Effect of high light and desiccation on photosystem Ⅱ in the seedlings and mature plants of tropical seagrass Enhalus acoroides during low tide

During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The response of leaves of E.acoroides to high light and desiccation was compared for seedlings and mature plants.Results show that the resistance of seedling and mature leaves to high light was quite similar,but to desiccation was very different.Seedling leaves were more sensitive to desiccation than the mature plant leaves,but had better water retention.The damage of desiccation to seedling leaves was mainly caused by dehydration,whereas that to mature plant leaves was caused by hypersaline toxicity.The recovery rate of PSⅡ of seedling leaves was significantly slower than that of the mature plants after the stresses disappeared,which may at least partly contribute to seedling mortality in the wild.In addition,compared to high light,desiccation seriously inhibited the recovery rate of PSⅡ activities even if the leaves became fully rehydrated to their normal relative water content(RWC)in the following re-immersion.Desiccation inhibited the recovery rate of RC/CS_(M)(reaction center per cross section(at t=t_(Fm)))to decrease the production of assimilatory power,which maybe the cause of the slower PSⅡ recovery in desiccation treatments.This study demonstrates that desiccation particularly coupling with high light have a very negative ef fect on the PSⅡ of E.acoroides during low tide and the sensitivity of seedlings and mature plants to desiccation is significantly different,which have important reference significance to choose an appropriate transplanting depth where seedlings and mature plants of E.acoroides not only receive sufficient light for growth,but also that minimize desiccation stress during low tide.

Metabolomics of astaxanthin hyperaccumulation in Haematococcus pluvialis under high light stress

Variation in metabolite profiles of Haematococcus pluvialis(a type of unicellular green algal)under light stress is a key issue of study at the present.To investigate the effect of light intensity on accumulation of astaxanthin in H.pluvialis,a 26-day batch culture experiment of H.pluvialis under the light intensity levels at 73,127,182,236,and 291μmol/(m^(2)·s)was conducted.Therefore,the optimal light intensity and the corresponding metabolic pathways of accumulation in H.pluvialis were determined.Results show that 236μmol/(m^(2)·s)was the optimum light intensity to induce astaxanthin accumulation,at which a maximum content of 9.01 mg/L was achieved on Day 24.A total of 132 metabolites were identified and quantified,of which 38 differential metabolites were highlighted and classified,including 3 fatty acids or intermediates,5 amino acids or derivatives,5 carbohydrates or intermediates,16nucleoside derivatives,and 9 other metabolites using LC-MS/MS technique.Subsequently,16 statistically significant differential metabolic pathways were enriched and annotated based on Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis between the control and the 236μmol/(m^(2)·s)treatment group(P<0.05).In addition,the bioprocesses included cellular basal metabolism and signaling systems,such as carbohydrate metabolism,amino acid metabolism,glycerol and derivatives metabolism,nucleotide and derivative metabolism,and inositol phosphate metabolism were activated and regulated under strong light stress conditions.Moreover,4 hub metabolites containing D-glucose-6-phosphate,L-tyrosine,glycerol-3-phosphate,and L-glutamine were identified,based on which the associated metabolic network was constructed.The study provided a metabolomic view of astaxanthin accumulation in H.pluvialis under strong light stress.

Identification of Green-Revertible Yellow 3(GRY3),encoding a 4-hydroxy-3-methylbut-2-enyl diphosphate reductase involved in chlorophyll synthesis under high temperature and high light in rice

Chlorophyll,a green pigment in photosynthetic organisms,is generated by two distinct biochemical pathways,the tetrapyrrole biosynthetic pathway(TBP) and the methylerythritol 4-phosphate(MEP)pathway.MEP is one of the pathways for isoprenoid synthesis in plants,with 4-hydroxy-3-methylbut-2-enyl diphosphate reductase(HDR) catalyzing its last step.In this study,we isolated a greenrevertible yellow leaf mutant gry3 in rice and cloned the GRY3 gene,which encodes a HDR participating in geranylgeranyl diphosphate(GGPP) biosynthesis in chloroplast.A complementation experiment confirmed that a missense mutation(C to T) in the fourth exon of LOC_Os03g52170 causes the gry3 phenotype.Under high temperature and high light,transcript and protein abundances of GRY3 were reduced in the gry3 mutant.Transcriptional expression of chlorophyll biosynthesis,chloroplast development,and genes involved in photosynthesis were also affected.Excessive reactive oxygen species accumulation,cell death,and photosynthetic proteins degradation were occurred in the mutant.The content of GGPP was reduced in gry3 compared with Nipponbare,resulting in a stoichiometric imbalance of tetrapyrrolic chlorophyll precursors.These results shed light on the response of chloroplast biogenesis and maintenance in plants to high-temperature and high-light stress.

Effects of High Temperature and Strong Light Combine Stress on Yield and Quality of Early Indica Rice with Different Amylose Content during Grout Filling

High temperature(HT)accompanied with strong light(SL)often occurs in early indica rice production during grout filling stage in Southern China,which accelerates grain ripening.Two indica rice cultivars with different amylose content(Zhongjiazao17,ZJZ17,high amylose content;Xiangzaoxian45,XZX45,low amylose content)were grown under control(CK),HT,and HT+SL conditions during grout filling to determine the effects on grain yield and quality of rice.The results showed that compared with CK,HT and HT+SL significantly reduced the 1000-grain weight and filled grain rate whether in high or low amylose content early indica rice cultivars during grout filling,resulting in a significantly lower grain yield.Meanwhile,HT and HT+SL significantly decreased the milled rice rate,brown rice rate and head rice rate,whereas significantly increased chalky rate and chalky degree;and breakdown decreased and setback,pasting temperature increased in the cultivars,leading to the poor processing,appearance and cooking and eating quality of early indica rice cultivars.Compared with HT,the yield of ZJZ17 was significantly decreased under HT+SL,due to the lower 1000-grain weight.However,the effect of HT+SL on rice quality varied in the cultivars.In general,the yield and rice quality of ZJZ17 were relatively poor under HT+SL.Our results suggested that HT and HT+SL during grout filling had significant damage to the yield and quality of early indica rice cultivars,especially HT+SL,while the high amylose cultivar ZJZ17 showed a higher negative effect under HT+SL.

Ghost Imaging with High Visibility Using Classical Light Source

We experimentally demonstrate a novel ghost imaging experiment utilizing a classical light source, capable of resolving objects with a high visibility. The experimental results show that our scheme can indeed realize ghost imaging with high visibility for a relatively complicated object composed of three near-ellipse-shaped holes with different dimensions. In our experiment, the largest hole is -36 times of the smMlest one in area. Each of the three holes exhibits high-visibility in excess of 80%. The high visibility and high spatial-resolution advantages of this technique could have applications in remote sensing.

Extreme Light Concentration and High Absorption of the Double Cylindrical Microcavities

We numerically study the enhancement factor of energy density and absorption efficiency inside the double cylindrical microcavities based on a triple-band metamaterial absorber. The compact single unit cell consists of concentric gold rings with a gold disk in the center and a metallic ground plane separated by a dielectric layer. We demonstrate that the multilayer structure with subwavelength electromagnetic confinement allows 104-105-fold enhancement of the electromagnetic energy density inside the double cavities and contains the most energy of the incoming light. Particularly, the enhancement factor of energy density G shows strong ability of localizing light and some regularity as the change of the thickness of the dielectric slab and dielectric constant. At the normal incidence of electromagnetic radiation, the obtained reflection spectra show that the resonance frequencies of the double microcavities operate in the range of 10-30μm. We also calculate the absorption efficiency C, which can reach 95%, 97% and 95% at corresponding frequency by optimizing the structure＇s geometry parameters. Moreover, the proposed structure will be insensitive to the polarization of the incident wave due to the symmetry of the double cylindrical microcavities. The proposed optical metamaterial is a promising candidate as absorbing elements in scientific and technical applications due to its extreme confinement, multiband absorption and polarization insensitivity.

Highly Efficient and Stable Hybrid White Organic Light Emitting Diodes with Controllable Exciton Behavior by a Mixed Bipolar Interlayer

Highly efficient and stable hybrid white organic light-emitting diodes （HWOLEDs） with a mixed bipolar interlayer between fluorescent blue and phosphorescent yellow emitting layers are demonstrated. The bipolar interlayer is a mixture of p-type diphenyl （l0-phenyl-lOH-spiro [acridine-9,9＇-fluoren]-3Lyl） phosphine oxide and n-type 2＇,2- （1,3,5-benzinetriyl）-tris（1-phenyl-l-H-benzimidazole）. The electroluminance and Commission Internationale de l＇Eclairage （CIE1931） coordinates＇ characteristics can be modulated easily by adjusting the ratio of the hole- predominated material to the electron-predominated material in the interlayer. The hybrid WOLED with a p-type：n-type ratio of 1：3 shows a maximum current efficiency and power efficiency of 61.1 ed/A and 55.8 lm/W, respectively, with warm white CIE coordinates of （0.34, 0.43）. The excellent efficiency and adaptive CIE coordi- nates are attributed to the mixed interlayer with improved charge carrier balance, optimized exciton distribution, and enhanced harvesting of singlet and triplet excitons.

Wheat PROTON GRADIENT REGULATION 5 is Involved in Tolerance to Photoinhibition

Wheat （Triticum aestivum L.） often experiences photoinhibition due to strong light during the grain filling stage. As such, increasing the tolerance of wheat to photoinhibition is very desirable in breeding efforts focused on increasing grain yields. Previous reports have suggested that PROTON GRADIENT REGULATION 5 （PGR5） plays a central role in the generation of a proton gradient across the thylakoid membrane （ApH） and in acclimation to high light intensity conditions. Three PGR5 homoeologues were isolated from wheat, and mapped onto chromosomes 7A, 7B and 7D, respectively. The TaPGR5s shared highly similar genomic sequences and gene structures. The transcripts of TaPGR5s were found to be abundantly expressed in the flag leaves, and were transiently up-regulated by treatment with high light. High light treatment inhibited the net photosynthetic rate （Pn） and the maximal quantum yield ofphotosystem II （Fv/Fm）. Further, these inhibitions were more evident in the leaves with reduced expression of TaPGR5s achieved using virus-induced gene silencing methods. Moreover, reducing TaPGR5 expression impaired the induction of non-photochemical quenching （NPQ）, which caused more severe cell membrane damage and lipid peroxidation in high light. Additionally, we observed that TaPGR5s transcripts were more abundantly expressed in the wheat genotypes with higher ms-delayed light emission （ms-DLE）, a value reflecting transthylakoid ApH. These results suggested that TaPGR5s play important roles in the tolerance of wheat to photoinhibition.

Triose phosphate export from chloroplasts and cellular sugar content regulate anthocyanin biosynthesis during high light acclimation

Plants have evolvedmultiple strategies to cope with rapid changes in the environment.During high light(HL)acclimation,the biosynthesis of photoprotective flavonoids,such as anthocyanins,is induced.However,the exact nature of the signal and downstreamfactors forHL induction of flavonoid biosynthesis(FB)is still under debate.Here,we show that carbon fixation in chloroplasts,subsequent export of photosynthates by triose phosphate/phosphate translocator(TPT),and rapid increase in cellular sugar content permit the transcriptional and metabolic activation of anthocyanin biosynthesis during HL acclimation.In combination with genetic and physiological analysis,targeted and whole-transcriptome gene expression studies suggest that reactive oxygen species and phytohormones play only a minor role in rapid HL induction of the anthocyanin branch of FB.In addition to transcripts of FB,sugar-responsive genes showed delayed repression or induction in tpt-2 during HL treatment,and a significant overlapwith transcripts regulated by SNF1-related protein kinase 1(SnRK1)was observed,including a central transcription factor of FB.Analysis of mutants with increased and repressed SnRK1 activity suggests that sugar-induced inactivation of SnRK1 is required for HL-mediated activation of anthocyanin biosynthesis.Our study emphasizes the central role of chloroplasts as sensors for environmental changes as well as the vital function of sugar signaling in plant acclimation.

Study on Kinetics of light-intensity adaptation of Dicrateria inornata.

Light-saturation curves of Dicrateria inornata at various temperatures were determined by using 14C-la belling technique. Kinetics of light-intensity adapation was also analyzed in combination with Chl.a determination and cell enumeration measurements. The response of cellular Chl. a in light transition processes can be appoximately described with the first order kinetic model. The model between temperature and maximum growth rate was established by using the Arrhenius equation.

Beam performance of the SHINE dechirper

A corrugated structure is built and tested on many FEL facilities,providing a'dechirper'mechanism for eliminating energy spread upstream of the undulator section of X-ray FELs.The wakefield effects are here studied for the beam dechirper at the Shanghai high repetition rate XFEL and extreme light facility(SHINE),and compared with analytical calculations.When properly optimized,the energy spread is well compensated.The transverse wakefield effects are also studied,including the dipole and quadrupole effects.By using two orthogonal dechirpers,we confirm the feasibility of restraining the emittance growth caused by the quadrupole wakefield.A more efficient method is thus proposed involving another pair of orthogonal dechirpers.

Genetic analysis of tolerance to photo-oxidative stress induced by high light in winter wheat (Triticum aestivum L.)

High light induced photooxidation （HLIP） usually leads to leaf premature senescence and causes great yield loss in winter wheat. In order to explore the genetic control of wheat tolerance to HLIP stress, a quantitative trait loci （QTL） analysis was conducted on a set of doubled haploid population, derived from two winter wheat cultivars. Actual values of chlorophyll content （Chl）, minimum fluorescence level （Fo）, maximum fluorescence level （Fm）, and the maximum quan^m efficiency of photosystem II （Fv/Fm） under both HLIP and non-stress conditions as well as the ratios of HLIP to non-stress were evaluated. HLIP considerably reduced Chl, Fm, and Fv/Fm, but in- creased Fo, compared with that under non-stress condition. A total of 27, 16, and 28 QTLs were associated with the investigated traits under HLIP and non-stress and the ratios of HLIP to non-stress, respectively. Most of the QTLs for the ratios of HLIP to non-stress collocated or nearly linked with those detected under HLIP condition. HLIP-induced QTLs were mapped on 15 chromosomes, involving in 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 4D, 5B, 6A, 6B, 7A, and 7D while those expressed under non-stress condition involved in nine chromosomes, includ- ing 1B, 1D, 2A, 2B, 3B, 4A, 5A, 5B, and 7A. The expression patterns of QTLs under HLIP condition were different from that under non-stress condition except for six loci on five chromosomes. The phenotypic variance explained by individual QTL ranged from 5.0% to 19.7% under HLIP, 8.3% to 20.8% under non-stress, and 4.9% to 20.2% for the ratios of HLIP to non-stress, respectively. Some markers, for example, Xgwm192 and WMC331 on 4D regulating Chl, Fo, Fm, and Fv/Fm under HLIP condition, might be used in marker assistant selection.

Different B-Type Methionine Sulfoxide Reductases in Chlamydomonas May Protect the Alga against High-Light, Sulfur-Depletion, or Oxidative Stress

The genome of unicellular green alga Chlamydomonas reinhardtii contains four genes encoding B-type methionine sulfoxide reductases, MSRBI.1, MSRB1.2, MSRB2.1, and MSRB2.2, with functions largely unknown. To understand the cell defense system mediated by the methionine suifoxide reductases in Chlamydomonas, we analyzed expression and physiological roles of the MSRBs under different abiotic stress conditions using immunoblotting and quantitative polymerase chain reaction （PCR） analyses. We showed that the MSRB2.2 protein was accumulated in cells treated with high light （1,300 μE-/m2 per s）, whereas MSRBI.1 was accumulated in the cells under 1 mmol/L H2O2 treatment or sulfur depletion. We observed that the cells with the MSRB2.2 knockdown and overexpression displayed increased and decreased sensitivity to high light, respectively, based on in situ chlorophyll a fluorescence measures. We also observed that the cells with the MSRBI.1 knockdown and overexpression displayed decreased and increased tolerance to sulfur-depletion and oxidative stresses, respectively, based on growth and H2- producing performance. The physiological implications revealed from the experimental data highlight the importance of MSRB2.2 and MSRBI.1 in protecting Chlamydomonas cells against adverse conditions such as high-light, sulfur-depletion, and oxidative stresses.

Anthocyanin accumulation in juvenile Schima superba leaves is a growth trade-off by consuming energy for adaptation to high light during summer

Aims Anthocyanin accumulation is the main factor underlying why young plant leaves turn red,and plant growth follows the principle of maximizing the economic efficiency of energy.There is a need to verify the role of young plant leaves turning red and confirm whether anthocyanin accumulation overconsumes the energy of the plant.Methods We compared the different pigment contents,antioxidant capaci-ties,leaf mass per area,photosynthetic characteristics,dark res-piration rates,light compensation points(LCPs)and electron flow distribution of young and mature Schima superba leaves grown under full sunlight and 30%full sunlight conditions.We then exam-ined the correlations between anthocyanins and total antioxidant capacity,photosynthetic pigments,dark respiration rates,LCPs by using linear regression.Finally,we analyzed Pearson correlation coefficients and used principal component analysis to evaluate the interactions of these functional indicators.Important Findings The young leaves of S.superba accumulated anthocyanins in full sunlight but not in 30%full sunlight.Anthocyanins substantially con-tributed to the total antioxidant capacity(accounting for 33.29%)in juvenile S.superba leaves.Young leaves containing more anthocyanin accumulated less reactive oxygen species after high light(HL)treat-ment.However,juvenile leaves accumulating anthocyanins showed 56.97%higher dark respiration rates,24.79%higher LCPs and 5.32%higher allocations of electron flow to photorespiration and lower organic substance accumulation than did those without anthocyanins.These results suggest that young S.superba leaves must consume more energy to accumulate anthocyanins to adapt to HL environments.Therefore,plants sacrifice growth rate to ensure survival,which is a trade-off for their ability to respond to external environments.

Synergistic effect of TiO_2 hierarchical submicrospheres for high performance dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSCs) could be improved by using rationally designed mesoporous film structure for electron collection, dye adsorption and light scattering. The development of a novel double layer film prepared by TiO_2 hierarchical submicrospheres and nanoparticles was reported in this article. The submicrospheres were composed of rutile nanorods of 10 nm diameter and the length of 150–250 nm, which facilitated fast electron transport, charge collection and light scattering. Using a double layer structure consisting of the 10 wt% film as a dye loading layer and the 50 wt% film as the light scattering layer, C101 sensitizer and liquid electrolyte, DSC yielded power conversion efficiency of 9.68% under 1 sun illumination.

Refractive index measurement of dielectric samples using highly focused radially polarized light(Invited Paper)

In this Letter, a refractive index measurement of a dielectric sample using highly focused radially polarized light is reported. Through imaging analysis of the optical field at the pupil plane of a high numerical aperture （NA） objective lens reflected by the sample under study, the Brewster angle is found. Employing a high NA objective lens allows the measurement of multiple angles of incidence from 0° to 64° in a single shot. The refractive index of the sample is estimated using the measured Brewster angle. The experimental results are compared with the theoretical images computed with the Fresnel theory, and a good agreement is obtained.

FEAR OF TRYING A NEW LAW SHEDS LIGHT ON CHINA'S UNUSUALLY HIGH CONVICTION RATE

On August 9,Shandong became the first province in China to abolish performance evaluations based on the number of prosecutions and'cases solved'by police departments.Although the move is ostensibly intended to'redirect energy to public security,crime-prevention,and public assistance,'some lawyers hope it could also improve the'objectivity'of law enforcement in a country where police and prosecutors almost never fail to win in court.

Analysis and simulation of XPM intensity modulation

Based on the split-step Fourier method and small signal analysis, an improved analytical solution which describes the cross-phase modulation (XPM) intensity is derived. It can suppress the spurious XPM intensity modulation efficiently in the whole transmission fiber. Thus it is more coincidence with the practical result. Furthermore, it is convenient, because it is independent of channel separation and the dispersion and nonlinear effects interact through the XPM intensity. A criterion of select the step size is described as the derived XPM intensity modulation being taken into account. It is non-uniform distribution and is the function of average signal power <P(z)> (or z). Compared with the conventional split-step method, the simulation accuracy is improved when the step size is determined by the improved XPM intensity.

Plants response to light stress

Plants require solar energy to grow through oxygenic photosynthesis;however,when light intensity exceeds the optimal range for photosynthesis,it causes abiotic stress and physiological damage in plants.In response to high light stress,plants initiate a series of signal transduction from chloroplasts to whole cells and from locally stressed tissues to the rest of the plant body.These signals trigger a variety of physiological and biochemical reactions intended to mitigate the deleterious effects of high light intensity,such as photodamage and photoinhibition.Light stress protection mechanisms include chloroplastic Reactive oxygen species(ROS)scavenging,chloroplast and stomatal movement,and anthocyanin production.Photosynthetic apparatuses,being the direct targets of photodamage,have also developed various acclimation processes such as thermal energy dissipation through nonphotochemical quenching(NPQ),photorepair of Photosystem II(PSII),and transcriptional regulation of photosynthetic proteins.Fluctuating light is another mild but persistent type of light stress in nature,which unfortunately has been poorly investigated.Current studies,however,suggest that state transitions and cyclic electron transport are the main adaptive mechanisms for mediating fiuctuating light stress in plants.Here,we review the current breadth of knowledge regarding physiological and biochemical responses to both high light stress and fiuctuating light stress.