Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous pa- leoclimatic chan...Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous pa- leoclimatic changes prevailing in continental source areas.As one of the most important rivers input- ting terrigenous matters to the northern South China Sea,the Pearl River was not previously paid at- tention to from the viewpoint of clay mineralogy.This paper presents a detailed study on clay minerals in surface sediments collected from the Pearl River drainage basin(including all three main channels, various branches,and the Lingdingyang in the estuary)by using the X-ray diffraction(XRD)method. The results indicate that the clay mineral assemblage consists dominantly of kaolinite(35%-65%), lesser abundance of chlorite(20%-35%)and illite(12%-42%),and very scare smectite occurrences (generally<5%).Their respective distribution does not present any obvious difference throughout the Pearl River drainage basin.However,downstream the Pearl River to the northern South China Sea,the clay mineral assemblage varies significantly:kaolinite decreases gradually,smectite and illite increase gradually.Additionally,illite chemistry index steps down and illite crystallinity steps up.These varia- tions indicate the contribution of major kaolinite,lesser illite and chlorite,and very scarce smectite to the northern South China Sea from the Pearl River drainage basin.The maximum contribution of clay minerals from the Pearl River is 72%to the northern margin and only 15%to the northern slope of the South China Sea.In both glacials and interglacials,kaolinite indicates that the ability of mechanical erosion occurred in the Pearl River drainage basin.展开更多
A particle breakage has a significant impact on the mechanical behavior of granular materials. In this paper, we present an elasto-plastic model with two yield surfaces to which the influence of particle breakage has ...A particle breakage has a significant impact on the mechanical behavior of granular materials. In this paper, we present an elasto-plastic model with two yield surfaces to which the influence of particle breakage has been introduced. The main feature of this model is to incorporate the change in the critical state line (CSL) consequent to the grain breakage induced by isotropic and deviatoric stresses during loading. For this purpose we propose a breakage function which connects the evolution of the CSL to the energy consumed. Results from earlier studies on drained and undrained compression and extension triaxial tests were used to calibrate and validate the model. Comparison between earlier results and our simulations indicates that the model can reproduce with good accuracy the mechanical behavior of crushable granular materials and predict the evolution of the grain size distribution during loading.展开更多
Multimode fibers(MMFs)are an example of a highly scattering medium,which scramble the coherent light propagating within them to produce seemingly random patterns.Thus,for applications such as imaging and image project...Multimode fibers(MMFs)are an example of a highly scattering medium,which scramble the coherent light propagating within them to produce seemingly random patterns.Thus,for applications such as imaging and image projection through an MMF,careful measurements of the relationship between the inputs and outputs of the fiber are required.We show,as a proof of concept,that a deep neural network can learn the input-output relationship in a 0.75 m long MMF.Specifically,we demonstrate that a deep convolutional neural network(CNN)can learn the nonlinear relationships between the amplitude of the speckle pattern(phase information lost)obtained at the output of the fiber and the phase or the amplitude at the input of the fiber.Effectively,the network performs a nonlinear inversion task.We obtained image fidelities(correlations)as high as~98%for reconstruction and~94%for image projection in the MMF compared with the image recovered using the full knowledge of the system transmission characterized with the complex measured matrix.We further show that the network can be trained for transfer learning,i.e.,it can transmit images through the MMF,which belongs to another class not used for training/testing.展开更多
High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to recons...High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite+chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.展开更多
High-resolution clay mineralogical analysis of Core MD05-2904 in the northern South China Sea(SCS) covering the period since the Last Glacial Maximum shows that illite(29%-48%),smectite(14%-45%),chlorite(17%-28%),and ...High-resolution clay mineralogical analysis of Core MD05-2904 in the northern South China Sea(SCS) covering the period since the Last Glacial Maximum shows that illite(29%-48%),smectite(14%-45%),chlorite(17%-28%),and minor kaolinite(6%-14%) comprise the clay mineral assemblage,and that time series variation does not present glacial-interglacial cyclicity.Provenance analysis indicates three end-member sources:almost all smectite derives from Luzon,all kaolinite is sourced from the Pearl River,and illite and chlorite originate from both the Pearl River and Taiwan.By comparing clay mineral compositions in surface sediments from the three major source areas and of the SCS,we reconstructed a time series of clay mineral contribution from the major provenances to the northern slope of the SCS using the linear separation method for illite crystallinity.There were three stages of provenance change.(1) During 24.1-17.5 ka BP,contributions from Taiwan and Luzon were similar(30%-40%),while that from the Pearl River was only 25%.(2) During 17.5-14.0 ka BP,the contribution from Luzon decreased rapidly to 20%-25%,while that from Taiwan increased to 35% from an average of 25% at 18 ka BP,and that from the Pearl River increased largely to 40%.(3) During the Holocene,differences in contributions from the three major provenances increased:the contribution from Luzon increased slightly and then remained at 27%-35%,that from Taiwan increased rapidly and then remained at 55%-60%,and that from the Pearl River decreased to 15%.The change in clay mineral contributions from different provenances is influenced mainly by clay mineral production,monsoon rainfall denudation,oceanic current transport,and sea-level change.展开更多
The plant steroid hormones, brassinosteroids （BRs）, and their precursors, phytosterols, play major roles in plant growth, development, and stress tolerance. Here, we review the impressive progress made during recent...The plant steroid hormones, brassinosteroids （BRs）, and their precursors, phytosterols, play major roles in plant growth, development, and stress tolerance. Here, we review the impressive progress made during recent years in elucidating the components of the sterol and BR metabolic and signaling pathways, and in understanding their mecha- nism of action in both model plants and crops, such as Arabidopsis and rice. We also discuss emerging insights into the regulations of these pathways, their interactions with other hormonal pathways and multiple environmental signals, and the putative nature of sterols as signaling molecules.展开更多
Aims In perennial species,the allocation of resources to reproduction results in a reduction of allocation to vegetative growth and,therefore,impacts future reproductive success.As a consequence,variation in this trad...Aims In perennial species,the allocation of resources to reproduction results in a reduction of allocation to vegetative growth and,therefore,impacts future reproductive success.As a consequence,variation in this trade-off is among the most important driving forces in the life-history evolution of perennial plants and can lead to locally adapted genotypes.In addition to genetic variation,phenotypic plasticity might also contribute to local adaptation of plants to local conditions by mediating changes in reproductive allocation.Knowledge on the importance of genetic and environmental effects on the tradeoff between reproduction and vegetative growth is therefore essential to understand how plants may respond to environmental changes.Methods We conducted a transplant experiment along an altitudinal gradient from 425to1921 min the frontrange of the Western Alps of Switzerland to assess the influence of both altitudinal origin of populations and altitude of growing site on growth,reproductive investment and local adaptation in Poa alpina.Important findings In our study,the investment in reproduction increased with plant size.Plant growth and the relative importance of reproductive investment decreased in populations originating from higher altitudes compared to populations originating from lower altitudes.The changes in reproductive investment were mainly explained by differences in plant size.In contrast to genetic effects,phenotypic plasticity of all traits measured was low and not related to altitude.As a result,the population from the lowest altitude of origin performed best at all sites.Our results indicate that in P.alpina genetic differences in growth and reproductive investment are related to local conditions affecting growth,i.e.interspecific competition and soil moisture content.展开更多
Reactive Oxygen Species （ROS） are continuously produced as a result of aerobic metabolism or in response to biotic and abiotic stresses. ROS are not only toxic by-products of aerobic metabolism, but are also signall...Reactive Oxygen Species （ROS） are continuously produced as a result of aerobic metabolism or in response to biotic and abiotic stresses. ROS are not only toxic by-products of aerobic metabolism, but are also signalling molecules involved in several developmental processes in all organisms. Previous studies have clearly shown that an oxidative burst often takes place at the site of attempted invasion during the early stages of most plant-pathogen interac- tions. Moreover, a second ROS production can be observed during certain types of plant-pathogen interactions, which triggers hyper- sensitive cell death （HR）. This second ROS wave seems absent during symbiotic interactions. This difference between these two responses is thought to play an important signalling role leading to the establishment of plant defense. In order to cope with the deleterious effects of ROS, plants are fitted with a large panel of enzymatic and non-enzymatic antioxidant mechanisms. Thus,increasing numbers of publications report the characterisation of ROS producing and scavenging systems from plants and from microorganisms during interactions. In this review, we present the current knowledge on the ROS signals and their role during plant-microorganism interactions.展开更多
Recent advances in the proteomic field have allowed high-throughput experiments to be conducted on chloroplast samples. Many proteomic investigations have focused on either whole chloroplast or sub-plastidial fraction...Recent advances in the proteomic field have allowed high-throughput experiments to be conducted on chloroplast samples. Many proteomic investigations have focused on either whole chloroplast or sub-plastidial fractions. To date, the Plant Protein Database （PPDB, Sun et al., 2009） presents the most exhaustive chloroplast proteome available online. However, the accurate localization of many proteins that were identified in different sub-plastidial compartments remains hypothetical. Ferro et al. （2009） went a step further into the knowledge of Arabidopsis thaliana chloroplast proteins with regards to their accurate localization within the chloroplast by using a semi-quantitative proteomic approach known as spectral counting. Their proteomic strategy was based on the accurate mass and time tags （AMT） database approach and they built up AT_CHLORO, a comprehensive chloroplast proteome database with sub-plastidial localization and curated information on envelope proteins. Comparing these two extensive databases, we focus here on about 100 enzymes involved in the synthesis of chloroplast-specific isoprenoids. Well known pathways （i.e. compartmentation of the methyl erythritol phosphate biosynthetic pathway, of tetrapyrroles and chlorophyll biosynthesis and breakdown within chloroplasts） validate the spectral counting-based strategy. The same strategy was then used to identify the precise localization of the biosynthesis of carotenoids and prenylquinones within chloroplasts （i.e. in envelope membranes, stroma, and/or thylakoids） that remains unclear until now.展开更多
Insufficient dietary intake of micronutHents, known as ＂hidden hunger＂, is a devastating global burden, affecting two billion people. Deficiency of folates （vitamin B9）, which are known to play a central role in C...Insufficient dietary intake of micronutHents, known as ＂hidden hunger＂, is a devastating global burden, affecting two billion people. Deficiency of folates （vitamin B9）, which are known to play a central role in Cl metabolism, causes birth defects in at least a quarter million people annually. Biofortification to enhance the level of naturally occurring folates in crop plants, proves to be an efficient and cost-effective tool in fighting folate deficiency. Previously, introduction of folate biosynthesis genes GTPCHI andADCS, proven to be a successful biofortification strategy in rice and tomato, turned out to be insufficient to adequately increase folate levels in potato tubers. Here, we provide a proof of concept that additional introduction of HPPK/DHPS and/or FPGS, downstream genes in mitochonddal folate biosynthesis, enables augmenta- tion of folates to satisfactory levels （12-fold） and ensures folate stability upon long-term storage of tubers. In conclusion, this engineering strategy can serve as a model in the creation of folate-accumulating potato cultivars, readily applicable in potato-consuming populations suffedng from folate deficiency.展开更多
Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the prese...Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the present study, laboratory batch experiment of metal solubilization, cress seeds germination were undertaken to investigate the metal-mobilizing capability and the phytotoxicity of organic additives, including ethylene diamine triacetic acid （EDTA）, citric acid, acetic acid, oxalic acid, glutamine and monosodium glutamate waste liquid （MGWL） from food industry. Experiments in pots were carried out to study the effects of the additives on Zn and Cd phytoextraction. Furthermore, a leaching experiment with lysimeter was performed to evaluate the environmental risks of additive-induced leaching to underground water. The results showed that EDTA had a strong mobilizing ability for Zn and Cd, followed by mixed reagent （MR） and MGWL. MGWL and acetic acid at 5 mmol equivalent per liter resulted in seed germination index less than 2%. Experiments in pots verified the phytotoxicity of acetic acid and MGWL. Addition of the mixed reagent at 6--10 mmol/kg significantly increased Zn phytoextraction by Thlaspi caerulescens. The same for EDTA and the mixed reagent at 10 mmol/kg by Sedum dfredii. But only mixed reagents could significantly increase Cd phytoextraction by the studied hyperaccumulators. This suggested that the strong chelant was not always the good agent to enhance phytoextraction. S. alfredii combined with 2--10 mmol/kg soil MR was preferred for phytoremediation of Cd/Zn contaminated soils in southern China, this could result in high phytoextraction of Cd/Zn and reduce the leaching risk to underground water than EDTA assisted phytoextration.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.40331002,40621063 and 40506014)the Fok Ying Tung Education Foundation(Grant No.101018)+2 种基金the Doctoral Program of Higher Education(Grant No.20060247032)the Excellent Young Teachers Program and the Program for New Century Excellent Talents in University of the Ministry of Education of China(GrantNo.NCET-04-0372)and the Laboratory of Marginal Sea Geology Grant of theChinese Academy of Sciences(Grant No.BYH03A08)
文摘Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous pa- leoclimatic changes prevailing in continental source areas.As one of the most important rivers input- ting terrigenous matters to the northern South China Sea,the Pearl River was not previously paid at- tention to from the viewpoint of clay mineralogy.This paper presents a detailed study on clay minerals in surface sediments collected from the Pearl River drainage basin(including all three main channels, various branches,and the Lingdingyang in the estuary)by using the X-ray diffraction(XRD)method. The results indicate that the clay mineral assemblage consists dominantly of kaolinite(35%-65%), lesser abundance of chlorite(20%-35%)and illite(12%-42%),and very scare smectite occurrences (generally<5%).Their respective distribution does not present any obvious difference throughout the Pearl River drainage basin.However,downstream the Pearl River to the northern South China Sea,the clay mineral assemblage varies significantly:kaolinite decreases gradually,smectite and illite increase gradually.Additionally,illite chemistry index steps down and illite crystallinity steps up.These varia- tions indicate the contribution of major kaolinite,lesser illite and chlorite,and very scarce smectite to the northern South China Sea from the Pearl River drainage basin.The maximum contribution of clay minerals from the Pearl River is 72%to the northern margin and only 15%to the northern slope of the South China Sea.In both glacials and interglacials,kaolinite indicates that the ability of mechanical erosion occurred in the Pearl River drainage basin.
文摘A particle breakage has a significant impact on the mechanical behavior of granular materials. In this paper, we present an elasto-plastic model with two yield surfaces to which the influence of particle breakage has been introduced. The main feature of this model is to incorporate the change in the critical state line (CSL) consequent to the grain breakage induced by isotropic and deviatoric stresses during loading. For this purpose we propose a breakage function which connects the evolution of the CSL to the energy consumed. Results from earlier studies on drained and undrained compression and extension triaxial tests were used to calibrate and validate the model. Comparison between earlier results and our simulations indicates that the model can reproduce with good accuracy the mechanical behavior of crushable granular materials and predict the evolution of the grain size distribution during loading.
基金funding from the Swiss National Science Foundation(SNSF)project MuxWave(200021_160113/1)funded by CERAMIC X.0—High-precision micromanufacturing of ceramics(ID:14032).
文摘Multimode fibers(MMFs)are an example of a highly scattering medium,which scramble the coherent light propagating within them to produce seemingly random patterns.Thus,for applications such as imaging and image projection through an MMF,careful measurements of the relationship between the inputs and outputs of the fiber are required.We show,as a proof of concept,that a deep neural network can learn the input-output relationship in a 0.75 m long MMF.Specifically,we demonstrate that a deep convolutional neural network(CNN)can learn the nonlinear relationships between the amplitude of the speckle pattern(phase information lost)obtained at the output of the fiber and the phase or the amplitude at the input of the fiber.Effectively,the network performs a nonlinear inversion task.We obtained image fidelities(correlations)as high as~98%for reconstruction and~94%for image projection in the MMF compared with the image recovered using the full knowledge of the system transmission characterized with the complex measured matrix.We further show that the network can be trained for transfer learning,i.e.,it can transmit images through the MMF,which belongs to another class not used for training/testing.
基金Supported by the National Key Basic Research Special Foundation Project of China (Grant No. 2007CB815906)the National Natural Science Foundation of China (Grant Nos. 40321603 and 40331002)+3 种基金the Fok Ying Tung Education Foundation (Grant No. 101018)the Doctoral Program of Higher Education (Grant No. 20060247032)the Sino-Netherlands Science Cooperation Project (Grant No. 2004CB720506)the Program for New Century Excellent Talents in University of the Ministry of Education of China (Grant No. NCET-04-0372)
文摘High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite+chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.
基金supported by the National Natural Science Foundation of China (40925008,40876024 and 40776027)the National Basic Research Program of China (2007CB815906)+1 种基金the Shanghai Shuguang Program (07SG23)the Shanghai Subject Chief Scientist Program (10XD1406300)
文摘High-resolution clay mineralogical analysis of Core MD05-2904 in the northern South China Sea(SCS) covering the period since the Last Glacial Maximum shows that illite(29%-48%),smectite(14%-45%),chlorite(17%-28%),and minor kaolinite(6%-14%) comprise the clay mineral assemblage,and that time series variation does not present glacial-interglacial cyclicity.Provenance analysis indicates three end-member sources:almost all smectite derives from Luzon,all kaolinite is sourced from the Pearl River,and illite and chlorite originate from both the Pearl River and Taiwan.By comparing clay mineral compositions in surface sediments from the three major source areas and of the SCS,we reconstructed a time series of clay mineral contribution from the major provenances to the northern slope of the SCS using the linear separation method for illite crystallinity.There were three stages of provenance change.(1) During 24.1-17.5 ka BP,contributions from Taiwan and Luzon were similar(30%-40%),while that from the Pearl River was only 25%.(2) During 17.5-14.0 ka BP,the contribution from Luzon decreased rapidly to 20%-25%,while that from Taiwan increased to 35% from an average of 25% at 18 ka BP,and that from the Pearl River increased largely to 40%.(3) During the Holocene,differences in contributions from the three major provenances increased:the contribution from Luzon increased slightly and then remained at 27%-35%,that from Taiwan increased rapidly and then remained at 55%-60%,and that from the Pearl River decreased to 15%.The change in clay mineral contributions from different provenances is influenced mainly by clay mineral production,monsoon rainfall denudation,oceanic current transport,and sea-level change.
文摘The plant steroid hormones, brassinosteroids （BRs）, and their precursors, phytosterols, play major roles in plant growth, development, and stress tolerance. Here, we review the impressive progress made during recent years in elucidating the components of the sterol and BR metabolic and signaling pathways, and in understanding their mecha- nism of action in both model plants and crops, such as Arabidopsis and rice. We also discuss emerging insights into the regulations of these pathways, their interactions with other hormonal pathways and multiple environmental signals, and the putative nature of sterols as signaling molecules.
基金Swiss National Science Foundation(grant 110000 to A.G.)the European Commission(FP6 projects MACIS and ECOCHANGE).
文摘Aims In perennial species,the allocation of resources to reproduction results in a reduction of allocation to vegetative growth and,therefore,impacts future reproductive success.As a consequence,variation in this trade-off is among the most important driving forces in the life-history evolution of perennial plants and can lead to locally adapted genotypes.In addition to genetic variation,phenotypic plasticity might also contribute to local adaptation of plants to local conditions by mediating changes in reproductive allocation.Knowledge on the importance of genetic and environmental effects on the tradeoff between reproduction and vegetative growth is therefore essential to understand how plants may respond to environmental changes.Methods We conducted a transplant experiment along an altitudinal gradient from 425to1921 min the frontrange of the Western Alps of Switzerland to assess the influence of both altitudinal origin of populations and altitude of growing site on growth,reproductive investment and local adaptation in Poa alpina.Important findings In our study,the investment in reproduction increased with plant size.Plant growth and the relative importance of reproductive investment decreased in populations originating from higher altitudes compared to populations originating from lower altitudes.The changes in reproductive investment were mainly explained by differences in plant size.In contrast to genetic effects,phenotypic plasticity of all traits measured was low and not related to altitude.As a result,the population from the lowest altitude of origin performed best at all sites.Our results indicate that in P.alpina genetic differences in growth and reproductive investment are related to local conditions affecting growth,i.e.interspecific competition and soil moisture content.
文摘Reactive Oxygen Species （ROS） are continuously produced as a result of aerobic metabolism or in response to biotic and abiotic stresses. ROS are not only toxic by-products of aerobic metabolism, but are also signalling molecules involved in several developmental processes in all organisms. Previous studies have clearly shown that an oxidative burst often takes place at the site of attempted invasion during the early stages of most plant-pathogen interac- tions. Moreover, a second ROS production can be observed during certain types of plant-pathogen interactions, which triggers hyper- sensitive cell death （HR）. This second ROS wave seems absent during symbiotic interactions. This difference between these two responses is thought to play an important signalling role leading to the establishment of plant defense. In order to cope with the deleterious effects of ROS, plants are fitted with a large panel of enzymatic and non-enzymatic antioxidant mechanisms. Thus,increasing numbers of publications report the characterisation of ROS producing and scavenging systems from plants and from microorganisms during interactions. In this review, we present the current knowledge on the ROS signals and their role during plant-microorganism interactions.
文摘Recent advances in the proteomic field have allowed high-throughput experiments to be conducted on chloroplast samples. Many proteomic investigations have focused on either whole chloroplast or sub-plastidial fractions. To date, the Plant Protein Database （PPDB, Sun et al., 2009） presents the most exhaustive chloroplast proteome available online. However, the accurate localization of many proteins that were identified in different sub-plastidial compartments remains hypothetical. Ferro et al. （2009） went a step further into the knowledge of Arabidopsis thaliana chloroplast proteins with regards to their accurate localization within the chloroplast by using a semi-quantitative proteomic approach known as spectral counting. Their proteomic strategy was based on the accurate mass and time tags （AMT） database approach and they built up AT_CHLORO, a comprehensive chloroplast proteome database with sub-plastidial localization and curated information on envelope proteins. Comparing these two extensive databases, we focus here on about 100 enzymes involved in the synthesis of chloroplast-specific isoprenoids. Well known pathways （i.e. compartmentation of the methyl erythritol phosphate biosynthetic pathway, of tetrapyrroles and chlorophyll biosynthesis and breakdown within chloroplasts） validate the spectral counting-based strategy. The same strategy was then used to identify the precise localization of the biosynthesis of carotenoids and prenylquinones within chloroplasts （i.e. in envelope membranes, stroma, and/or thylakoids） that remains unclear until now.
文摘Insufficient dietary intake of micronutHents, known as ＂hidden hunger＂, is a devastating global burden, affecting two billion people. Deficiency of folates （vitamin B9）, which are known to play a central role in Cl metabolism, causes birth defects in at least a quarter million people annually. Biofortification to enhance the level of naturally occurring folates in crop plants, proves to be an efficient and cost-effective tool in fighting folate deficiency. Previously, introduction of folate biosynthesis genes GTPCHI andADCS, proven to be a successful biofortification strategy in rice and tomato, turned out to be insufficient to adequately increase folate levels in potato tubers. Here, we provide a proof of concept that additional introduction of HPPK/DHPS and/or FPGS, downstream genes in mitochonddal folate biosynthesis, enables augmenta- tion of folates to satisfactory levels （12-fold） and ensures folate stability upon long-term storage of tubers. In conclusion, this engineering strategy can serve as a model in the creation of folate-accumulating potato cultivars, readily applicable in potato-consuming populations suffedng from folate deficiency.
基金The Hi-Tech Research and Development Program (863) of China (No. 2001-AA-640501-3)French-Chinese Programme deRecherche Avancee (No. PRA E-03-02) the National Natural Science Foundation of China (No. 40571141)
文摘Chelant-enhanced phytoextraction is one of the most promising technologies to remove heavy metals from soil. The key of the technology is to choose suitable additives in combination with a suitable plant. In the present study, laboratory batch experiment of metal solubilization, cress seeds germination were undertaken to investigate the metal-mobilizing capability and the phytotoxicity of organic additives, including ethylene diamine triacetic acid （EDTA）, citric acid, acetic acid, oxalic acid, glutamine and monosodium glutamate waste liquid （MGWL） from food industry. Experiments in pots were carried out to study the effects of the additives on Zn and Cd phytoextraction. Furthermore, a leaching experiment with lysimeter was performed to evaluate the environmental risks of additive-induced leaching to underground water. The results showed that EDTA had a strong mobilizing ability for Zn and Cd, followed by mixed reagent （MR） and MGWL. MGWL and acetic acid at 5 mmol equivalent per liter resulted in seed germination index less than 2%. Experiments in pots verified the phytotoxicity of acetic acid and MGWL. Addition of the mixed reagent at 6--10 mmol/kg significantly increased Zn phytoextraction by Thlaspi caerulescens. The same for EDTA and the mixed reagent at 10 mmol/kg by Sedum dfredii. But only mixed reagents could significantly increase Cd phytoextraction by the studied hyperaccumulators. This suggested that the strong chelant was not always the good agent to enhance phytoextraction. S. alfredii combined with 2--10 mmol/kg soil MR was preferred for phytoremediation of Cd/Zn contaminated soils in southern China, this could result in high phytoextraction of Cd/Zn and reduce the leaching risk to underground water than EDTA assisted phytoextration.
