leaves, the young light green leaves that did not accumulate anthocyanins had higher flavonoid and phenolics contents, total antioxidant capacity, non-photochemical quenching (NPQ), and relative membrane leakage, and a slower recovery rate in the maximum photochemical efficiency (Fv/Fm) after high-light treatment. In addition, the net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (gs), and the effective quantum yield of PSII (ΦPSII) of the young leaves in winter were significantly lower than those in summer, while the activities of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), and superoxide dismutase (SOD, EC 1.15.1.1) were significantly higher than those in summer. These data indicate that to adapt to seasonal changes anthocyanins, other antioxidative substances and antioxidative enzymes, as well as components involved in the safe dissipation of excitation energy as heat need to cooperate with one another.
Asunto(s)
Adaptación Ocular/fisiología , Antocianinas/metabolismo , Fagaceae/metabolismo , Myrtaceae/metabolismo , Pigmentación/fisiología , Hojas de la Planta/metabolismo , Estaciones del Año , Luz Solar/efectos adversos , Antioxidantes/metabolismo , China , Fenotipo , Fotosíntesis/fisiologíaRESUMEN
Biological invasion is a hot topic in ecological research. Most studies on the physiological mechanisms of plants focus on leaves, but few studies focus on stems. To study the tolerance of invasive plant (Sphagneticola trilobata L.) to low temperature, relevant physiological indicators (including anthocyanin and chlorophyll) in different organs (leaves and stems) were analyzed, using a native species (Sphagneticola calendulacea L.) as the control. The results showed that, upon exposure to low temperature for 15 days, the stems of two Sphagneticola species were markedly reddened, their anthocyanin content increased, chlorophyll and chlorophyll fluorescence parameters decreased, and the accumulation of reactive oxygen species in the stem increased. The percentage increases of antioxidants and total antioxidant capacities in stems were significantly higher in S. trilobata than in S. calendulacea. This showed that S. trilobata had higher cold tolerance in stems while leaves were opposite. To further verify the higher cold tolerance of the stem of S. trilobata, a defoliation experiment was designed. We found that the defoliated stem of S. trilobata reduced anthocyanin accumulation and increased chlorophyll content, while alleviating membrane lipid damage and electrical conductivity, and the defoliated stem still showed an increase in stem diameter and biomass under low temperature. The discovery of the physiological and adaptive mechanisms of the stem of S. trilobata to low temperature will provide a theoretical basis for explaining how S. trilobata maintains its annual growth in South China. This is of great significance for predicting the future spread of cloned and propagated invasive plants.
Asunto(s)
Adaptación Fisiológica , Asteraceae/fisiología , Frío/efectos adversos , Fotosíntesis/fisiología , Hojas de la Planta/fisiología , Tallos de la Planta/fisiología , Malezas/fisiología , China , Especies IntroducidasRESUMEN
Anthocyanins are water-soluble pigments in plants known for their photoprotective role against photoinhibitory and photooxidative damage under high light (HL). However, it remains unclear whether light-shielding or antioxidant activity plays a major role in the photoprotection exerted by anthocyanins under HL stress. To shed light on this question, we analyzed the physiological and biochemical responses to HL of three Arabidopsis thaliana lines (Col, chi, ans) with different light absorption and antioxidant characteristics. Under HL, ans had the highest antioxidant capacity, followed by Col, and finally chi; Col had the strongest light attenuation capacity, followed by chi, and finally ans. The line ans had weaker physiological activity of chloroplasts and more severe oxidative damage than chi after HL treatment. Col with highest photoprotection of light absorption capacity had highest resistance to HL among the three lines. The line ans with high antioxidant capacity could not compensate for its disadvantages in HL caused by the absence of the light-shielding function of anthocyanins. In addition, the expression level of the Anthocyanin Synthase (ANS) gene was most upregulated after HL treatment, suggesting that the conversion of colorless into colored anthocyanin precursors was necessary under HL. The contribution of anthocyanins to flavonoids, phenols, and antioxidant capacity increased in the late period of HL, suggesting that plants prefer to synthesize red anthocyanins (a group of colored antioxidants) over other colorless antioxidants to cope with HL. These experimental observations indicate that the light attenuation role of anthocyanins is more important than their antioxidant role in photoprotection.
Asunto(s)
Adaptación Ocular/fisiología , Antocianinas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Hojas de la Planta/metabolismo , Protección Radiológica , Luz Solar/efectos adversos , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Variación Genética , Genotipo , Mutación , Estrés Oxidativo/fisiología , Fenotipo , Fotosíntesis/fisiologíaRESUMEN
The screening and identification of hyperaccumulators is the key to the phytoremediation of soils contaminated by heavy metal (HM). Arbuscular mycorrhizal fungus (AMF) can improve plant growth and tolerance to HM; therefore, AMF-assisted phytoextraction has been regarded as a potential technique for the remediation of HM-polluted soils. A greenhouse pot experiment was conducted to determine whether Sphagneticola calendulacea is a Cd-hyperaccumulator and to investigate the effect of the AMF-Funneliformis mosseae (FM) on plant growth and on the accumulation, subcellular distribution and chemical form of Cd in S. calendulacea grown in soils supplemented with different Cd levels. At 25, 50 and 100 mg Cd kg-1 level, S. calendulacea showed high Cd tolerance, the translocation factor and the bioconcentration factor exceeded 1, and accumulation of more than 100 mg Cd kg-1 was observed in the aboveground parts of the plant, meeting the requirements for a Cd-hyperaccumulator. Moreover, FM colonization significantly increased both biomasses and Cd concentration in S. calendulacea. After FM inoculation, the Cd concentrations and proportions increased in the cell walls, but exhibited no significant change in the organelles of the shoots. Meanwhile, FM symbiosis contributed to the conversion of Cd from highly toxic chemical forms (extracted by 80% ethanol and deionized water) to less toxic chemical forms (extracted by 1 M NaCl, 2% acetic acid, 0.6 M HCl) of Cd in the shoots. Overall, S. calendulacea is a typical Cd-hyperaccumulator, and FM symbiosis relieved the phytotoxicity of Cd and promoted plant growth and Cd accumulation, and thus greatly increasing the efficiency of phytoextraction for Cd-polluted soil. Our study provides a theoretical basis and application guidance for the remediation of Cd-contaminated soil by the symbiont of S. calendulacea with FM.
Asunto(s)
Asteraceae/metabolismo , Bioacumulación , Cadmio/metabolismo , Glomeromycota/fisiología , Micorrizas/fisiología , Contaminantes del Suelo/metabolismo , Asteraceae/crecimiento & desarrollo , Asteraceae/microbiología , Biodegradación AmbientalRESUMEN
Arbuscular mycorrhizal fungus (AMF) can relieve Cd phytotoxicity and improve plant growth, but the mechanisms involved in this process have still been not completely known. In the present work, a pot experiment was conducted to examine productions of glutathione (GSH) and phytochelatins (PCs), and absorption, chemical forms and subcellular distribution of Cd in maize (Zea mays) inoculated with or without AMF (Rhizophagus intraradices (Ri) and Glomus versiforme (Gv)) in Cd-amended soils (0, 1 and 5â¯mgâ¯Cdâ¯kg-1 soil). In general, both Ri and Gv inoculation dramatically enhanced biomass production and reduced Cd concentrations in shoots and roots of maize when compared to the non-mycorrhizal treatment. Moreover, both Ri and Gv symbiosis obviously increased contents of GSH and PCs, both in shoots and roots. Subcellular distribution of Cd in maize indicated that most of Cd (more than 90%) was accumulated in cell wall and soluble fraction. In addition, Cd proportions in soluble fractions in shoots of maize inoculated with Gv or Ri were considerably increased, but reduced in cell wall fractions compared to non-mycorrhizal maize, indicating that mycorrhizal symbiosis promoted Cd transfer to vacuoles. Furthermore, proportions of Cd in inorganic and water-soluble forms were declined, but elevated in pectates and proteins-integrated forms in mycorrhizal maize, which suggested that Gv and Ri could convert Cd into inactive forms. These observations could provide a further understanding of potential Cd detoxification mechanism in maize inoculated with AMF.
Asunto(s)
Cadmio/metabolismo , Cadmio/toxicidad , Glomeromycota , Micorrizas/metabolismo , Zea mays/metabolismo , Biomasa , Cadmio/análisis , Pared Celular/metabolismo , Glutatión/metabolismo , Fitoquelatinas/metabolismo , Desarrollo de la Planta , Raíces de Plantas/metabolismo , Brotes de la Planta/metabolismo , Suelo/química , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidad , Simbiosis , Vacuolas/metabolismo , Zea mays/crecimiento & desarrolloRESUMEN
Seagrasses play an important role in coastal marine ecosystems, but they have been increasingly threatened by human activities. In recent years, seagrass communities have rapidly degenerated in the coastal marine ecosystems of China. To identify the reasons for the decline in seagrasses, the phytotoxic effects of trace metals (Cu, Cd and Zn) on the seagrass Thalassia hemprichii were investigated, and the environmental contents of the metals were analyzed where the seagrass grows. The results showed that leaf necrosis in T. hemprichii exposed to 0.01-0.1 mg L-1 of Cu2+ for 5 days was more serious than that in plants exposed to the same concentrations of Cd2+ and Zn2+. The chlorophyll content in T. hemprichii declined in a concentration-dependent manner after 5 days of exposure to Cu2+, Cd2+ and Zn2+. The evident reduction in ΔF/Fm' in T. hemprichii leaves was observed at day 1 of exposure to 0.01-1.0 mg L-1 of Cu2+ and at day 3 of exposure to 0.1-1.0 mg L-1 of Cd2+. The antioxidant enzyme activities (SOD, POD and CAT) in T. hemprichii leaves exposed to the three metal ions also showed significant changes. In seawater from Xincun Bay (Hainan, China), where T. hemprichii grows, Cu had reached a concentration (i.e., 0.01 mg L-1) that could significantly reduce chlorophyll content and ΔF/Fm' in T. hemprichii leaves. Our results indicate that Cu influences the deterioration of seagrasses in Xincun Bay.
Asunto(s)
Clorofila/metabolismo , Hydrocharitaceae/efectos de los fármacos , Fotosíntesis , Proteínas de Plantas/metabolismo , Contaminantes Químicos del Agua/toxicidad , Cadmio/toxicidad , China , Cobre/toxicidad , Monitoreo del Ambiente , Fluorescencia , Sedimentos Geológicos/análisis , Hydrocharitaceae/crecimiento & desarrollo , Espectrometría de Masas , Fotosíntesis/efectos de los fármacos , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/crecimiento & desarrollo , Dinámica Poblacional , Agua de Mar/análisis , Zinc/toxicidadRESUMEN
The effects of Dissostichus mawsoni-Calmodulin (Dm-CaM) on growth performance, enzyme activities, respiratory burst, MDA level and immune-related gene expressions of the orange-spotted grouper (Epinephelus coioides) exposed to the acute low temperature stress were evaluated. The commercial diet supplemented with Dm-CaM protein was fed to the groupers for 6 weeks. No significant difference was observed in the specific growth rates, weight gains and survivals. After the feeding trial, the groupers were exposed to acute low temperature challenge. The groupers fed with Dm-CaM additive diet showed a significant decrease in the respiratory burst activity, while the blood cell number increased significantly at 25 °C by comparing with the control and additive control group. The enzymatic activity of SOD, ACP and ALP increased significantly in Dm-CaM additive group, while MDA level maintained stable with the lowest value. qRT-PCR analysis indicated that the up-regulated transcript expressions of CaM, C3, SOD2, LysC and HSPA4 were observed in Dm-CaM additive group. These results indicated that Dm-CaM additive diet may regulate the grouper immune response to the acute low temperature challenge.
Asunto(s)
Alimentación Animal/análisis , Calmodulina/farmacología , Frío , Proteínas de Peces/metabolismo , Perciformes/crecimiento & desarrollo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinariaRESUMEN
Many studies have investigated the photoprotective and photosynthetic capacity of plant leaves, but few have simultaneously evaluated the dynamic changes of photoprotective capacity and photosynthetic maturation of leaves at different developmental stages. As a result, the process between the decline of photoprotective substances and the onset of photosynthetic maturation during plant leaf development are still poorly understood, and the relationship between them has not been quantitatively described. In this study, the contents of photoprotective substances, photosynthetic pigment content and photosynthetic capacity of leaves at different developmental stages from young leaves to mature leaves were determined by spatio-temporal replacement in eight dominant tree species in subtropical evergreen broadleaved forests. The correlation analysis found that the data sets of anthocyanins, flavonoids, total phenolics and total antioxidant capacity were mainly distributed on one side of the symmetry axis (y = x), while the data sets of flavonoids, total phenolics and total antioxidant capacity were mainly distributed on both sides of the symmetry axis (y = x). In addition, the content of photoprotective substances in plant leaves was significantly negatively correlated with photosynthetic pigment content and photosynthetic capacity but was significantly positively correlated with dark respiration rate (Rd). When chlorophyll accumulated to ~50% of the final value, the photoprotective substance content and Rd of plant leaves reached the lowest level, and anthocyanins disappeared completely; in contrast, the photosynthetic capacity reached the highest level. Our results suggest that anthocyanins mainly play a light-shielding role in the young leaves of most plants in subtropical forests. In addition, 50% chlorophyll accumulation in most plant leaves was the basis for judging leaf photosynthetic maturity. We also believe that 50% chlorophyll accumulation is a critical period in the transition of plant leaves from high photoprotective capacity (high metabolic capacity, low photosynthetic capacity) to low photoprotective capacity (low metabolic capacity, high photosynthetic capacity).
Asunto(s)
Antocianinas , Árboles , Árboles/metabolismo , Antocianinas/metabolismo , Antioxidantes/metabolismo , Fotosíntesis , Bosques , Clorofila/metabolismo , Hojas de la PlantaRESUMEN
Photoprotection strategies that have evolved in plants to cope with high light (HL) stress provide plants with the ability to resist HL. However, it has not been clearly confirmed which photoprotection strategy is the major HL resistance mechanism. To reveal the major photoprotection mechanism against short-term high light (STHL), the physiological and biochemical responses of three Arabidopsis mutants (Col, chi and ans) under STHL were analyzed in this study. After STHL treatment, the most serious photosynthetic pigment damage was observed in chi plants. At the same time, the degrees of membrane and Rubisco damage in chi was the highest, followed by Col, and ans was the smallest. The results showed that ans with high antioxidant capacity showed higher resistance to STHL treatment than Col containing anthocyanins, while chi with no anthocyanin accumulation and small antioxidant capacity had the lowest resistance. In addition, the gene expression results showed that plants tend to synthesize anthocyanin precursor flavonoids with antioxidant capacity under STHL stress. To further determine the major mechanism of photoprotection under STHL, we also analyzed Arabidopsis lines (Col, CHS1, CHS2 and tt4) that had the same anthocyanin content but different antioxidant capacities. It was found that CHS2 with high antioxidant capacity had higher cell viability, smaller maximal quantum yield of PSII photochemistry (Fv/Fm) reduction and less reactive oxygen species (ROS) accumulation under HL treatment of their mesophyll protoplasts. Therefore, the antioxidant capacity provided by antioxidant substances was the major mechanism of plant photoprotection under STHL treatment.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Antocianinas , Antioxidantes , Luz , Hojas de la Planta , Receptores InmunológicosRESUMEN
Phenotypic plasticity affords invasive plant species the ability to colonize a wide range of habitats, but physiological plasticity of their stems is seldom recognized. Investigation of the stem plasticity of invasive plant species could lead to a better understanding of their invasiveness. We performed pot experiments involving defoliation treatments and isolated culture experiments to determine whether the invasive species Mikania micrantha exhibits greater plasticity in the stems than do three non-invasive species that co-occur in southern China and then explored the mechanism underlying the modification of its stem photosynthesis. Our results showed that the stems of M. micrantha exhibited higher plasticity in terms of either net or gross photosynthetic rate in response to the defoliation treatment. These effects were positively related to an increased stem elongation rate. The enhancement of stem photosynthesis in M. micrantha resulted from the comprehensive action involving increases in the Chl a/b ratio, D1 protein and stomatal aperture, changes in chloroplast morphology and a decrease in anthocyanins. Increased plasticity of stem photosynthesis may improve the survival of M. micrantha under harsh conditions and allow it to rapidly recover from defoliation injuries. Our results highlight that phenotypic plasticity promotes the invasion success of alien plant invaders.
RESUMEN
Theoretical and experimental studies have demonstrated that temperature is an important environmental factor that affects the regional distribution of plants. However, how to modify the distribution pattern of plants in different regions is a focus of current research. Obtain the information of cold tolerance genes from cold tolerance species, cloning genes with real cold tolerance effects is one of the most important ways to find the genes related to cold tolerance. In this study, we investigated whether transferring the VHA-c gene from Antarctic notothenioid fishes into Arabidopsis enhances freezing tolerance of Arabidopsis. The physiological response and molecular changes of VHA-c overexpressing pedigree and wildtype Arabidopsis were studied at -20 °C. The results showed that the malondialdehyde (MDA) and membrane leakage rates of WT plants were significantly higher than those of VHA-c8 and VHA-c11 plants, but the soluble sugar, soluble protein, proline and ATP contents of WT plants were significantly lower than those of VHA-c8 and VHA-c11 plants under -20 °C freezing treatment. The survival rate, VHA-c gene expression level and VHA-c protein contents of WT plants were significantly lower than those of VHA-c8 and VHA-c11 plants under -20 °C freezing treatment. Correlation analysis showed that ATP content was significantly negatively correlated with MDA and membrane leakage rate, and positively correlated with soluble sugar, soluble protein and proline content under -20 °C freezing treatment. These results demonstrated that overexpression of the VHA-c gene provided strong freezing tolerance to Arabidopsis by increasing the synthesis of ATP and improved the adaptability of plants in low temperature environment.
Asunto(s)
Arabidopsis/fisiología , Proteínas de Peces/fisiología , Peces/genética , Congelación , ATPasas de Translocación de Protón Vacuolares/fisiología , Animales , Regiones Antárticas , Arabidopsis/genética , Frío , Proteínas de Peces/genética , Regulación de la Expresión Génica de las Plantas , Plantas Modificadas Genéticamente/fisiología , ATPasas de Translocación de Protón Vacuolares/genéticaRESUMEN
Differences in plant shade tolerance constitute a major mechanism driving the succession of forest communities in subtropical forests. However, the indirect effects of differences in light requirements on the growth of mid- and late-successional tree species are unclear, and this potential growth effect has not been explained at the transcriptome level. Here, a typical mid-successional dominant tree species, Schima superba Gardn. et Champ, and a typical late-successional dominant tree species, Cryptocarya concinna Hance were used as materials and planted under 100% full light (FL) and 30% FL (low light, LL) to explore the responses of tree species in different successional stages of subtropical forests to different light environments. Transcriptome sequencing was used to analyze the expression changes in genes related to growth and photoprotection under different light environments. The young leaves of S. superba accumulated more malondialdehyde (MDA) and superoxide radicals (${\mathrm{O}}_2^{{{}^{\bullet}}^{-}}$) under LL. A lower hormone content (auxin, cytokinin, gibberellin) in the young leaves, a weaker photosynthetic capacity in the mature leaves and significant downregulation of related gene expression were also found under LL, which resulted in the total biomass of S. superba under LL being lower than that under FL. The young leaves of C. concinna had less MDA and ${\mathrm{O}}_2^{{{}^{\bullet}}^{-}}$, and a higher hormone contents under LL than those under FL. There was no significant difference in photosynthetic capacity between mature leaves in contrasting light environments. Although the biomass of C. concinna under LL was less than that under FL, the height of C. concinna under LL was higher than that under FL, indicating that C. concinna could grow well under the two light environments. Our results describing the acclimatization of light at the physiological, molecular and transcriptome levels are important for a complete understanding of successional mechanisms.
Asunto(s)
Árboles , Clima Tropical , Bosques , Fotosíntesis , Hojas de la Planta , Transcriptoma , Árboles/genéticaRESUMEN
Ten anthocyanin components have been detected in roots of purple sweet potato (Ipomoea batatas Lam.) by high-performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry. All the anthocyanins were exclusively cyanidins or peonidin 3-sophoroside-5-glucosides and their acylated derivatives. The total anthocyanin content in purple sweet potato powder obtained by solid-phase extraction was 66 mg g(-1). A strong capacity of purple sweet potato anthocyanins (PSPA) to scavenge reactive oxygen species (superoxide, hydroxyl radical) and the stable 1,1-diphenyl-2-picrylhydrazyl organic free radical was found in vitro using the electron spin resonance technique. To determine the functional roles of anthocyanins in leaves in vivo, for the first time, supplemental anthocyanins were infiltrated into leaves of Arabidopsis thaliana double mutant of the ecotype Landsberg erecta (tt3tt4) deficient in anthocyanin biosynthesis. Chlorophyll fluorescence imaging showed that anthocyanins significantly ameliorated the inactivation of photosystems II during prolonged high-light (1300 micromol m(-2) s(-1)) exposure. Comet assay of DNA revealed an obvious role of supplemental PSPA in alleviating DNA damage by high light in leaves. Our results suggest that anthocyanins could function in vitro and in vivo to alleviate the direct or indirect oxidative damage of the photosynthetic apparatus and DNA in plants caused by high-light stress.
Asunto(s)
Antocianinas/química , Arabidopsis/efectos de la radiación , Luz , Hojas de la Planta/efectos de la radiación , Antocianinas/aislamiento & purificación , Arabidopsis/metabolismo , Clorofila/metabolismo , Daño del ADN , ADN de Plantas/efectos de la radiación , Depuradores de Radicales Libres/química , Ipomoea batatas/química , Estrés Oxidativo , Complejo de Proteína del Fotosistema II/efectos de la radiación , Hojas de la Planta/metabolismoRESUMEN
Alocasia macrorrhiza is a fast growing and propagating herbaceous species commonly found in South China. To determine its physiological responses to Pb and Cd stresses, the biochemical, histochemical and cytochemical changes under PbAC2 and CdCl2 phytotoxicity were detected using leaf discs as an experimental model. After leaf discs were infiltrated in different concentrations of PbAC2 and CdCl2 solutions (0, 50, 100, 150, 200 microM) for 72 h, the formation of reactive oxygen species (H2O2 and O2-) in plant tissue were found to be exaggerated together with elevated OH concentration and cell death. Changes in chlorophyll fluorescence (Fv/Fm, PhiPSII, qP and NPQ) imaging colours/areas of leaf discs indicated decreased photosystem II functions by both heavy metal treatments and positive reactions of antioxidants under Pb2+ stress. Results showed that fluorescent detection of hydroxylated terephthlate using terephthalic acid as OH trap is a simple, yet valuable and specific method for monitoring OH generation in plant tissue under heavy metal stresses. As compared with Cd2+, Pb2+ was found to be less toxic, indicating that A. macrorrhiza tissue might have a potential tolerance to Pb.
Asunto(s)
Alocasia/efectos de los fármacos , Cadmio/toxicidad , Contaminantes Ambientales/toxicidad , Plomo/toxicidad , Hojas de la Planta/efectos de los fármacos , Alocasia/crecimiento & desarrollo , Alocasia/metabolismo , Clorofila/metabolismo , Relación Dosis-Respuesta a Droga , Fluorometría , Estrés Oxidativo/efectos de los fármacos , Fotosíntesis/efectos de los fármacos , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Pruebas de ToxicidadRESUMEN
The phosphate-solubilizing medium plate screening and heavy metal resistance rescreening were used to isolate a phosphate-solubilizing bacterium (coded ZLT11) from the rhizosphere of Mikania micrantha. Results from 16S rRNA gene sequence analysis revealed that the strain ZLT11 belonged to Paenibacillus sp. The amount of phosphorus solubilized from calcium phytate and phytic acid by the ZLT11 was 84.10 and 73.84 mg·L-1, respectively. The maximum phosphate solubilizing activity to calcium phytate (95.66 mg·L-1) was at 30 â and initial pH 9.0. The strain ZLT11 displayed the tolerance to ≤ 400 mg·L-1 Pb 2+, ≤ 100 mg·L-1 Cd 2+, and ≤ 40 mg·L-1 Hg 2+. With calcium phytate as phosphorus source, the inoculation strain ZLT11 treatment increased the average root length, root number, seedling height and total biomass of rice seedlings by 106.7%, 76.6%, 49.0% and 46.3%, respectively. The strain ZLT11 could improve rice seedlings growth under Cd stress.
Asunto(s)
Oryza , Paenibacillus , Fosfatos , Ácido Fítico , ARN Ribosómico 16S , Rizosfera , Microbiología del SueloRESUMEN
Sphagneticola trilobata (L.) Pruski is one of the fast-growing malignant weeds in South China. It has severely influenced local biodiversity and native plant habitat. Photosynthesis is the material basis of plant growth and development. However, there are few reports on the photosynthetic transcriptome of S. trilobata. In this study, S. trilobata had a relatively large leaf area and biomass. The gas exchange parameters per unit area of leaves, including net photosynthetic capacity (Pn), intercellular CO2 (Ci), stomatal conductance (Gs), transpiration rate (Tr), water use efficiency (WUE), photosynthetic pigment and Rubisco protein content were higher than those of the native plant Sphagneticola calendulacea (L.) Pruski. On this basis, the differences in photosynthesis pathways between the two Sphagneticola species were analyzed by using the Illumina HiSeq platform. The sequencing results for S. trilobata and S. calendulacea revealed 159,366 and 177,069 unigenes, respectively. Functional annotation revealed 119,350 and 150,846 non-redundant protein database annotations (Nr), 96,637 and 115,711 Swiss-Prot annotations, 49,159 and 60,116 Kyoto Encyclopedia of Genes and Genomes annotations (KEGG), and 83,712 and 97,957 Gene Ontology annotations (GO) in S. trilobata and S. calendulacea, respectively. Additionally, our analysis showed that the expression of key protease genes involved in the photosynthesis pathway, particularly CP43, CP47, PsbA and PetC, had high expression levels in leaves of S. trilobata in comparison to native species. Physiological and transcriptomic analyses suggest the high expression of photosynthetic genes ensures the high photosynthetic capacity of leaves, which is one of the inherent advantages underlying the successful invasion by S. trilobata.
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Péptido Hidrolasas/genética , Fotosíntesis/genética , Proteínas de Plantas/genética , Wedelia/fisiología , Biodiversidad , China , Ecología , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Secuenciación de Nucleótidos de Alto Rendimiento , Anotación de Secuencia Molecular , Hojas de la Planta , Especificidad de la Especie , TranscriptomaRESUMEN
The effects of long-term (33 months) sun/shade acclimation and short-term (within 10 h) HSO(3) (-) treatment on leaf photosynthetic apparatus were investigated in three subtropical forest plants, Pinus massoniana, Schima superba, and Acmena acuminatissima. After 33 months' growth in two light environments (100 and 12% sunlight), rapid light curves (RLC), chlorophyll fluorescence imaging and chloroplast ultrastructures of three tested species were changed to different degrees. When leaf sections were immersed in 50 mM NaHSO(3) for 10 h, all the RLCs were lowered; chlorophyll fluorescence imaging was inclined to present warmer colors and imaging areas were decreased. However, changes in chloroplast ultrastructures differed from three species. Our results showed that the photosynthetic apparatus of a dominant species, A. acuminatissima, in the late succession stage of a subtropical forest in South China, was less sensitive to NaHSO(3) under both growing light intensities. Conversely, the chloroplasts of P. massoniana, the pioneer heliophyte species, were most susceptible to NaHSO(3). It is deduced that, SO(2) pollution may become as a factor to accelerate the succession of subtropical forest.
Asunto(s)
Adaptación Fisiológica/fisiología , Proteínas del Complejo del Centro de Reacción Fotosintética/efectos de los fármacos , Sulfitos/toxicidad , Clorofila/metabolismo , Cloroplastos/efectos de los fármacos , Cloroplastos/metabolismo , Cloroplastos/ultraestructura , Hojas de la Planta/efectos de los fármacos , Especificidad de la Especie , Luz SolarRESUMEN
Light attenuation and antioxidation are the main mechanisms of photoprotection by anthocyanin under high light (HL) stress. Anthocyanin synthase (ANS) is the key enzyme in the downstream portion of anthocyanin synthetic pathways. To explore the role of ANS in photoprotection by anthocyanin under HL stress, homozygous ANS-deficient Arabidopsis mutants were screened from SALK_073183 and SALK_028793. Here, we obtained two deficient mutants, ans-1 and ans-2, which had ANS gene expression levels equal to 5.9 and 32.9% of that of Col respectively. By analysing their physiological and biochemical responses to HL stress, we found that there were positive correlations among ANS expression level, anthocyanin content and resistance to HL. The line with the lowest ANS expression level, ans-1, was also the most sensitive to HL, showing the lowest anthocyanin content, chlorophyll content, Fv/Fm ratio, and Rubisco content and the highest O2â¢- accumulation and membrane leakage rate, although it also had the highest antioxidant capacity. Experimental evidence suggests that ANS mainly regulated the light-attenuating function of anthocyanin in photoprotection under HL. Blocking excess light is an important function of anthocyanin that protects plants from HL stress, and a high antioxidant capacity cannot compensate for the absence of the light-shielding function of anthocyanin.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Antocianinas , Etiolado , LuzRESUMEN
The leaves of many plants are red during particular stages of their lives, but the adaptive significance of leaf colouration is not yet clearly understood. In order to reveal whether anthocyanins play a similar role (i.e. antioxidants) in different seasonal contexts, this study investigated species with red young leaves in the subtropical forest of Dinghushan biosphere reserve (South China) during summer and winter and compared group leaf characteristics between the two seasons. Of 62 total species, 33 exhibited red young leaves in summer only, 6 in winter only, and 23 in both seasons. The anthocyanins extracted from most of these species had an absorption peak at ~530 nm. Frequency distribution analysis showed that the species containing anthocyanins at levels ranging from 0.02 to 0.04 µmol cm-2 occurred most frequently in summer or winter. Based on conditional grouping of the species, no significant variation was observed in the average anthocyanin contents and antioxidant abilities between summer and winter; the flavonoid content in summer was 2-fold that in winter, whereas the anthocyanin:flavonoid ratio in summer was only half that in winter. Moreover, a positive correlation between anthocyanins and flavonoids was found in summer. Therefore, it is less likely for anthocyanins to serve as antioxidants in summer than winter, because such a function in summer leaves is readily replaced by other flavonoids.