Photosynthesis is one the most important chemical reaction in plants,and it is the ultimate energy source of any living organisms.The light and dark reactions are two essential phases of photosynthesis.Light reaction ...Photosynthesis is one the most important chemical reaction in plants,and it is the ultimate energy source of any living organisms.The light and dark reactions are two essential phases of photosynthesis.Light reaction harvests light energy to synthesize ATP and NADPH through an electron transport chain,and as well as giving out O_(2);dark reaction fixes CO_(2) into six carbon sugars by utilizing NADPH and energy from ATP.Subsequently,plants convert optical energy into chemical energy for maintaining growth and development through absorbing light energy.Here,firstly,we highlighted the biological importance of photosynthesis,and hormones and metabolites,photosynthetic and regulating enzymes,and signaling components that collectively regulate photosynthesis in tomato.Next,we reviewed the advances in tomato photosynthesis,including two aspects of genetic basis and genetic improvement.Numerous genes regulating tomato photosynthesis are gradually uncovered,and the interaction network among those genes remains to be constructed.Finally,the photosynthesis occurring in fruit of tomato and the relationship between photosynthesis in leaf and fruit were discussed.Leaves and fruits are photosynthate sources and sinks of tomato respectively,and interaction between photosynthesis in leaf and fruit exists.Additionally,future perspectives that needs to be addressed on tomato photosynthesis were proposed.展开更多
The crop yields achieved through traditional plant breeding techniques appear to be nearing a plateau.Therefore,it is essential to accelerate advancements in photosynthesis,the fundamental process by which plants conv...The crop yields achieved through traditional plant breeding techniques appear to be nearing a plateau.Therefore,it is essential to accelerate advancements in photosynthesis,the fundamental process by which plants convert light energy into chemical energy,to further enhance crop yields.Research focused on improving photosynthesis holds significant promise for increasing sustainable agricultural productivity and addressing challenges related to global food security.This review examines the latest advancements and strategies aimed at boosting crop yields by enhancing photosynthetic efficiency.There has been a linear increase in yield over the years in historically released germplasm selected through traditional breeding methods,and this increase is accompanied by improved photosynthesis.We explore various aspects of the light reactions designed to enhance crop yield,including light harvest efficiency through smart canopy systems,expanding the absorbed light spectrum to include far-red light,optimizing non-photochemical quenching,and accelerating electron transport flux.At the same time,we investigate carbon reactions that can enhance crop yield,such as manipulating Rubisco activity,improving the Calvin-Benson-Bassham cycle,introducing CO_(2)concentrating mechanisms in C_(3)plants,and optimizing carbon allocation.These strategies could significantly impact crop yield enhancement and help bridge the yield gap.展开更多
Perchlorate(ClO_(4)^(−))is a type of novel persistent inorganic pollutant that has gained increasing attention because of its high solubility,poor degradability,and widespread distribution.However,the impacts of perch...Perchlorate(ClO_(4)^(−))is a type of novel persistent inorganic pollutant that has gained increasing attention because of its high solubility,poor degradability,and widespread distribution.However,the impacts of perchlorate on aquatic autotrophs such cyanobacterium are still unclear.Herein,Synechocystis sp.PCC6803(Synechocystis)was used to investigate the response mechanisms of perchlorate on cyanobacterium by integrating physiological and transcriptome analyses.Physiological results showed that perchlorate mainly damaged the photosystem of Synechocystis,and the inhibition degree of photosystem II(PSII)was severer than that of photosystem I(PSI).When the exposed cells were moved to a clean medium,the photosynthetic activities were slightly repaired but still lower than in the control group,indicating irreversible damage.Furthermore,perchlorate also destroyed the cellular ultrastructure and induced oxidative stress in Synechocystis.The antioxidant glutathione(GSH)content and the superoxide dismutase(SOD)enzyme activity were enhanced to scavenge harmful reactive oxygen(ROS)in Synechocystis.Transcriptome analysis revealed that the genes associated with“photosynthesis”and“electron transport”were significantly regulated.For instance,most genes related to PSI(e.g.,psaf,psaJ)and the“electron transport chain”were upregulated,whereas most genes related to PSII(e.g.,psbA3,psbD1,psbB,and psbC)were downregulated.Additionally,perchlorate also induced the expression of genes related to the antioxidant system(sod2,gpx,gst,katG,and gshB)to reduce oxidative damage.Overall,this study is the first to investigate the impacts andmechanisms of cyanobacterium under perchlorate stress,which is conducive to assessing the risk of perchlorate in aquatic environments.展开更多
The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and...The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.展开更多
Drought caused by extreme climate change has become more severe and unpredictable,causing imperceptible effects on leaf photosynthesis in foxtail millet.To investigate the damage,we performed light drought(LD)and heav...Drought caused by extreme climate change has become more severe and unpredictable,causing imperceptible effects on leaf photosynthesis in foxtail millet.To investigate the damage,we performed light drought(LD)and heavy drought(HD)treatments at both the elongation(Y)and booting stages to obtain a comprehensive understanding of the morphological,anatomical,physiological,transcriptome,and metabolome levels.Under drought stress,the length and area of leaves decreased,especially during the HD treatment at the booting stage.The number of mesophyll cells and the area of large vascular bundles decreased under LD and HD treatments at the booting stage,with more blurring vascular bundle structure and Kranz anatomy.However,these numbers decreased with no significance under Y-LD and Y-HD treatments at the elongation stage.The net photosynthetic rate,stomatal conductivity,transpiration rate,and intercellular CO_(2)concentration significantly decreased at the booting stage.In addition,the efficiency of electron transfers in photosystem II(PSII)decreased.Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage.The results showed no common differentially enriched pathway in the transcriptome and metabolome under LD treatment.However,32 pathways were enriched in both the transcript and metabolome under HD treatment.Among these,three pathways,including arginine and proline metabolism,tyrosine metabolism,and ubiquinone,along with other terpenoid-quinone biosynthesis pathways,were differentially enriched in both the transcript and metabolome.The accumulation of homogentisate,salidroside,homoprotocatechuate,L-DOPA,tyramine,and L-tyrosine increased under drought stress.Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions,they were down-regulated under HD conditions.The metabolites of ribose-5P,glycerate-3P,D-fructose-1,6P2,and D-fructose-6P were all decreased in both the LD and HD treatments,especially D-fructose-6P,confirming that drought stress harmed the Calvin cycle.The results revealed that regardless of the severity of drought,the photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO_(2)assimilation.展开更多
Grain filling is a critical determinant of yield and quality in rice.This study aims to clarify the association between grain photosynthesis and the filling rate of rice varieties with different grain weights,providin...Grain filling is a critical determinant of yield and quality in rice.This study aims to clarify the association between grain photosynthesis and the filling rate of rice varieties with different grain weights,providing a theoretical foundation for optimizing grain-filling processes.Two rice varieties with similar growth duration but different grain weights were selected:a large-grain variety,Lingliangyou 268(L268),and a small-grain variety,Ruiliangyou 1053(R1053).Differences in grain filling,grain photosynthetic rate,and grain chlorophyll content were systematically examined during the filling stage.Results showed significant differences in grain-filling,grain photosynthetic rate,and grain chlorophyll content between large-grain and small-grain rice varieties.The grain photosynthetic rate of L268 was a significantly higher than R1053.L268 also exhibited significantly higher initial grain filling rate,maximum grainfilling rate,and mean grain filling rate compared to R1053.Throughout the grain filling period,L268 showed higher grain chlorophyll content(including chlorophyll a,chlorophyll b,and total chlorophyll)than R1053.The increase in chlorophyll content,particularly total chlorophyll,enhanced the grain photosynthetic rate during the early and middle stages of grain filling significantly.These findings suggested that rice varieties with higher grain weights exhibited stronger panicle photosynthetic capacity due to their higher chlorophyll content.The enhanced grain photosynthetic rate contributed to improved grain filling and increased grain weight.展开更多
Photosynthesis is the basis of crop growth and is sensitive to stress.Smut(Sporisorium destruens)is the primary disease in the production of broomcorn millet(Panicum miliaceum L.).This study evaluated the effects of i...Photosynthesis is the basis of crop growth and is sensitive to stress.Smut(Sporisorium destruens)is the primary disease in the production of broomcorn millet(Panicum miliaceum L.).This study evaluated the effects of infection with S.destruens on the photosynthesis of the resistant cultivar(BM)and susceptible cultivar(NF).After inoculation,there was a decrease in the chlorophyll content,gas exchange parameters,and chlorophyll fluorescence of the two cultivars.Observation of the ultrastructure of diseased leaves showed that the chloroplasts and mitochondria had abnormal morphology,and some vacuoles appeared.RNA-seq was performed on the flag leaves after inoculation.In addition to the resistant and susceptible cultivars,the diseased leaves developed from inflorescences were defined as S2.The analysis showed that the pathways related to photosynthesis stimulated some differentially expressed genes(DEGs)after infection with S.destruens.More DEGs were induced in the susceptible broomcorn millet NF than in the resistant broomcorn millet BM,and most of those genes were downregulated.The number of DEGs induced by S2 was greater than that in susceptible cultivar NF,and most of them were upregulated.These results indicate that infection with S.destruens affects the normal photosynthetic performance of broomcorn millet.Understanding the mechanism between S.destruens,photosynthesis,and broomcorn millet is an effective measure to prevent the occurrence of smut and enhance its resistance.展开更多
The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and ...The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].展开更多
The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analys...The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analysis indicate that introducing pyrazine units enhances charge migration,leading to increased accumulation of photoinduced electrons on these units,thereby facilitating the two-site,two-electron ORR.Inspired by these theoretical insights,this work designed and fabricated a triazine-pyrazine-based covalent organic framework materials(TTDN-COFs)for H_(2)O_(2) photosynthesis via a polarity-functionalization strategy.The TTDN-COFs demonstrate a significant improvement in the photocatalytic H_(2)O_(2) production rate,reaching 2757.6μmol h^(-1) g^(-1) in pure water–3.2 times higher than that of the triazine-based COFs(TTPH-COFs).Experimental results and theoretical calculations confirm that the incorporation of pyrazine units not only enhances polarization,promoting the separation and migration of charge carriers,but also facilitates the formation of endoperoxide at both the triazine and pyrazine units.The dual adsorption activation sites lower the activation energy barrier for O_(2),thereby accelerating the overall reaction kinetics.These findings highlight the potential of functional-group-mediated polarization engineering as a promising strategy for developing COFs-based H_(2)O_(2) photosynthesis with dual activation sites.展开更多
Pd catalyst with high activity and selectivity for O_(2)reduction to H_(2)O_(2)is highly desirable.However,metallic Pd catalyst suffers from limited activity and selectivity in H_(2)O_(2)photosynthesis due to intrinsi...Pd catalyst with high activity and selectivity for O_(2)reduction to H_(2)O_(2)is highly desirable.However,metallic Pd catalyst suffers from limited activity and selectivity in H_(2)O_(2)photosynthesis due to intrinsically strong O_(2)adsorption at Pd atom sites.Herein,a strategy is proposed to modulate the electronic structure,aiming to weaken O_(2)adsorption and further enhance O_(2)-reduction selectivity through the creation of highly dispersed and electron-enriched Pd^(δ-)atom sites.To achieve this,a novel photochemical plating approach is employed to selectively grow vertical Bi nanosheets on the(010)facet of BiVO_(4).This process confines highly dispersed Pd atoms within the Bi nanosheets,forming a PdBi cocatalyst that significantly boosts H_(2)O_(2)photosynthesis.Notably,the optimized PdBi/BiVO_(4)photocatalyst achieves a high H_(2)O_(2)production concentration of 2246.43μmol L−1,with an apparent quantum efficiency(AQE)of 11.16%,realizing a 1.74-fold enhancement in activity compared to Pd/BiVO_(4)(1289.28μmol L^(−1)).Theoretical calculation and experimental results confirm that the vertical-growth Bi nanosheets induce the formation of well-dispersed and electron-enriched Pd^(δ−)atom sites.This accordingly increases the antibonding-orbital occupancy of Pd-O_(ads),thereby weakening O_(2)adsorption and ultimately facilitating selective O_(2)reduction for photocatalytic H_(2)O_(2)production.This rational design of Pd-based catalysts provides a promising strategy for modulating the electronic structure of active atoms to advance artificial photosynthesis.展开更多
Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four plan...Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.展开更多
Dynamics of dry- or fresh-weight of fruit, peel photosynthetic rate and chlorophyll content, and the characteristics of translocation and distribution of radiolabelled assimilates from leaf or fruit were examined in d...Dynamics of dry- or fresh-weight of fruit, peel photosynthetic rate and chlorophyll content, and the characteristics of translocation and distribution of radiolabelled assimilates from leaf or fruit were examined in developing satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa wase) fruit from primary stage of fruit enlargement up to fruit full ripe. Change in fruit photosynthetic rate was some what related to the change in the chlorophyll content of peel. Fruit photosynthetic rate markedly declined as chlorophyll degradation occurred in the peel. Before full ripe stage of the fruit, photosynthates produced by a 14C-fed leaf were mainly distributed to juice sacs even during periods when dry matter accumulation in peel was more rapid than that in juice sacs. At the full ripe stage, peel photosynthetic rate approached zero and peel became the major sink of leaf photosynthates. Most of the peel assimilates, however, remained in situ for up to 48 h after feeding 14CO 2 to the fruit, only a small portion being transported to other parts of fruit. The percentage of fruit photosynthates exported decreased with fruit development and ripening, but the peak rate of export to juice sacs amount to as high as 12%. The sugar content and dry weights of peel and juice sacs in shaded fruit were lower than that in the control fruit. These results show that peel assimilate was mainly consumed in peel respiration and growth and thus the dependence on leaf photosynthates decreased. Part of this assimiate was used in sugar accumulation in juice sacs of fruit.展开更多
The increase of atmospheric CO 2 concentration is indisputable. In such condition, photosynthetic response of leaf is relatively well studied, while the comparison of that between single leaf and whole canopy is less...The increase of atmospheric CO 2 concentration is indisputable. In such condition, photosynthetic response of leaf is relatively well studied, while the comparison of that between single leaf and whole canopy is less emphasized. The stimulation of elevated CO 2 on canopy photosynthesis may be different from that on single leaf level. In this study, leaf and canopy photosynthesis of rice (Oryza sativa L.) were studied throughout the growing season. High CO 2 and temperature had a synergetic stimulation on single leaf photosynthetic rate until grain filling. Photosynthesis of leaf was stimulated by high CO 2, although the stimulation was decreased by higher temperature at grain filling stage. On the other hand, the simulation of elevated CO 2 on canopy photosynthesis leveled off with time. Stimulation at canopy level disappeared by grain filling stage in both temperature treatments. Green leaf area index was not significantly affected by CO 2 at maturity, but greater in plants grown at higher temperature. Leaf nitrogen content decreased with the increase of CO 2 concentration although it was not statistically significant at maturity. Canopy respiration rate increased at flowering stage indicating higher carbon loss. Shading effect caused by leaf development reached maximum at flowering stage. The CO 2 stimulation on photosynthesis was greater in single leaf than in canopy. Since enhanced CO 2 significantly increased biomass of rice stems and panicles, increase in canopy respiration caused diminishment of CO 2 stimulation in canopy net photosynthesis. Leaf nitrogen in the canopy level decreased with CO 2 concentration and may eventually hasten CO 2 stimulation on canopy photosynthesis. Early senescence of canopy leaves in high CO 2 is also a possible cause.展开更多
The characteristics of photosynthesis and water metabolism of Caragana microphylla Lam.,C. davazamcii Sancz. and C. korshinskii Kom. populations in different sites (117.6o-105.7o E, 44.6o-38.8o N)were studied. (1) Fro...The characteristics of photosynthesis and water metabolism of Caragana microphylla Lam.,C. davazamcii Sancz. and C. korshinskii Kom. populations in different sites (117.6o-105.7o E, 44.6o-38.8o N)were studied. (1) From the east to the west, the responses of the three species to photosyntheticallyavailable radiation (PAR) in net photosynthesis rate increased, the relative humidity of the air whichcorresponded to the occurrence of maximum photosynthesis rate decreased, and the corresponding airtemperature increased. Along the same gradient, the before-noon superiority of the photosynthesis be-came evident, and the photosynthesis rate and the light use efficiency (LUE ) increased, while the transp-iration rate decreased, thus the water use efficiency (WUE ) increased notably, and the leaf water contentdecreased gradually. From the east to the west, the plants took a water-saving strategy step by step withhigher photosynthesis rate and lower transpiration rate. These physiological changes in the plants wereadaptable to the conditions of light, temperature and humidity in the habitat of the plants, and might be thebiological foundation for the geographical transition among C. microphylla , C. davazamcii and C. korshinskii.(2) The adaptation of photosynthetic system of C. microphylla , C. davazamcii and C. korshinskii to PAR, airhumidity and temperature exhibited the interspecific continuity, which was consistent with theenvironmental gradient. In different species and different sites, the diurnal changes of net photosynthesisrate, the daily cumulative value of net photosynthesis, the diurnal changes of transpiration rate, the dailycumulative value of transpiration, the water use efficiency and the diurnal changes of leaf water contentvaried with longitudinal descent (from the east to the west). The characteristics of photosynthesis andwater metabolism indicated that the geographical transition among C. microphylla , C. davazamcii and C.korshinskii was in gradual change, and these three species formed a geographical cline.展开更多
Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in ...Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in the Maowusu Sand Area were analyzed and the relation among these characteristics and the resource utilization efficiency, taxonomic categories and growth forms of the species were assessed. The results showed that species from Chenopodiaceae, Gramineae, Leguminosae which possessed the C 4 photosynthesis pathway, or C 3 pathway and also with nitrogen_fixation capacities had higher or the highest P n values, i.e., 20～30 μmol CO 2·m -2 ·s -1 , while that of evergreen shrub of Pinaceae had the lowest P n values, i.e., 0～5 μmol CO 2·m -2 ·s -1 . Those species from Compositae, Scrophulariaceae, and Gramineae with C 3 pathway but no N_fixation capacity had the highest E rates, i.e., 20～30 mmol H 2O·m -2 ·s -1 and again the evergreen shrub together with some species from Salicaceae and Compositae had the lowest E rates, i.e., 0～5 mmol H 2O·m -2 ·s -1 . Species from Leguminosae, Gramineae and Chenopodiaceae with C 4 pathway or C 3 pathway with N_fixation capacity, both shrubs and grasses, generally had higher WUE . However, even the physiological traits of the same species were habitat_ and season_specific. The values of both P n and E in late summer were much higher than those in early summer, with average increases of 26%, 40% respectively in the four habitats. WUE in late summer was, however, 12% lower. Generally, when the environments became drier as a result of habitats changed, i.e., in the order of wetland, lowland, fixed sand dune and shifting sand dune, P n and E decreased but WUE increased.展开更多
Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer con...Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer conductance. Leuning in his revised Ball's model replaced relative humidity with VPD s (the vapor pressure deficit from stomatal pore to leaf surface) and thereby made the relation with transpiration more straightforward, and made it possible for the regulation of transpiration and the influence of boundary layer conductance to be integrated into the combined model. If the differences in water vapor and CO 2 concentration between leaf and ambient air are considered, VPD s , the evaporative demand, is influenced by stomatal and boundary layer conductance. The physiological responses of photosynthesis, transpiration, and stomatal function, and the changes of intercellular CO 2 and water use efficiency to environmental factors, such as wind speed, photon flux density, leaf temperature and ambient CO 2, are analyzed. It is shown that if the boundary layer conductance drops to a level comparable with stomatal conductance, the results of simulation by the model presented here differ significantly from those by the previous model, and, in some cases, are more realistic than the latter.展开更多
Four rice ( Oryza sativa L.) cultivars 'IR72', 'Tesanai 2', 'Guichao 2' and 'IIyou 4480' were grown in two plastic house (15 m×3 m) with 35 μmol/mol and 60 μmol/mol CO 2 conc...Four rice ( Oryza sativa L.) cultivars 'IR72', 'Tesanai 2', 'Guichao 2' and 'IIyou 4480' were grown in two plastic house (15 m×3 m) with 35 μmol/mol and 60 μmol/mol CO 2 concentration which was controlled by computer. As compared with rice at ambient 35 μmol/mol CO 2, the changes in photosynthetic rate at elevated CO 2 showed up_regulation ('IR72' and 'Tesanai 2'), stable (unchanged) in 'Guichao 2' and down_regulation type ('IIyou 4480'). Growth rate, panicle weight, integrated water use efficiency (WUE) calculated from Δ 13 C and the capacity of scavenging DPPH · (1,1_diphenyl_2_picrylhydrazyl) free radical were increased at elevated CO 2. An increment in total biomass was observed in three cultivars by elevated CO 2, with the exception of 'IIyou 4480'. Ratios of panicle weight/total biomass were altered to different extents in tested cultivars by elevated CO 2. When leaf segments were subjected to PEG osmotic stress, the electrolyte leakage rate from leaves grown at elevated CO 2 was less than that at 35 μmol/mol CO 2. Those intraspecific variations of rice imply a possibility for selecting cultivars with maximal productivity and high tolerance to stresses adapted to elevated CO 2 in the future.展开更多
[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ni...[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance （Gs）,transpiration rate （Tr） and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate （Pn） and photosynthetic water use efficiency （WUE） in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate.展开更多
Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content an...Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content and chloroplast structure little changed in the course of desiccation, therefore has been called homoiochlorophyllous desiccation-tolerant plants (HDTs). Another type of resurrection angiosperms that lost its chlorophyll dining desiccation is called poikilochlorophyllous desiccation-tolerant plants (PDTs). HDTs have been received more attention because of simplicity of protection mechanism which is much easy to the study and utilization of the desiccation tolerance of resurrection angiosperms. Recent advances in studies of photosynthesis of resurrection angiosperms indicate that photochemical activities are sensitive indicators for the study of physiological state of resurrection angiosperms during desiccation and rehydration. Photochemical activities of resurrection angiosperms are inhibited with loss of water similar to those of general plants, however, the magic thing is that they could reactivate rapidly during rehydration even losing more than 95% water. Up-regulations in xanthophyll cycle and antioxidative systems as well as preservation in integrity and stability of photosynthetic membranes during desiccation may be very important to desiccation tolerance of resurrection angiosperms. The fact that phosphate treatment in rehydration stage also strongly influences resurrection indicated importance of studies on rehydration stages of resurrection angiosperms.展开更多
[Objective] This study aimed to test whether salicylic acid （SA） can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. [Method] T...[Objective] This study aimed to test whether salicylic acid （SA） can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. [Method] The tobacco plants under subdued light were foliar-sprayed with 100 mg/L of SA. Then, the physiological in-dices such as plant fresh weight and dry weight, chlorophyl content, photosynthetic parameters and chlorophyl fluorescence parameters were measured. SPSS17.0 and Excellwere adopted for variance analysis and significance test. [Result] The leaf photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） of tobacco plants in subdued light were al decreased while the intercellular CO2 con-centration （Ci） was increased, suggesting that non-stomatal limitation led to the de-crease of Pn under weak light intensity stress. SA released the inhibition of tobacco plant growth in weak light, as it elevated the leaf photosynthetic rate, the maximum photochemical efficiency of PSⅡ, potential activity of PSⅡ, effective photochemical efficiency of PSⅡ and photochemical quenching coefficient in weak light significant-ly, and reduced the non-photochemical quenching coefficient. [Conclusion] SA has significant effects on the photosynthetic characteristics of flue-cured tobacco in weak light, and it can improve the synthesis or distribution of photosynthesis product, and the efficiency of light energy, conducive to plant growth and development.展开更多
基金supported by grants from the National Key Research&Development Plan(Grants Nos.2022YFF10030022022YFD1200502)+7 种基金National Natural Science Foundation of China(Grant Nos.3237269631991182)Wuhan Biological Breeding Major Project(Grant No.2022021302024852)Key Project of Hubei Hongshan Laboratory(2021hszd007)HZAU-AGIS Cooperation Fund(Grant No.SZYJY2023022)Funds for High Quality Development of Hubei Seed Industry(HBZY2023B004)Hubei Agriculture Research System(2023HBSTX4-06)Hubei Key Research&Development Plan(Grants Nos.2022BBA0066,2022BBA0062)。
文摘Photosynthesis is one the most important chemical reaction in plants,and it is the ultimate energy source of any living organisms.The light and dark reactions are two essential phases of photosynthesis.Light reaction harvests light energy to synthesize ATP and NADPH through an electron transport chain,and as well as giving out O_(2);dark reaction fixes CO_(2) into six carbon sugars by utilizing NADPH and energy from ATP.Subsequently,plants convert optical energy into chemical energy for maintaining growth and development through absorbing light energy.Here,firstly,we highlighted the biological importance of photosynthesis,and hormones and metabolites,photosynthetic and regulating enzymes,and signaling components that collectively regulate photosynthesis in tomato.Next,we reviewed the advances in tomato photosynthesis,including two aspects of genetic basis and genetic improvement.Numerous genes regulating tomato photosynthesis are gradually uncovered,and the interaction network among those genes remains to be constructed.Finally,the photosynthesis occurring in fruit of tomato and the relationship between photosynthesis in leaf and fruit were discussed.Leaves and fruits are photosynthate sources and sinks of tomato respectively,and interaction between photosynthesis in leaf and fruit exists.Additionally,future perspectives that needs to be addressed on tomato photosynthesis were proposed.
基金funded by CAS Project for Young Scientists in Basic Research(YSBR-072-8)National Key Research and Development Program of China(2021YFF1000203 and 2022YFF1001704)。
文摘The crop yields achieved through traditional plant breeding techniques appear to be nearing a plateau.Therefore,it is essential to accelerate advancements in photosynthesis,the fundamental process by which plants convert light energy into chemical energy,to further enhance crop yields.Research focused on improving photosynthesis holds significant promise for increasing sustainable agricultural productivity and addressing challenges related to global food security.This review examines the latest advancements and strategies aimed at boosting crop yields by enhancing photosynthetic efficiency.There has been a linear increase in yield over the years in historically released germplasm selected through traditional breeding methods,and this increase is accompanied by improved photosynthesis.We explore various aspects of the light reactions designed to enhance crop yield,including light harvest efficiency through smart canopy systems,expanding the absorbed light spectrum to include far-red light,optimizing non-photochemical quenching,and accelerating electron transport flux.At the same time,we investigate carbon reactions that can enhance crop yield,such as manipulating Rubisco activity,improving the Calvin-Benson-Bassham cycle,introducing CO_(2)concentrating mechanisms in C_(3)plants,and optimizing carbon allocation.These strategies could significantly impact crop yield enhancement and help bridge the yield gap.
基金supported by the Project of Chinese Manned Spaceflight(No.YYWT-0801-EXP-09)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA17010502)Jiangsu Province Ecological Environment Scientific Research Project(No.2022008).
文摘Perchlorate(ClO_(4)^(−))is a type of novel persistent inorganic pollutant that has gained increasing attention because of its high solubility,poor degradability,and widespread distribution.However,the impacts of perchlorate on aquatic autotrophs such cyanobacterium are still unclear.Herein,Synechocystis sp.PCC6803(Synechocystis)was used to investigate the response mechanisms of perchlorate on cyanobacterium by integrating physiological and transcriptome analyses.Physiological results showed that perchlorate mainly damaged the photosystem of Synechocystis,and the inhibition degree of photosystem II(PSII)was severer than that of photosystem I(PSI).When the exposed cells were moved to a clean medium,the photosynthetic activities were slightly repaired but still lower than in the control group,indicating irreversible damage.Furthermore,perchlorate also destroyed the cellular ultrastructure and induced oxidative stress in Synechocystis.The antioxidant glutathione(GSH)content and the superoxide dismutase(SOD)enzyme activity were enhanced to scavenge harmful reactive oxygen(ROS)in Synechocystis.Transcriptome analysis revealed that the genes associated with“photosynthesis”and“electron transport”were significantly regulated.For instance,most genes related to PSI(e.g.,psaf,psaJ)and the“electron transport chain”were upregulated,whereas most genes related to PSII(e.g.,psbA3,psbD1,psbB,and psbC)were downregulated.Additionally,perchlorate also induced the expression of genes related to the antioxidant system(sod2,gpx,gst,katG,and gshB)to reduce oxidative damage.Overall,this study is the first to investigate the impacts andmechanisms of cyanobacterium under perchlorate stress,which is conducive to assessing the risk of perchlorate in aquatic environments.
基金funding from the Ongoing Research Funding program,ORF-2025-298,King Saud University,Riyadh,Saudi Arabia.
文摘The low efficiency of phytoextraction of lead(Pb)from agricultural fields poses a significant agricultural challenge.Organic chelating agents can influence Pb bioavailability in soil,affecting its uptake,transport,and toxicity in plants.This study aimed to assess the impact of citric acid(CA)and diethylenetriaminepentaacetic acid(DTPA)on chelate-assisted phytoextraction of Pb and its effect on growth and physiology of two cultivars(07001;07002)of mung bean(Vigna radiata).The cultivars of mung bean were exposed to 60 lead chloride(PbCl_(2))solution,mg⋅L-1with or without the addition of 300 CA or 500 DTPA,until maturity.The exposure of plants to Pb mg⋅L^(-1) mg⋅L^(-1) stress increased the accumulation of Pb in roots(49%of control),stems(58%of control),leaves(67%of control),and seeds(61%of control).Maximum accumulation of Pb was observed in roots and the least accumulation was found in seeds of both mung bean cultivars.The extent of Pb accumulation in different plant parts correlated positively with Pb toxicity and reduced growth of both mung bean cultivars(33%to 40%).The cultivar cv 07001 was more susceptible to Pb stress.The addition of CA and DTPA increased the accumulation of Pb in plant parts of mung bean cultivars-phytoextraction(10.8%to 21.5%).However,the addition of CA partitioned Pb in vegetative parts,i.e.,root,stem thus mitigated the toxic effects of Pb on the growth of mung bean cultivars(6.25%–10.5%).In contrast,the addition of DTPA had adverse effects on the growth of mung bean cultivars.The addition of CA facilitated a greater uptake and accumulation of nitrogen,phosphorous,and potassium in the roots and leaves of mung bean cultivars.In addition,CA also improved the photosynthetic pigments(11%–14%)and photosynthetic rate(5%–12%)under both control and Pb stress conditions.The ameliorative effect of CA on the photosynthetic capacity of mung bean cultivars was likely associated with photosynthetic metabolic factors rather than stomatal factors.Furthermore,cv 07002 was found to be more tolerant to Pb stress and showed better performance in CA application.Overall,the application of CA demonstrated significant potential as a chelating agent for remediating Pb-contaminated soil.
基金supported by the National Key Research and Development Program of China(2019YFD1002204)the National Natural Science Foundation for Youth of China(31901505)the Shenyang Agricultural University Introduced Talent Research Project,China(20153042)。
文摘Drought caused by extreme climate change has become more severe and unpredictable,causing imperceptible effects on leaf photosynthesis in foxtail millet.To investigate the damage,we performed light drought(LD)and heavy drought(HD)treatments at both the elongation(Y)and booting stages to obtain a comprehensive understanding of the morphological,anatomical,physiological,transcriptome,and metabolome levels.Under drought stress,the length and area of leaves decreased,especially during the HD treatment at the booting stage.The number of mesophyll cells and the area of large vascular bundles decreased under LD and HD treatments at the booting stage,with more blurring vascular bundle structure and Kranz anatomy.However,these numbers decreased with no significance under Y-LD and Y-HD treatments at the elongation stage.The net photosynthetic rate,stomatal conductivity,transpiration rate,and intercellular CO_(2)concentration significantly decreased at the booting stage.In addition,the efficiency of electron transfers in photosystem II(PSII)decreased.Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage.The results showed no common differentially enriched pathway in the transcriptome and metabolome under LD treatment.However,32 pathways were enriched in both the transcript and metabolome under HD treatment.Among these,three pathways,including arginine and proline metabolism,tyrosine metabolism,and ubiquinone,along with other terpenoid-quinone biosynthesis pathways,were differentially enriched in both the transcript and metabolome.The accumulation of homogentisate,salidroside,homoprotocatechuate,L-DOPA,tyramine,and L-tyrosine increased under drought stress.Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions,they were down-regulated under HD conditions.The metabolites of ribose-5P,glycerate-3P,D-fructose-1,6P2,and D-fructose-6P were all decreased in both the LD and HD treatments,especially D-fructose-6P,confirming that drought stress harmed the Calvin cycle.The results revealed that regardless of the severity of drought,the photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO_(2)assimilation.
基金supported by the Hunan Provincial Natural Science Foundation of China(Grant No.2023JJ40309)the Changsha Outstanding Innovative Youth Training Program(kq2306015).
文摘Grain filling is a critical determinant of yield and quality in rice.This study aims to clarify the association between grain photosynthesis and the filling rate of rice varieties with different grain weights,providing a theoretical foundation for optimizing grain-filling processes.Two rice varieties with similar growth duration but different grain weights were selected:a large-grain variety,Lingliangyou 268(L268),and a small-grain variety,Ruiliangyou 1053(R1053).Differences in grain filling,grain photosynthetic rate,and grain chlorophyll content were systematically examined during the filling stage.Results showed significant differences in grain-filling,grain photosynthetic rate,and grain chlorophyll content between large-grain and small-grain rice varieties.The grain photosynthetic rate of L268 was a significantly higher than R1053.L268 also exhibited significantly higher initial grain filling rate,maximum grainfilling rate,and mean grain filling rate compared to R1053.Throughout the grain filling period,L268 showed higher grain chlorophyll content(including chlorophyll a,chlorophyll b,and total chlorophyll)than R1053.The increase in chlorophyll content,particularly total chlorophyll,enhanced the grain photosynthetic rate during the early and middle stages of grain filling significantly.These findings suggested that rice varieties with higher grain weights exhibited stronger panicle photosynthetic capacity due to their higher chlorophyll content.The enhanced grain photosynthetic rate contributed to improved grain filling and increased grain weight.
基金supported by the China Agriculture Research System of MOF and MARA(CARS-06-A26)the“Two-chain”Fusion Crop Breeding Key Project of Shaanxi,China(2021-LLRH-07)。
文摘Photosynthesis is the basis of crop growth and is sensitive to stress.Smut(Sporisorium destruens)is the primary disease in the production of broomcorn millet(Panicum miliaceum L.).This study evaluated the effects of infection with S.destruens on the photosynthesis of the resistant cultivar(BM)and susceptible cultivar(NF).After inoculation,there was a decrease in the chlorophyll content,gas exchange parameters,and chlorophyll fluorescence of the two cultivars.Observation of the ultrastructure of diseased leaves showed that the chloroplasts and mitochondria had abnormal morphology,and some vacuoles appeared.RNA-seq was performed on the flag leaves after inoculation.In addition to the resistant and susceptible cultivars,the diseased leaves developed from inflorescences were defined as S2.The analysis showed that the pathways related to photosynthesis stimulated some differentially expressed genes(DEGs)after infection with S.destruens.More DEGs were induced in the susceptible broomcorn millet NF than in the resistant broomcorn millet BM,and most of those genes were downregulated.The number of DEGs induced by S2 was greater than that in susceptible cultivar NF,and most of them were upregulated.These results indicate that infection with S.destruens affects the normal photosynthetic performance of broomcorn millet.Understanding the mechanism between S.destruens,photosynthesis,and broomcorn millet is an effective measure to prevent the occurrence of smut and enhance its resistance.
文摘The increasing dependence on fossil fuels and the consequent CO_(2)emissions have prompted urgent energy and environmental challenges[1,2].Solar-driven CO_(2)conversion into value-added fuels offers a sustainable and promising solution to these issues[3].However,the practical implementation of CO_(2)photoreduction is constrained by low efficiency,primarily due to the rapid recombination of photogenerated electron-hole pairs[4].
文摘The two-electron oxygen reduction reaction(ORR)for H_(2)O_(2) photosynthesis is often hindered by sluggish charge kinetics and a limited number of activation sites.Theoretical predictions based on dipole moment analysis indicate that introducing pyrazine units enhances charge migration,leading to increased accumulation of photoinduced electrons on these units,thereby facilitating the two-site,two-electron ORR.Inspired by these theoretical insights,this work designed and fabricated a triazine-pyrazine-based covalent organic framework materials(TTDN-COFs)for H_(2)O_(2) photosynthesis via a polarity-functionalization strategy.The TTDN-COFs demonstrate a significant improvement in the photocatalytic H_(2)O_(2) production rate,reaching 2757.6μmol h^(-1) g^(-1) in pure water–3.2 times higher than that of the triazine-based COFs(TTPH-COFs).Experimental results and theoretical calculations confirm that the incorporation of pyrazine units not only enhances polarization,promoting the separation and migration of charge carriers,but also facilitates the formation of endoperoxide at both the triazine and pyrazine units.The dual adsorption activation sites lower the activation energy barrier for O_(2),thereby accelerating the overall reaction kinetics.These findings highlight the potential of functional-group-mediated polarization engineering as a promising strategy for developing COFs-based H_(2)O_(2) photosynthesis with dual activation sites.
基金supported by the National Natural Science Foundation of China(22178276,221760110,22178275)the Postdoctoral Fellowship Program of CPSF(GZC20240888)the Postdoctoral Project of Hubei Province(2024HBBHCXB053).
文摘Pd catalyst with high activity and selectivity for O_(2)reduction to H_(2)O_(2)is highly desirable.However,metallic Pd catalyst suffers from limited activity and selectivity in H_(2)O_(2)photosynthesis due to intrinsically strong O_(2)adsorption at Pd atom sites.Herein,a strategy is proposed to modulate the electronic structure,aiming to weaken O_(2)adsorption and further enhance O_(2)-reduction selectivity through the creation of highly dispersed and electron-enriched Pd^(δ-)atom sites.To achieve this,a novel photochemical plating approach is employed to selectively grow vertical Bi nanosheets on the(010)facet of BiVO_(4).This process confines highly dispersed Pd atoms within the Bi nanosheets,forming a PdBi cocatalyst that significantly boosts H_(2)O_(2)photosynthesis.Notably,the optimized PdBi/BiVO_(4)photocatalyst achieves a high H_(2)O_(2)production concentration of 2246.43μmol L−1,with an apparent quantum efficiency(AQE)of 11.16%,realizing a 1.74-fold enhancement in activity compared to Pd/BiVO_(4)(1289.28μmol L^(−1)).Theoretical calculation and experimental results confirm that the vertical-growth Bi nanosheets induce the formation of well-dispersed and electron-enriched Pd^(δ−)atom sites.This accordingly increases the antibonding-orbital occupancy of Pd-O_(ads),thereby weakening O_(2)adsorption and ultimately facilitating selective O_(2)reduction for photocatalytic H_(2)O_(2)production.This rational design of Pd-based catalysts provides a promising strategy for modulating the electronic structure of active atoms to advance artificial photosynthesis.
文摘Single-atom catalysts are promising for H_(2)O_(2) photosynthesis from O_(2) and H_(2)O,but their efficiency is still limited by the ill-defined electronic structure.In this study,Co single-atoms with unique four planar N-coordination and one axial P-coordination(Co-N_(4)P_(1))are decorated on the lateral edges of nanorod-like crystalline g-C_(3)N_(4)(CCN)photocatalysts.Significantly,the electronic structures of central Co as active sites for O_(2) reduction reaction(ORR)and planar N-coordinator as active sites for H_(2)O oxidation reaction(WOR)in Co-N_(4)P_(1) can be well regulated by the synergetic effects of introducing axial P-coordinator,in contrast to the decorated Co single-atoms with only four planar N-coordination(Co-N_(4)).Specifically,directional photoelectron accumulation at central Co active sites,induced by an introduced midgap level in Co-N_(4)P_(1),mediates the ORR active sites from 4e–-ORR-selective terminal–NH_(2) sites to 2e–-ORR-selective Co sites,moreover,an elevated d-band center of Co 3d orbital strengthens ORR intermediate*OOH adsorption,thus jointly facilitating a highly selective and active 2e^(–)-ORR pathway to H_(2)O_(2) photosynthesis.Simultaneously,a downshifted p-band center of N_(2)p orbital in Co-N_(4)P_(1) weakens WOR intermediate*OH adsorption,thus enabling a preferable 2e^(–)-WOR pathway toward H_(2)O_(2) photosynthesis.Subsequently,Co-N_(4)P_(1) exhibits exceptional H_(2)O_(2) photosynthesis efficiency,reaching 295.6μmol g^(-1) h^(-1) with a remarkable solar-to-chemical conversion efficiency of 0.32%,which is 15 times that of Co-N_(4)(19.2μmol g^(-1) h^(-1))and 10 times higher than CCN(27.6μmol g^(-1) h^(-1)).This electronic structure modulation on single-atom catalysts offers a promising strategy for boosting the activity and selectivity of H_(2)O_(2) photosynthesis.
文摘Dynamics of dry- or fresh-weight of fruit, peel photosynthetic rate and chlorophyll content, and the characteristics of translocation and distribution of radiolabelled assimilates from leaf or fruit were examined in developing satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa wase) fruit from primary stage of fruit enlargement up to fruit full ripe. Change in fruit photosynthetic rate was some what related to the change in the chlorophyll content of peel. Fruit photosynthetic rate markedly declined as chlorophyll degradation occurred in the peel. Before full ripe stage of the fruit, photosynthates produced by a 14C-fed leaf were mainly distributed to juice sacs even during periods when dry matter accumulation in peel was more rapid than that in juice sacs. At the full ripe stage, peel photosynthetic rate approached zero and peel became the major sink of leaf photosynthates. Most of the peel assimilates, however, remained in situ for up to 48 h after feeding 14CO 2 to the fruit, only a small portion being transported to other parts of fruit. The percentage of fruit photosynthates exported decreased with fruit development and ripening, but the peak rate of export to juice sacs amount to as high as 12%. The sugar content and dry weights of peel and juice sacs in shaded fruit were lower than that in the control fruit. These results show that peel assimilate was mainly consumed in peel respiration and growth and thus the dependence on leaf photosynthates decreased. Part of this assimiate was used in sugar accumulation in juice sacs of fruit.
文摘The increase of atmospheric CO 2 concentration is indisputable. In such condition, photosynthetic response of leaf is relatively well studied, while the comparison of that between single leaf and whole canopy is less emphasized. The stimulation of elevated CO 2 on canopy photosynthesis may be different from that on single leaf level. In this study, leaf and canopy photosynthesis of rice (Oryza sativa L.) were studied throughout the growing season. High CO 2 and temperature had a synergetic stimulation on single leaf photosynthetic rate until grain filling. Photosynthesis of leaf was stimulated by high CO 2, although the stimulation was decreased by higher temperature at grain filling stage. On the other hand, the simulation of elevated CO 2 on canopy photosynthesis leveled off with time. Stimulation at canopy level disappeared by grain filling stage in both temperature treatments. Green leaf area index was not significantly affected by CO 2 at maturity, but greater in plants grown at higher temperature. Leaf nitrogen content decreased with the increase of CO 2 concentration although it was not statistically significant at maturity. Canopy respiration rate increased at flowering stage indicating higher carbon loss. Shading effect caused by leaf development reached maximum at flowering stage. The CO 2 stimulation on photosynthesis was greater in single leaf than in canopy. Since enhanced CO 2 significantly increased biomass of rice stems and panicles, increase in canopy respiration caused diminishment of CO 2 stimulation in canopy net photosynthesis. Leaf nitrogen in the canopy level decreased with CO 2 concentration and may eventually hasten CO 2 stimulation on canopy photosynthesis. Early senescence of canopy leaves in high CO 2 is also a possible cause.
文摘The characteristics of photosynthesis and water metabolism of Caragana microphylla Lam.,C. davazamcii Sancz. and C. korshinskii Kom. populations in different sites (117.6o-105.7o E, 44.6o-38.8o N)were studied. (1) From the east to the west, the responses of the three species to photosyntheticallyavailable radiation (PAR) in net photosynthesis rate increased, the relative humidity of the air whichcorresponded to the occurrence of maximum photosynthesis rate decreased, and the corresponding airtemperature increased. Along the same gradient, the before-noon superiority of the photosynthesis be-came evident, and the photosynthesis rate and the light use efficiency (LUE ) increased, while the transp-iration rate decreased, thus the water use efficiency (WUE ) increased notably, and the leaf water contentdecreased gradually. From the east to the west, the plants took a water-saving strategy step by step withhigher photosynthesis rate and lower transpiration rate. These physiological changes in the plants wereadaptable to the conditions of light, temperature and humidity in the habitat of the plants, and might be thebiological foundation for the geographical transition among C. microphylla , C. davazamcii and C. korshinskii.(2) The adaptation of photosynthetic system of C. microphylla , C. davazamcii and C. korshinskii to PAR, airhumidity and temperature exhibited the interspecific continuity, which was consistent with theenvironmental gradient. In different species and different sites, the diurnal changes of net photosynthesisrate, the daily cumulative value of net photosynthesis, the diurnal changes of transpiration rate, the dailycumulative value of transpiration, the water use efficiency and the diurnal changes of leaf water contentvaried with longitudinal descent (from the east to the west). The characteristics of photosynthesis andwater metabolism indicated that the geographical transition among C. microphylla , C. davazamcii and C.korshinskii was in gradual change, and these three species formed a geographical cline.
文摘Photosynthesis ( P n ), transpiration ( E ) and water use efficiency ( WUE ) of more than 66 arid sand species from different environmental habitats, shifting sand dune, fixed sand dune, lowland and wetland in the Maowusu Sand Area were analyzed and the relation among these characteristics and the resource utilization efficiency, taxonomic categories and growth forms of the species were assessed. The results showed that species from Chenopodiaceae, Gramineae, Leguminosae which possessed the C 4 photosynthesis pathway, or C 3 pathway and also with nitrogen_fixation capacities had higher or the highest P n values, i.e., 20～30 μmol CO 2·m -2 ·s -1 , while that of evergreen shrub of Pinaceae had the lowest P n values, i.e., 0～5 μmol CO 2·m -2 ·s -1 . Those species from Compositae, Scrophulariaceae, and Gramineae with C 3 pathway but no N_fixation capacity had the highest E rates, i.e., 20～30 mmol H 2O·m -2 ·s -1 and again the evergreen shrub together with some species from Salicaceae and Compositae had the lowest E rates, i.e., 0～5 mmol H 2O·m -2 ·s -1 . Species from Leguminosae, Gramineae and Chenopodiaceae with C 4 pathway or C 3 pathway with N_fixation capacity, both shrubs and grasses, generally had higher WUE . However, even the physiological traits of the same species were habitat_ and season_specific. The values of both P n and E in late summer were much higher than those in early summer, with average increases of 26%, 40% respectively in the four habitats. WUE in late summer was, however, 12% lower. Generally, when the environments became drier as a result of habitats changed, i.e., in the order of wetland, lowland, fixed sand dune and shifting sand dune, P n and E decreased but WUE increased.
文摘Transpiration element is included in the integrated stomatal conductance photosynthesis model by considering gaseous transfer processes, so the present model is capable to simulate the influence of boundary layer conductance. Leuning in his revised Ball's model replaced relative humidity with VPD s (the vapor pressure deficit from stomatal pore to leaf surface) and thereby made the relation with transpiration more straightforward, and made it possible for the regulation of transpiration and the influence of boundary layer conductance to be integrated into the combined model. If the differences in water vapor and CO 2 concentration between leaf and ambient air are considered, VPD s , the evaporative demand, is influenced by stomatal and boundary layer conductance. The physiological responses of photosynthesis, transpiration, and stomatal function, and the changes of intercellular CO 2 and water use efficiency to environmental factors, such as wind speed, photon flux density, leaf temperature and ambient CO 2, are analyzed. It is shown that if the boundary layer conductance drops to a level comparable with stomatal conductance, the results of simulation by the model presented here differ significantly from those by the previous model, and, in some cases, are more realistic than the latter.
文摘Four rice ( Oryza sativa L.) cultivars 'IR72', 'Tesanai 2', 'Guichao 2' and 'IIyou 4480' were grown in two plastic house (15 m×3 m) with 35 μmol/mol and 60 μmol/mol CO 2 concentration which was controlled by computer. As compared with rice at ambient 35 μmol/mol CO 2, the changes in photosynthetic rate at elevated CO 2 showed up_regulation ('IR72' and 'Tesanai 2'), stable (unchanged) in 'Guichao 2' and down_regulation type ('IIyou 4480'). Growth rate, panicle weight, integrated water use efficiency (WUE) calculated from Δ 13 C and the capacity of scavenging DPPH · (1,1_diphenyl_2_picrylhydrazyl) free radical were increased at elevated CO 2. An increment in total biomass was observed in three cultivars by elevated CO 2, with the exception of 'IIyou 4480'. Ratios of panicle weight/total biomass were altered to different extents in tested cultivars by elevated CO 2. When leaf segments were subjected to PEG osmotic stress, the electrolyte leakage rate from leaves grown at elevated CO 2 was less than that at 35 μmol/mol CO 2. Those intraspecific variations of rice imply a possibility for selecting cultivars with maximal productivity and high tolerance to stresses adapted to elevated CO 2 in the future.
基金Supported by National Natural Science Foundation of China(40765003)National Key Technology R &D Program in the 11th Five Year Plan of China (2007BAC03A02)~~
文摘[Objective] The aim was to study the effects of short-term high temperature stress on the photosynthesis of potato in different growth stages. [Method] Choosing powder potato named Longshu No.3 widely cultivated in Ningxia as test material,the changes of stomata conductance （Gs）,transpiration rate （Tr） and CO2 concentration difference between internal and external leaf chamber,net photosynthetic rate （Pn） and photosynthetic water use efficiency （WUE） in different growth stages under short-term high temperature were analyzed. [Result] During seedling stage,the hysteretic nature of net photosynthetic rate and CO2 concentration difference between internal and external leaf chamber of potato could be found under high temperature stress,while the change trends of stomata conductance and transpiration rate under high temperature stress were consistent to that at normal temperature,but stomata conductance and transpiration rate were higher than those at normal temperature,and CO2 concentration difference between internal and external leaf chamber affected net photosynthetic rate most obviously. During branching stage,the change trends of net photosynthetic rate,CO2 concentration difference between internal and external leaf chamber,stomata conductance and transpiration rate under high temperature stress and normal temperature were similar,but they changed abruptly and reached peak value at noon under high temperature stress,while there existed consistent variation of water use efficiency under high temperature stress and at normal temperature,and CO2 concentration difference between internal and external leaf chamber also affected net photosynthetic rate most greatly,next came transpiration rate. [Conclusion] High temperature stress affected the photosynthesis of potato in different growth stages,and it was more obvious during branching stage than seedling stage,while CO2 concentration difference between internal and external leaf chamber had the most important influence on net photosynthetic rate.
文摘Resurrection plants which are able to quickly reactivate after falling into a period of anabiosis caused by dehydration have been very rare among angiosperms, especially among dicotyledons whose chlorophyll content and chloroplast structure little changed in the course of desiccation, therefore has been called homoiochlorophyllous desiccation-tolerant plants (HDTs). Another type of resurrection angiosperms that lost its chlorophyll dining desiccation is called poikilochlorophyllous desiccation-tolerant plants (PDTs). HDTs have been received more attention because of simplicity of protection mechanism which is much easy to the study and utilization of the desiccation tolerance of resurrection angiosperms. Recent advances in studies of photosynthesis of resurrection angiosperms indicate that photochemical activities are sensitive indicators for the study of physiological state of resurrection angiosperms during desiccation and rehydration. Photochemical activities of resurrection angiosperms are inhibited with loss of water similar to those of general plants, however, the magic thing is that they could reactivate rapidly during rehydration even losing more than 95% water. Up-regulations in xanthophyll cycle and antioxidative systems as well as preservation in integrity and stability of photosynthetic membranes during desiccation may be very important to desiccation tolerance of resurrection angiosperms. The fact that phosphate treatment in rehydration stage also strongly influences resurrection indicated importance of studies on rehydration stages of resurrection angiosperms.
基金Suported by the Special Fund of China National Flue-Cured Tobacco Corporation for Development of Specifc and High-quality Tobbaco Leaf[110201101001(TS-01)]~~
文摘[Objective] This study aimed to test whether salicylic acid （SA） can im-prove the physiological functions of flue-cured tobacco under subdued light condition, and to determine the mechanism of its action. [Method] The tobacco plants under subdued light were foliar-sprayed with 100 mg/L of SA. Then, the physiological in-dices such as plant fresh weight and dry weight, chlorophyl content, photosynthetic parameters and chlorophyl fluorescence parameters were measured. SPSS17.0 and Excellwere adopted for variance analysis and significance test. [Result] The leaf photosynthetic rate （Pn）, stomatal conductance （Gs） and transpiration rate （Tr） of tobacco plants in subdued light were al decreased while the intercellular CO2 con-centration （Ci） was increased, suggesting that non-stomatal limitation led to the de-crease of Pn under weak light intensity stress. SA released the inhibition of tobacco plant growth in weak light, as it elevated the leaf photosynthetic rate, the maximum photochemical efficiency of PSⅡ, potential activity of PSⅡ, effective photochemical efficiency of PSⅡ and photochemical quenching coefficient in weak light significant-ly, and reduced the non-photochemical quenching coefficient. [Conclusion] SA has significant effects on the photosynthetic characteristics of flue-cured tobacco in weak light, and it can improve the synthesis or distribution of photosynthesis product, and the efficiency of light energy, conducive to plant growth and development.
