Active Reaction Centers Research Articles

The Effect of Carbon-Based Substrates onto Non-Precious and Precious Electrocatalytic Centers

Here, we report the effect of substrate for tuning the active reaction center of precious and non-precious electrocalysts for efficient oxygen reduction reaction (ORR) activity. We have selected surface modified carbon morphologies to study the substrate effect on Pt and CoSe2 catalytic center. Pt supported on surface modified carbon nanotube (CNT) substrates shows, defective sites is important for effective dispersion of Pt on it. CO stripping process probes the effect of Pt interaction with defective and graphitic domains of carbon support. Improved mass activity and specific activity is observed for Pt supported on pyridine functionalized CNT compared to Pt on other CNT substrate. Similarly, CoSe2 supported on nitrogen doped carbon nanohorn (NCNH) shows improved ORR activity in alkaline and acid conditions compared to other carbon based substrates. Enhanced mass activity and specific activity of CoSe2/NCNH is observed in both alkaline and acidic media compared to CoSe2 supported on other modified substrates.

Phytoplasmas change the source–sink relationship of field-grown sweet cherry by disturbing leaf function

Changes in the function of field-grown sweet cherry leaves infected with phytoplasma were evaluated through the analysis of photosynthesis, respiration, carbohydrates and hormones. Phytoplasmal infection caused witches' broom, small leaves, leaf yellowing and leaf rolling. The photosynthesis of infected leaves was considerably reduced, and they were unable to produce sufficient carbohydrates for their own needs. In contrast, the starch content of infected leaves was significantly increased. These results demonstrate the change in the role of infected leaves from sources to sinks. Further analysis revealed that the photosynthetic decline was related to a significant decrease in photosynthetic pigments and to marked inactivation of photosystem II (PSII). Furthermore, the loss of PSII function was due to a decrease in chlorophyll content, reduction and closure of active reaction centers, and decline in photochemical efficiency.

Increased grain yield with improved photosynthetic characters in modern maize parental lines

The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation technology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are crucial for innovating new germplasm. Here, we analyzed variations in grain yield and a series of eco-physiological photosynthetic traits after anthesis in sixteen parental lines of maize (Zea mays L.) released during three different eras (1960s, 1980s, 2000s). We found that grain yield and biomass significantly increased in the 2000s than those in the 1980s and 1960s. Leaf area, chlorophyll, and soluble protein content slowly decreased, and maintained a higher net photosynthesis rate (Pn) and improved stomatal conductance (Gs) after anthesis in the 2000s. In addition, the parental lines in the 2000s obtained higher actual photochemistry efficiency (ΦPSII) and the maximum PSII photochemistry efficiency (Fv/Fm), which largely improved light partitioning and chlorophyll fluorescence characteristic, including higher photochemical and photosystem II (PSII) reaction center activity, lower thermal energy dissipation in antenna proteins. Meanwhile, more lamellae per granum within chloroplasts were observed in the parental lines of the 2000s, with a clear and complete chloroplast membrane, which will greatly help to improve photosynthetic capacity and energy efficiency of ear leaf in maize parental lines. It is concluded that grain yield increase in modern maize parental lines is mainly attributed to the improved chloroplast structure and more light energy catched for the photochemical reaction, thus having a better stay-green characteristic and stronger photosynthetic capacity after anthesis. Our direct physiological evaluation of these inbred lines provides important information for the further development of promising maize cultivars.

Imaging of fast chlorophyll fluorescence induction curve (OJIP) parameters, applied in a screening study with wild barley (Hordeum spontaneum) genotypes under heat stress

We quantified the influence of heat stress (HS) on PSII by imaging of parameters of the fast chlorophyll fluorescence (CF) induction (OJIP) kinetic of 20 genotypes of wild barley (Hordeum spontaneum) covering a broad geographical spectrum. We developed a standardised screening procedure, allowing a repetitive fluorescence measurement of leaf segments. The impact of HS was quantified by calculating a Heat Resistance Index (HRI), derived from the decrease of the Performance Index (PI) caused by HS treatment and following recovery. For the genotype showing the lowest HRI, reduced maximum quantum yield (φP0) and increased relative variable fluorescence of the O-J phase (K-Peak) were detected after HS, whereas the basal fluorescence (F0) remained stable. An additional feature was a lowered fraction of active (QA-reducing) reaction centres (RCs). The disturbances disappeared after one day of recovery. Spatial heterogeneities of fluorescence parameters were detected, as the negative effect of HS was stronger in the leaf areas close to the leaf tip. The results of this study prove that chlorophyll fluorescence imaging (CFI) is suitable for the detection of HS symptoms and that imaging of JIP-Test parameters should be considered in future screening and phenotyping studies aiming for the characterisation of plant genotypes.

The Effect of Carbon-Based Substrates onto Non-Precious and Precious Electrocatalytic Centers

Novel catalysts based on precious and non-precious catalytic centers, as well as support materials are currently under investigation all over the world. The improvement of oxygen reduction reaction (ORR) on Pt-based catalysts is strongly related to its dispersion and interaction with the substrates. [1],[2] The tolerance to small organics is also influenced by the electronic modification of the catalytic center itself or induced by the substrate.[3] A variety of carbon-based substrates such as carbon nanotubes (CNT), graphite (HOPG), graphene, carbon nanohorns (CNH),[4] various graphitic domains of MWCNT, and non-carbonaceous based materials, such as metal oxides (Titania, doped-Titania, Yttria, Ceria, etc.) [5],[6]can be used as both catalyst and catalyst support materials. On the way to further explore the substrate effect on non-precious electrocatalyst, CoSe2was supported on Carbon, CNH and nitrogen doped nanohorn (NCNH). The activity of non-Pt catalysts was found to be strongly dependent on the surface composition of substrate materials. The improved interaction of modified substrate and the metal centers (either precious or non-precious) modify the active reaction centers of the electrocatalyst, which in turn boost the catalytic activity towards molecular oxygen reduction with minimum overpotential. The analysis indicates that the improved activity measured in half-cells was validated in microfluidic fuel cells. Acknowledgements Authors acknowledge the partial support of the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Fuel Cell and Hydrogen Joint Technology Initiative under grant agreement nr 303492 CathCat. SM U acknowledges Raman-Charpak fellowship, JMMH, J.M.M.-H., C.A. C.-R., and L.A. E-W acknowledge financial support from CONACYT-Mexico Nr.: MX-351743; MX-561206; MX-234729. [1] Y. Luo, N. Alonso-Vante, Electrochim. Acta, doi: 10.1016/j.electacta.2015.04.098. [2] J. Ma, A. Habrioux, Yun Luo, G. Ramos-Sanchez, L. Calvillo, G. Granozzi, P. B. Balbuena, N. Alonso-Vante, J Mater. Chem. A, Submitted; J. Ma, A. S. Gago, W. Vogel, N. Alonso-Vante, Chemcatchem, 2013, 5, 701-705. [3] J. Ma, A.S. Gago, W. Vogel, N. Alonso-Vante, Tailoring and Tuning the Tolerance of a Pt Chalcogenide Cathode Electrocatalyst to Methanol, ChemCatChem, 5 (2013) 701-705. [4] Sreekuttan M. Unni, J. M. Mora-Hernandez, Sreekumar K., N. Alonso-Vante, ChemElectroChem, Submitted. [5] C.Liu , Y.Wei and K.Wang, Chem.Comm., 2010, 46, 2483-2485. [6] Y. Luo, A. Habrioux, L. Calvillo, G. Granozzi, N. Alonso-Vante, ChemCatChem, doi: 10.1002/cctc.201500130.

A geminivirus betasatellite damages the structural and functional integrity of chloroplasts leading to symptom formation and inhibition of photosynthesis.

Geminivirus infection often causes severe vein clearing symptoms in hosts. Recently a betasatellite has emerged as a key regulator of symptom induction. To understand the host-betasatellite interactions in the process of symptom development, a systematic study was carried out involving symptoms induced by a betasatellite associated with radish leaf curl disease (RaLCB) in Nicotiana benthamiana. It has been found that βC1 protein localized to chloroplasts of host cells, and RaLCB lacking βC1, which failed to produce symptoms, had no effect on chloroplast ultrastructure. Vein flecking induced by transiently expressed βC1 was associated with chloroplast ultrastructure. In addition, the betasatellite down-regulates expression of genes involved in chlorophyll biosynthesis as well as genes involved in chloroplast development and plastid translocation. Interestingly, the expression of key host genes involved in chlorophyll degradation remains unaffected. Betasatellite infection drastically reduced the numbers of active reaction centres and the plastoquinol pool size in leaves exhibiting vein clearing symptoms. Betasatellite-mediated impediments at different stages of chloroplast functionality affect the photosynthetic efficiency of N. benthamiana. To the best of the authors' knowledge, this is the first evidence of a chloroplast-targeting protein encoded by a DNA virus which induces vein clearing and structurally and functionally damages chloroplasts in plants.

Kaolin-based, foliar reflective film protects photosystem II structure and function in grapevine leaves exposed to heat and high solar radiation

Extreme conditions, such as drought, high temperature, and solar irradiance intensity, are major factors limiting growth and productivity of grapevines. In a field experiment, kaolin particle film application on grapevine leaves was examined during two different summer conditions (in 2012 and 2013) with the aim to evaluate benefits of this practice against stressful conditions hindering photochemical processes. We used chlorophyll a fluorescence to investigate attached leaves. Two months after the application, during the hottest midday, the kaolin-treated plants showed by the JIP test significantly higher quantum yield of PSII photochemistry, flux ratios, maximum trapped excitation flux of PSI, absorption flux, electron transport flux, maximum trapped energy flux per cross section, and performance index than plants under control conditions in the warmer year. On the contrary, the treated plants showed a lower initial slope of relative variable fluorescence and a decrease in the absorption and electron transport per cross section. The JIP test showed higher efficiency of PSII in the plants treated with kaolin mainly in 2013 (higher temperature and drought). Our results supported the hypothesis that the accumulation of active PSII reaction centres was associated with decreased susceptibility to photoinhibition in the kaolin-treated plants and with more efficient photochemical quenching. Grapevines in the Douro Region seems to profit from the kaolin application.

CoSe2 Supported on Nitrogen‐Doped Carbon Nanohorns as a Methanol‐Tolerant Cathode for Air‐Breathing Microlaminar Flow Fuel Cells

AbstractThe synthesis of CoSe2 nanoparticles supported on nitrogen‐doped carbon nanohorns (CoSe2/NCNH) and the influence of the interaction of the metal centre with the NCNH on the oxygen reduction reaction (ORR) are reported. CoSe2/NCNH shows a 50 mV lower onset overpotential and a 150 mV positive shift in the half‐wave potential compared to CoSe2 supported on carbon and carbon nanohorns. This suggests that the intrinsic activity and the density of active reaction centres of CoSe2 are modified by NCNHs. An air‐breathing direct methanol microlaminar flow fuel cell (μLFFC) is constructed using CoSe2/NCNH as a methanol‐tolerant cathode catalyst. A maximum power density of 10.05 mW cm−2 and a maximum current density of 124.20 mA cm−2 are achieved with CoSe2/NCNH compared to the non‐doped catalyst, CoSe2/C and Pt/C with 5 M methanol as the fuel. The improved activity of CoSe2/NCNH is attributed to the peculiar morphology and the nitrogen doping of the carbon nanohorns. This catalyst could be a suitable alternative to Pt.

Physiological and photosynthetic response of quinoa to drought stress

Water shortage is a critical problem touching plant growth and yield in semi-arid areas, for instance the Mediterranean region. For this reason was studied the physiological basis of drought tolerance of a new, drought tolerant crop quinoa (Chenopodium quinoa Willd.) tested in Morocco in two successive seasons, subject to four irrigation treatments (100, 50, and 33%ETc, and rainfed). The chlorophyll a fluorescence transients were analyzed by the JIP-test to transiate stress-induced damage in these transients to changes in biophysical parameter's allowing quantification of the energy flow through the photosynthetic apparatus. Drought stress induced a significant decrease in the maximum quantum yield of primary photochemistry (Φpo = Fv/Fm), and the quantum yield of electron transport (Φeo). The amount of active Photosystem II (PSII) reaction centers (RC) per excited cross section (RC/CS) also decreased when exposed to the highest drought stress. The effective antenna size of active RCs (ABS/RC) increased and the effective dissipation per active reaction centers (DIo/RC) increased by increasing drought stress during the growth season in comparison to the control. However the performance index (PI), was a very sensitive indicator of the physiological status of plants. Leaf area index, leaf water potential and stomatal conductance decreased as the drought increased. These results indicate that, in quinoa leaf, JIP-test can be used as a sensitive method for measuring drought stress effects.

Effect of dehydration on spectral reflectance and photosynthetic efficiency in Umbilicaria arctica and U. hyperborea

In many polar and alpine ecosystems, lichens of genus Umbilicaria represent dominant species forming community structure. Photosynthetic and spectral properties of the lichens may change rapidly according to an actual hydration status of their thalli. In this study, we investigated responses of photochemical reflectance index (PRI), normalized difference vegetation index (NDVI), effective quantum yield of photosynthetic efficiency of photosystem (PS) II (ΦPSII), and several photosynthetic parameters derived from fast induction kinetics of chlorophyll fluorescence (OJIP) to controlled dehydration. We used U. arctica and U. hyperborea collected close to Nuuk, Greenland. In both the species, PRI showed a curvilinear increase with dehydration, i.e., a decreasing water potential (Ψw). The increase was apparent within Ψw range of 0 to -10 MPa. The PRI increase was less pronounced in U. arctica than in U. hyperborea. NDVI decreased with a progressive thallus dehydration in both the species, however, throughout Ψw range of 0 to -30 MPa, U. hyperborea had lower NDVI values than U. arctica. The relationship between ΦPSII and Ψw resulted in a typical S curve. A critical Ψw at which photosynthetic processes were fully inhibited was -30 MPa in both the species, however, species-specific differences in the S curve shape were found. Analyses of photosynthetic parameters derived from OJIPs revealed that the absorption of radiation energy and a trapping rate increased with dehydration in active reaction centres of PS II, the number of which decreased with a more pronounced lichen thallus dehydration. It is concluded that U. arctica and U. hyperborea possess effective physiological mechanisms to maintain an effective photosynthesis when partly dehydrated (the Ψw range of 0 to -15 MPa). In spite of similar ecological niches that these two lichens occupy in nature, their spectral and photosynthetic properties differred.

In vivo evaluation of the high-irradiance effects on PSII activity in photosynthetic stems of Hexinia polydichotoma

Green photosynthetic stems are often responsible for photosynthesis due to the reduction of leaves in arid and hot climates. We studied the response of PSII activity to high irradiance in the photosynthetic stems of Hexinia polydichotoma in the Taklimakan Desert by analysis of the fast fluorescence transients (OJIP). Leaf clips of a chlorophyll fluorometer were used in conjunction with a sponge with a 4-mm-width groove to prevent light leakage for precise in vivo measurements. High irradiance reduced performance indices, illustrating the photoinhibition of PSII to some extent. However, the decrease in active reaction centers (RC) per PSII absorption area and maximum quantum yield indicated a partial inactivation of RCs and an increase in excitation energy dissipation, resulting in downregulation of photosynthetic excitation pressure. In addition, the increased efficiency of electron transport to PSI acceptors alleviated overexcitation energy pressure on PSII. These mechanisms protected the PSII apparatus as well as PSI against damages from excessive excitation energy. We suggested that H. polydichotoma exhibited rather photoadaptation than photodamage when exposed to high irradiance during the summer in the Taklimakan Desert. The experiment also demonstrated that the modified leaf clip can be used for studying dark adaptation in a photosynthetic stem.

Characteristics of Coke Deposition Over a SAPO-34 Catalyst in the Methanol-to-Olefins Reaction

The deactivation of SAPO-34 catalyst in the methanol-to-olefins process has been studied at temperatures of 400 to 475°C. The catalyst activity keeps stable before a rapid deactivation occurs at a critical coke content. The analysis of retained coke species showed that methylbenzenes were the most abundant species at lower temperatures (400°C and 425°C), while polycyclic aromatics became the dominant species at 475°C. The growth in the retained coke species with increasing temperature comes from the enhanced reactivity of methylbenzenes and methylnaphthalenes at high reaction temperature, where methylnaphthalenes may function as another active reaction centers.

옥수수의 파종시기 및 질소수준별 광화학적 반응 해석

본 연구는 파종시기와 질소시비 수준에 대한 옥수수의 광화학적 반응을 분석하여 광생리적 특성을 해석하였다. 1. 5월 22일 파종시 질소 함량이 증가함에 따라 생육후기까지 엽록소 형광량 또한 증가하여 질소 배량처리에서 광이용효율이 더 높은 것으로 확인되었다. 2. 생육초기의 형광량이 가장 높았으며, 이후 모든 처리구에서 엽록소 형광량이 50% 가량 감소하여 전자전달을 위한 광화학 반응이 크게 감소했음을 알 수 있었다. 3. 질소 반량구에서 활성화된 RC (RC/ABS)가 감소하며 13% 이상의 에너지가 손실되었으며, 결국 전자전달시 에너지 전환효율(PI, DF 등)이 감소해 광이용효율이 낮았다. 4. 배량 처리구는 생육후기로 갈수록 전자전달 효율(ET2o/CS) 및 단면당 활성화된 RC(RC/CS) 등 광이용 효율이 대조구 대비 크게 증가하여 광합성기구 사이의 전자전달이 잘 이루어지는 것으로 확인되었다. The photochemical characteristics were analyzed in the context of sowing time and different levels of fertilized nitrogen during the maize (Zea mays L.) growth. When maize was early sawn, the fluorescence parameters related with electron-transport, in photosystem II (PSII) and PSI, were effectively enhanced with the higher level of fertilized nitrogen. Highest values were observed in maize leaves grown in double N-fertilized plot. The photochemical parameters were declined in the progress of growth stage. In early growth stage, the fluorescence parameters were highest, and then reduced to about half of the parameters related with electron transport on PSII and PSI at middle and late growth stages. In 1/2 N plot, the photochemical energy dissipation was measured to 13% in term of active reaction center per absorbed photon resulting in decrease in performance index and driving force of electron. This decrease induced to lower the photochemical effectiveness. In 2 N plots, the electron transport flux from <TEX>$Q_A$</TEX> to <TEX>$Q_B$</TEX> per cross section and the number of active PSII RCs per cross section were considerably enhanced. It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective.

Growth Improvement of Nicotiana and Arabidopsis In Vitro by Microalgal Conditioned Media

Abstract Conditioned medium (CM) is a general term describing media in which cells have already been cultivated for some time. Such media, usually clarified by filtration, have been used by plant biotechnologists as additives sup-porting the growth of cell suspensions, organs and whole plants. This study examined the effect of CM obtained from green alga Desmodesmus subspicatus on the growth and functioning of the photosynthetic apparatus of Nicotiana tabacum and Arabidopsis thaliana in culture in vitro. Plants where cultured on CM diluted 1.25-, 2-and 5-fold with MS medium. The increase in fresh and dry weight was highest in tobacco and Arabidopsis cultured on CM/2 and CM/1.25 media. Those two concentrations also increased the amount of chlorophylls in both plants tested. CM improved parameter PI (reflecting the photosynthetic “vitality” of the organism) and electron transport efficiency, and increased the fraction of active reaction centers. Analysis of chlorophyll fluorescence in vivo suggests that the improvement of these plants grown in the presence of algal CM may result from stimulation of photosynthesis. Algal CM offers a convenient, cheap, universal supplement for stimulating the growth of higher plants in vitro.

Substrate Effects on the Catalytic Center of CoSe2 for Oxygen Reduction Reaction

Here, we report the tuning of active reaction center of the CoSe2 nanoparticles by nitrogen doped carbon nanohorns (NCNH). CoSe2 nanoparticles supported on NCNH (CoSe2/NCNH) shows improved oxygen reduction reaction (ORR) activity compared to the same supported on carbon nanohorns and Vulcan carbon. An improved positive shift in onset potential (50 mV) and half-wave potential (150 mV) of CoSe2/NCNH compared to other catalysts indicates the intrinsic activity as well as active reaction center of CoSe2 modulated by the presence of NCNH. CoSe2/NCNH reduces molecular oxygen to hydroxide through a four-electron transfer pathway with improved electrochemical stability in alkaline condition. Air breathing direct methanol micro laminar flow fuel cells (DM-µLFFC) performance of CoSe2/NCNH as cathode catalyst shows a maximum power density and current density respectively of 10.05 mW cm-2 and 124.20 mA cm-2 with 5M methanol as fuel.

Quantitative trait locus mapping of chlorophyll a fluorescence parameters using a recombinant inbred line population in maize

Chlorophyll a fluorescence parameters, derived from its induction, known as the OJIP rise, are often used to characterize the structure and function of photosystem II (PSII). Under field conditions, structure and function of photosystems of crops can be affected by various environmental factors. This study was conducted to identify quantitative trait loci (QTLs) associated with chlorophyll fluorescence parameters in field-grown maize. During three growing seasons, a recombinant inbred line population, consisting of 228 lines, was evaluated for five chlorophyll fluorescence parameters, which indirectly measure: absorbed photon flux per cross section of leaf (ABS/CSo), maximum trapped exciton flux per cross section of leaf (TRo/CSo), electron transport flux from QA to QB per cross section of leaf (ETo/CSo), number of active PSII reaction centers (RCs) per cross section of leaf (RC/CSo), and the performance index on a cross section of leaf (PICS). Significant correlations were frequently observed among these chlorophyll fluorescence parameters. Three major genomic regions dispersed across chromosomes 1, 5, and 9 were detected to be associated with chlorophyll fluorescence parameters. The genomic region in chromosome bins 9.06–9.07 contained QTLs that not only showed pleiotropy for multiple chlorophyll fluorescence parameters but also showed stable expression and explained a large proportion of the phenotypic variation. Additionally, a QTL for grain yield was also detected in this important genomic region. The identified QTLs for chlorophyll fluorescence parameters in the present study may help elucidate plants’ responses to environmental cues and assist in developing marker-assisted selection breeding programs in maize.

Assessment of phytotoxicity of anthracene in soybean (Glycine max) with a quick method of chlorophyll fluorescence.

A decrease in photosynthetic efficiency may indicate the toxic effects of environmental pollutants on higher plants. Measurement of chlorophyll (Chl) a fluorescence to assess the performance of photosystem II (PSII) was used as an bioindicator of toxicity of the polycyclic aromatic hydrocarbon (PAH) anthracene (ANT) in soybean plants. The results revealed that ANT treatment caused a reduction in quantum yield of PSII, damage to the oxygen evolving complex, as well as a significant reduction in performance index of PSII. However, change in performance index was more prominent, and it seems that the performance index is a more sensitive parameter to environmental contaminants. Moreover, a change in heterogeneity of PSII was also observed. The number of active reaction centres decreased with increasing concentration of ANT, as secondary plastoquinone reducing centres were converted into non-reducing centres, and PSIIα centres were converted into PSIIβ and PSIIγ centres. The influence of ANT on PSII heterogeneity could be an important reason for reductions in the PSII performance.

Photosynthetic acclimation of sweet sorghum under progressive water stress

This study addressed photosynthetic acclimation of sweet sorghum under progressive soil drying at different growth stages: (i) three fully expanded leaves (D1); (ii) growing point differentiation (D2); (iii) booting (D3); (iv) half-blooming (D4). Soil water potential (SWP), photosynthetic traits and soluble sugars accumulation were determined. Under progressive drought stress, D1 and D2 photosynthesized until 20 days after stress imposition (SWP≈−3.5MPa), while, D3 and D4 were phothosynthetically inactive 12 days after irrigation suspension (SWP≈−1.5MPa). Photoprotection mechanisms also changed with plant age: in mature plants, electron transport rate per cross section (ETo/CSm), and silent PSII reaction centers (RCs) drastically declined at SWP of −1.0MPa, while remained unchanged in young plants until −1.5MPa. As water stress increased (SWP<−1.8MPa), the light energy absorption (ABS/CSm), the trap energy flux (TRo/CSm) and ETo/CSm dramatically decreased in mature plants (−70% compared to control). Soluble sugars significantly correlated with thermal energy dissipation (DIo/CSm) and density of active reaction centers (RCo/CSm) at young stages. The acceptor side of Photosystem I (PSI) was affected by plant age resulting in a lower efficiency than donor side of PSII.

模拟岩溶旱钙土壤基质中AM真菌对玉米幼苗光合生长的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟岩溶旱钙土壤基质中AM真菌对玉米幼苗光合生长的影响 DOI: 10.5846/stxb201402190287 作者: 作者单位: 西南大学生命科学学院,西南大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31360106) Effect of AMF on the photosynthetic characteristics and growth of maize seedlings under the stress of drought, high calcium and their combination in Karst area Author: Affiliation: School of Life Science,Southwest University,School of Life Science,Southwest University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:利用盆栽试验,探讨了AM真菌在模拟岩溶区干旱、高钙及其双重胁迫的土壤基质中对玉米幼苗光合生长的影响。结果表明:玉米幼苗的菌根侵染率在不同处理下的大小顺序为对照 > 干旱 > 双重胁迫 > 高钙。无论接种与否,干旱、高钙及其双重胁迫均导致玉米幼苗生物量、净光合速率下降。未接种AM真菌条件下,玉米幼苗生物量在干旱、高钙及其双重胁迫下较对照分别低3.2%、63.7%、76.0%,净光合速率较对照分别低33.4%、86.9%、98.8%;接种AM真菌条件下,玉米幼苗生物量在干旱、高钙及其双重胁迫下较对照分别低16.3%、78.4%、80.2%,净光合速率较对照分别低9.7%、92.8%、91.7%。与同种条件下的非菌根植株相比,干旱及双重胁迫下的菌根植株生物量、叶绿素含量、光合蒸腾速率、最大光化学效率,以及P吸收均呈上升趋势;高钙胁迫下的菌根植株叶绿素含量、最大光化学效率有所增加,但生物量、光合蒸腾速率以及N、P的吸收未体现菌根促进效应。AM真菌与干旱及双重胁迫的交互作用对玉米幼苗的净光合速率影响显著,与高钙交互作用对玉米幼苗净光合速率无显著影响。AM真菌能够通过促进玉米幼苗N、P吸收及叶绿素含量增加,光化学效率、气孔导度增大,从而提高玉米幼苗光合作用能力促进生长。实验结果对岩溶生态系统中合理利用菌根技术及制定合理的农业生产措施具有重要的理论和实践意义。 Abstract:Drought and high concentration of calcium are the main characters of the karst soils, and always show great heterogeneity in the karst ecosystems. In order to explore the effects of AMF on the photosynthetic and growth characters of maize (Zea mays L.) under various stresses, three treatments including drought, high concentration of calcium (high Ca), and their combination (double stress) were applied to potted maize seedlings. The results showed that the colonization rate of the AMF to maize seedlings was following the sequence of: control > drought > double stress > high Ca. Compared to the control group, the biomass, net photosynthetic rate (Pn) of the seedlings were decreased in the three treatments. Under non-inoculation conditions, the biomass of maize seedlings subjected to drought, high calcium and double stress were 3.2%, 63.7%, 76% lower than that of control respectively, while those of Pn were 33.4%, 86.9%, and 98.8%. In the same time, under inoculation conditions, compared with the control, the seedling's biomass in drought, high calcium and double stress were 16.3%, 78.4%, 80.2% lower, and net photosynthetic rate were 9.7%, 92.8%, and 91.7% lower. Additionally, compared to the seedlings without AMF, those vaccinated AMF showed significantly higher biomass, chlorophyll content, transpiration rate (Tr), maximum photochemical efficiency, and absorbed more phosphorus, when subjected to the drought and double stress. On the contrary, in the environment of high calcium, the AMF only enhanced the content of chlorophyll, maximum photochemical efficiency, while there was no increase in terms of plant biomass, Tr and the absorbing amount of nitrogen and phosphorus. Moreover, the interaction of AMF×drought and AMF×double stress had significant effects on the Pn of seedlings, while no significant effects of AMF×high Ca were found on the Pn. AM fungi can assist the plant to absorb more phosphorus, enhancing the contents of chlorophyll, improving the activity of light reaction center, increasing the plant stomatal conductance, so as to enhance photosynthesis ability to promote the growth of plant. This research can provide references for a reasonable utilization of AMF and increasing agricultural productivity in the karst ecosystem. 参考文献 相似文献 引证文献

Enhanced Yield and Physiological Performance of Mediterranean Grapevines through Foliar Kaolin Spray

Future climate in the Mediterranean grapevine (Vitis vinifera L.) growing regions will be characterized by more severe summer conditions, with lower water availability, increased temperature and elevated solar irradiance, which may bring relevant changes in grapevine performance. Although grapevines have several survival strategies, the amounting evidence for significant climate change in the upcoming decades urges short-term adaptation measures to be taken. With this in mind, the potential protective role of 5% foliar kaolin (KL), a white and inert clay mineral, was examined in the Port Wine Region over a two year period (2012 and 2013). The results revealed that leaves treated with KL showed higher light reflectance, lower leaf temperature and greater water potential, namely at midday period. As a consequence, net photosynthetic rates increased, particularly due to a lowering of mesophyll limitations, which include lesser perturbations in PSII photochemistry processes. In fact, sprayed KL plants had higher accumulation of active PSII reaction centres (RC) and capture efficiency of excitation energy by open RC, maximum and effective quantum efficiency of PSII, and electron transport rate. Moreover, KL application reduces the oxidative damage on cell membranes by lipid peroxidation. Altogether, these results and the delays in leaf senescence of grapevines sprayed with KL inhibited scorching of clusters and, consequently, lead to a higher yield per plant. Thus, kaolin is a very promising and cost- effective compound to alleviate the negative effects of summer stress in Mediterranean grapevines. In addition, since KL is a natural product can be used in organic farming.