Abstract:A shoot-specific promoter was isolated in maize inbred line‘Zong 31’and was named as ZmSSP.By changing the CaMV35S promoter in pCAMBIA3301 into ZmSSP,a new plant expression vector pCAMBIA3301-ZmSSP-GUS was constructed,in which the reporter gene GUS was driven by ZmSSP.By Agrobacterium tumefaciens mediated method,transgenic tobacco lines were obtained,in which reporter gene GUS expression patterns were analyzed.The results showed that ZmSSP had lower promoter activity than CaMV35S,and its pattern was quite different in different transgenic lines.Statistical data of 10 transgenic lines showed that the highest GUS expression level in tobacco appeared in petiole (2.71 times higher than that of Actin),and the following was in leaf and shoot.In root,very low GUS expression level was detected,which was 29.6 percent of that of Actin,and 10.9 percent of itself in petioles.The results indicate that ZmSSP is a good tissue-specific promoter in plant genetic engineering,suitable for trait improvement of underground vegetative organs.

Abstract:In order to study the enzymatic activity of Arabidopsis poly(ADP-ribose) polymerase 1(PARP1),the cDNA fragment of PARP1 was amplified using Reverse-Transcription PCR method from Arabidopsis seedlings treated by bleomycin.The cDNA sequence was cloned into prokaryotic expression vector pET32 and the resultant pET32a-PARP1 plasmid was transformed into Escherichia coli host strain Origami(DE3).IPTG was added into the culture to a final concentration of 0.3 mmol/L to induce expression at 16 ℃ for 20 h.The recombinant protein TRX-PARP1 was purified and then assayed for enzymatic activity with the substrate NAD⁺ and broken DNA in the reaction buffer.TRX-PARP1 protein band shifted upwardly in a time course on SDS-PAGE gel.Western blotting using anti-PARP1 antibody further confirmed that the molecular mass of TRX-PARP1 increased gradually,due to the linkage of ADP ribose molecules onto the protein.In contrast,the fusion tag protein Thioredoxin(TRX) did not show any change in mobility.These data demonstrated that Arabidopsis PARP1 produced in E.coli has auto-modification activity,which facilitates the functional study of PARP1 in Arabidopsis.

Abstract:The full length ORF of AtPUB18 was cloned from Arabidopsis thaliana by RT-PCR.Informatic analysis manifested that AtPUB18 shared similarity of 74.9% and identity of 63.5% with AtPUB19 using VectorNTI and MEGA5.0;A 1 974 bp promoter fragment of AtPUB18 was fused with GUS gene to generate transgenic A.thaliana.The expression level of AtPUB18 was elevated after drought and cold treatment by histochemical GUS assay.AtPUB18 was fused with green fluorescent protein(GFP) gene to generate a transient expression vector.AtPUB18-GFP fusion protein was expressed in A.thaliana protoplasts and observed using confocal microscope.The result showed that AtPUB18-GFP fusion protein distributed in nucleus and cytosol;AtPUB18 was fused with maltose binding protein(MBP) gene to generated AtPUB18-MBP fusion protein in E.coli for ubiquitin ligase activity assay.The result indicated that AtPUB18 had ubiquitin ligase activity with the presence of wheat E1 and human E2.Our studies implied that AtPUB18 was a functional E3 ligase and localized in nucleus and cytosol,and might be involved in the response to abiotic stress in A.thaliana.

Abstract:In Arabidopsis,we screened and isolated a mutant asm1 (ABA sensitive mutant 1,asm1) in the T-DNA mutant library,on ABA medium asm1 was more sensitive to ABA than the wild type on root elongation,further study showed on seed germination asm1 germinated earlier than WT.In terms of growth and development,asm1 exhibited early-flowering and dwarf phenotypes,the size of siliques of the mutants was shorter and more stunted compared with the wild type.Using far infrared imaging system we found that the leaf temperature of asm1 mutant was higher than the wild type under drought stress,water loss rate of mutant was lower and water loss was reduced.Genetic analysis revealed asm1 was a single recessive-gene mutant and cosegregated with a T-DNA tag,We used map-based cloning to identify the candidate gene ASM1.RT-PCR results showed that in the mutant the expression of ASM1 was inhibited,and could regulate expression levels of a variety of ABA signaling and stress response genes.These results indicate that ASM1 may be involved in the regulation of ABA signal transduction and response to drought stress.

Abstract:In this study,the cucumber seedlings were infected by Pseudoperonospora cubensis,and the gene of hypersensitive induced reaction proteins (CsHIR1) was cloned.The prokaryotic expression vector of pET28a-CsHIR1 was constructed and efficiently expressed in E.coli BL21(DE3).The induced expression duration and the concentration of IPTG were optimized.The recombinant protein was purified by cobalt chelating chromatography to prepare the high titer polyclonal antiserum.The results showed that CsHIR1 were expressed in the form of inclusion body,and the optimal induction duration and IPTG concentration were 4 h and 0.5 mmol·L^-1,respectively.High purity recombinant protein CsHIR1 with molecular weight 34 kD was obtained.Western blotting results showed that the antibody of CsHIR1 has good specificity.The prokaryotic expression system establishment and polyclonal antibodies preparation lay the foundation for further investigating the function of the CsHIR1 gene in cucumber.

Abstract:In this study,the tissue culture seedlings of Vaccinium uliginosum Linn.were used as material,the EMS mutation system has been established,the alkali-resistance mutants were screened by using EMS and NaHCO₃ combinative stress method,and identified with some physiological indexes.The results showed that:(1)0.4% EMS immersion the stem 4 h was the suitable mutation concentration,survival rate could reach 46.7%;when 0.1% EMS was applied into the medium 3 days,survival rate could reach 50%;the suitable concentration of NaHCO₃ was 8 mmol·L^-1,after three times alternating culture,two candidate mutants have been screened;(2)Identification of physiological index showed the activities of SOD,POD and proline content which significantly higher than those in control,the content of MDA which significantly lower than those in control.The study showed the mutants have some ability in weak alkali-tolerance.

Abstract:In the present study,a population of 236 RIL(F7 and F8 generation) derived from two elite Chinese wheat (Triticum aestivum L.) cultivars ‘Xiaoyan 81’ and ‘Xinong 1376’,were used in an experimental study in Yangling of Shaanxi Province,Zhumadian of Henan Province and Jinan of Shandong Province for two consecutive years.The genetic linkage map was constructed with 172 SSR markers and the additive QTLs for the flag leaf length,width and area in wheat were analyzed through the software QTL IciMapping V3.2 which is based on the inclusive composite interval mapping.The results showed that:(1)9 QTLs for flag leaf length were located on chromosomes 1A,4A,3B,5D and 7D,single QTL explaining 5.10%~16.44% of the phenotypic variances.10 QTLs were located on chromosomes 1A,3A,5A,7A,3B and 5D,detected for flag leaf width,single QTL explaining the phenotypic variations from 4.63%~14.24%.12 QTLs for flag leaf area were mapped on 1A,4A,3B,2D and 5D chromosomes,accounting for 4.25%~22.67% of the phenotypic variations.(2)QTLs for flag leaf length,width and area were different and the genetic contribution of the same QTL were also variant in different phenotypic traits.(3)Among the QTLs for the same trait in the same year in different locations and those in the different years in the same location,some were the same but the others were different.(4)Some QTLs for different traits were located at the same marker interval of a chromosome and they performed pleiotropy.The results suggested that 2 QTLs detected on chromosomes 1A and 5D controlled the flag leaf length,width and area in wheat together.Besides,the former was the main effect gene and the phenotypic variation of latter was significant so that they could be used in marker-assisted selection breeding and polymerization breeding.

Abstract:Isatis violascens Bunge is a spring ephemeral plant occurred in the sandy deserts of Junggar (or Dzungaria) Basin.It was suggested as a synonym of Isatis emarginata based on their morphology similarity.I.violascens has not been included in any molecular studies to date and its phylogenetic relationship is unknown.In present study,the nuclear ribosomal internal transcribed spacer(ITS) of I.violascens was sequenced.27 samples representing 18 Isatis species were analyzed using most parsimony,most likelihood and Bayesian method.Two well supported clades of Isatis were confirmed.I.violascens was closely related with I.emarginata and I.minima.From the evidence of similarities of morphology and low distance of ITS sequences,we provisionally agree with the merge of the two species and the reduction of I.violascens to synonym of I.emarginata.

Abstract:Based on analyzed zymograms of leaf peroxidase isozyme (POD),superoxide dismutase (SOD) and bud esterase (EST) by polyacrylamide gel electrophoresis (PAGE),we studied the genetic diversity of 32 Capsicum genus germplasms.The results showed that:(1)A total of 29 kinds of bands were produced,including 13 kinds of 234 POD bands,the proportion of polymorphic loci (PPL) and the range of relative mobility (Rf) were 50.0%~80.0% and 0.05~0.69;8 kinds of 140 SOD bands,PPL was 100.0%,and Rf was 0.38~0.88;8 kinds of 163 EST bands,PPL was 50.0%~87.5%,and Rf was 0.16~0.89.(2)26 polymorphic loci were found,and PPL,total gene frequency (P_t),mean number of alleles (A),Nei’s genetic diversity index (H_e),Shannon’s information index (SII),average of genetic identity (GI) and genetic distance (GD) were 89.66%,0.578 7,1.896 6,0.272 2,0.415 2,0.736 6 and 0.314 3,respectively;Jaccard genetic similarity coefficients were in range of 0.348~0.905,by which 32 materials were clustered into 4 cultivated populations/species.(3)Genetic diversity within species (H_S) of 4 cultivated species was 0.143 6,and genetic diversity among species (D_ST),gene differentiation coefficients among species (G_ST),GI and GD were 0.149 4,0.51,0.784 4 and 0.246 6,respectively.(4)In 9 purple germplasms,16 polymorphic loci were found,and PPL,P_t,A,H_e,SII,GI and GD were 55.17%,0.611 1,1.551 7,0.194 1,0.291 9,0.781 6 and 0.249 4,respectively.In conclusion,high genetic differentiation degree among overall tested materials,or among cultivated species and within species,or among purple materials will provide a reference to selecting parents of purple capsicum crossbreeding and genetic improvement of the green variety.

Abstract:Ultrastructural features during endosperm development of Plantago major L.were viewed and described by means of transmission electron microscope(TEM).The results are as follows:(1)Cellular type endosperm.The primary endosperm nucleus divides into a micropylar and chalazal chamber.The micropylar chamber becomes 8-celled in two tiers by two vertical and a transverse divisions.The four cells in the micropylar tier develop into four micropylar haustoria.The lower four cells develop into endosperm propers.The chalazal chamber develops into a binucleate haustorium by mitosis without division of cytoplasm.(2)The tubular micropylar haustorium penetrates into integument and its micropylar wall has a large amount of ingrowths and a few branches.There are a lot of mitochondria,rough endoplasmic reticulum,golgi bodies and plastids etc.around the ingrowths.The nucleus and nucleolus are obvious and the cytoplasm is dense.The metabolism is exuberant.During the period of global embryo,the micropylar haustorium shows the maximum size and integument around micropylar haustorium is hydrolyzed and resulted in a cavity.Micropylar haustorium absorbs and transforms nutrition from integument to endosperm proper to engage in forming endosperm proper and storing nutrition.At the later stage of global embryo,the micropylar haustorium degenerates gradually.(3)The four original cells of endosperm proper have vigorous meristematic ability,and divide anticlinally and periclinally.The endosperm proper surrounding the embryo is spherical-shaped.The nutrition absorbed by the haustorium and integument tapetum is stored in the endosperm proper.With degeneration of the suspensor,the endosperm proper is hydrolyzed in the period of later global embryo.(3)The two nuclei and nucleoli of chalazal haustorium are large.Mitochondria,plastids,golgi bodies and rough endoplasmic reticulum are located around the nucleus.Chalazal haustorium becomes high vacuolated.Along with the embryo and endosperm proper increasing in size,chalazal haustorium expends towards the chalazal end of the ovule while the chalaza surrounding the chalazal haustorium is hydrolyzed gradually,resulting in a cavity.Chalazal haustorium absorbs and transforms nutrition to the endosperm proper to engage in forming endosperm proper and storing nutrition.During the later period of global embryo,the chalazal haustorium loses its function and degenerates gradually.

Abstract:Polypodiaceae is the most evolutionary group in the ferns.However,the egg development in this group is less studied.The present investigation chooses the fern Phymatosorus hainanensis of Polypodiaceae,to examine the detailed development of the egg.Ultrastructural observations indicate that:(1)The young egg,the ventral canal cell and neck canal cell are closely connected with each other by plasmadesmata.(2)During egg development,the cell wall above the egg become obvious thickened and then a separation cavity,which contains plenty of amorphous materials,is formed beneath the wall.(3)A connection region persistently connects the egg and the ventral canal cell in the central area of the upper surface of the egg.(4)An egg envelope is formed by deposition of amorphous materials in the separation cavity on the outer surface of the plasmalemma.The egg envelope was not formed across the connection region;instead,a fertilization pore was formed.(5)In the later stage of oogenesis,the egg nucleus becomes irregular in outline and produces extensive evaginations.The present investigation provides new data on oogenesis of the ferns,which contributes to understanding of the cytological mechanism of the sexual reproduction of ferns and their evolution.

Abstract:We studied on the anatomical characteristics of roots with different orders of Salix gordejevii by paraffin and hand-sliced methods,and defined its fine root combining with the diameters and root orders.The results showed that:(1)The first and the second order roots had only primary growth.The fourth and the fifth order roots had secondary growth.Some of the third order roots had primary growth,but some had secondary growth.(2)The primary xylem was triarch or tetrarch.(3)There were significant differences in root morphology and anatomy of different orders of S.gordejevii.With the increase of the root order,the diameters of roots and vascular cylinder increased.The diameters of lower roots were mainly influenced by vascular cylinder diameters,the diameters of cortical parenchyma cells and cortical layers,and the diameters of senior roots were mainly affected by vascular cylinder diameters.(4)We defined the fine roots of S.gordejevii that should do not form successive phellogen among the first and the third root orders and have diameters less than 0.7 mm.The anatomical characteristics and fine root of roots among different orders of S.gordejevii were determined.The research was provided a reference for the studies on the fine roots and the carbon allocation of psammophyte.The method we used was important to accurately estimate the function of fine roots in the ecosystem.

Abstract:The development and the structures of the annual and the perennial tap roots of Platycodon grandiflorum were studied with the paraffin section and the semi-thin section.The results showed that the development of P.grandiflorum root could be divided into four stages:promeristem,primary meristem,primary growth and secondary growth.The promeristem consists of three groups of initial cells;the primary meristem is composed of calyptrogens,primordial epidermis,periblem and plerome.The primary structure includes epidermis,cortex and stele.Parenchyma cells in cortex are dominant.The primary xylem is diarch.The secondary growth depends on activities of the vascular cambium and the cork cambium.The secondary structure includes periderm and secondary vascular tissue from the outside to the inside.Parenchyma cells are prominent in the secondary vascular tissue,and only small amount of vascular elements are scattered in them.The perennial roots have the similar structure to the annual one,but there are some differences in the length and the diameter of the tap root,the thickness of periderm and the area ratio between the xylem and the phloem.

Abstract:To understand whether methanol- or ethanol-promoted plant growth is related to the synthesis of gibberellin (GA),we investigated the effects of exogenous GA and paclobutrazol(PAC),an inhibitor of GA synthesis,on 2 mmol/L methanol- and ethanol-stimulated growth of tobacco on MS agar medium and analyzed the molecular mechanism of RSG,the GA synthesis-regulated transcription factor,in response to methanol- and ethanol-stimulation in tobacco.The results showed that:(1)The addition of exogenous GA enhanced the stimulation of methanol and ethanol on tobacco growth while addition of PAC inhibited their stimulation to tobacco growth.(2)The binding of 14-3-3 proteins with RSG inhibits RSG transport into nucleus and reduced its transcriptional regulatory activity.Methanol and ethanol induced transcription and expression of 14-3-3 genes as well as RSG protein expression.(3)Methanol and ethanol reduced the interaction of 14-3-3 proteins and RSG while enhanced the binding of RSG to GA20ox1 promoter.These results indicated that methanol- and ethanol-stimulated tobacco growth might be achieved through increasing nuclear localization of RSG by inducing RSG expression and simultaneously reducing the interaction of RSG with 14-3-3 proteins.Consequently,the binding of RSG and GA20ox1 promoter was enhanced and GA protein synthesis increased,thereby promoting the growth of tobacco.These changes might consist of an important molecular mechanism underlying methanol- and ethanol-promoted tobacco growth.

Abstract:Golden Ulmus pumila is a natural golden leaf mutant of U.pumila.The genetic analysis revealed that the inheritance of yellow-leaf phenotype belongs to cell nucleus and showed character separation in the next generation.Used the yellow seedlings and green seedlings as materials,the photosynthetic characteristics and leaf colouration machinsm were studied form the growth rate,pigment contents of leaves,photosynthetic rate,chlorophyll fluorescence and the ultrastructure of chloroplasts of leaves.The results showed:(1)The yellow seedlings developed slowly,and the net photosynthetic rate(12.5 μmol·m^-2·s^-1)was significantly lower than that of green seedlings(17.5 μmol·m^-2·s^-1),but the transpiration rate,stomatal conductance and leaf temperature were significantly higher than those of green seedlings.(2)The types of pigments were almost same,but the contents of 4 pigments of yellow seedlings were lower than those of green seedlings all the time and relatively stable.In the growth period,all kinds of pigment contents changed slightly in different months and the carotenoid content was always lower than the chlorophyll content.(3)The reduction of electron transfer efficiency through PSⅡof yellow seedlings was lower than that of green ones,(4)The inner membrane system of the chloroplasts developed incompletely and the grana stacked together imperfectly,which led to the reduction of the chlorophyll－protein complexes.Therefore,development defect in the endomembrane system of the chloroplast and the failure stack of the grana lamellae of yellow seedling led to the photosynthetic system developed incompletely,all kinds of pigment contents decreased in abundance,and then the color of leaves showed yellow,the photosynthetic capacity decreased and the seedlings grew slowly.

Abstract:Phenolic acids are one kind of important allelochemicals,which generally exist in crops and vegetables,as well as their cultivated soils.These metabolites are involved in plant allelopathic effect and continuous cropping obstacles.In this paper,we investigated the allelopathic effect of chlorogenic acid and its phytotoxic mechanism on lettuce seedlings by plant cell and physiology methods,in order to reveal the allelopathy and continuous cropping obstacles mediated by chlorogenic acid.The results showed that:(1)Root length,shoot length and fresh weight of lettuce seedlings were promoted by chlorogenic acid at low concentrations(0.1 and 1 μmol/L) and were inhibited at high concentrations(10,100 and 1 000 μmol/L).Chlorogenic acid displayed significant inhibitory effects on root length and fresh weight of lettuce at concentrations of 10 μmol/L and more.However,shoot growth of lettuce was not significantly inhibited by chlorogenic acid at each concentrations used.(2)After treated by chlorogenic acid,the mitotic index of lettuce root tips was significantly decreased,and with the concentration of chlorogenic acid increasing,the proportion of cells in each mitotic phase was also significantly reduced,resulted in arrest of cell division.(3)Under low concentrations(0.1,1.0 and 10 μmol/L),chlorogenic acid had no significant effect on cell viability in lettuce root tips.However,high concentrations of chlorogenic acid(100 and 1 000 μmol/L) significantly increased the number of dead cells,and caused losing of cell vitality in lettuce root tips.(4)Fluorescence staining of DHE showed that low concentrations(0.1 and 1.0 μmol/L) of chlorogenic acid had no significant effects on the accumulation of reactive oxygen species(ROS) compared with the control.However,when the concentration of chlorogenic acid reached 10 μmol/L,a lot of ROS accumulated in lettuce roots with concentration increasing.These results indicated that under the stress of chlorogenic acid,ROS in lettuce was induced and then accumulated.Furthermore,the cell division and viability were inhibited,resulting in growth and development arrest in lettuce seedlings.

Abstract:To study the salt-tolerance mechanism of Thermopsis lanceolata,we determined the growth parameters,organic osmotic adjustment substance contents and inorganic ions such as Na⁺,K⁺ and Ca²⁺ cation contents of T.lanceolata test-tube plantlets which have been growing for 30 d under 0,0.2%,0.4%,0.6%,0.8%,1.0% NaCl and Na₂SO₄ Stress.The results showed:(1)With NaCl and Na₂SO₄ concentration increasing,the contents of free proline and soluble sugar in leaves of T.lanceolata test-tube plantlets increased significantly,but the increasing extent of free proline under NaCl stress was greater than that under the same Na₂SO₄ concentration stress,while the increasing extent of soluble sugar content under NaCl stress was smaller than that under the same Na₂SO₄ concentration stress;the soluble protein content increased first then decreased with the increasing of NaCl concentration while went up continuously with the increasing of Na₂SO₄ concentration.(2)Na⁺ content of T.lanceolata test-tube plantlets went up continuously with the increased of the NaCl and Na₂SO₄ concentrations and the Na⁺ contents of all treatments were significantly higher than those in the control.Ca²⁺ and K⁺ content in leaves presented a decreasing trend,which were significantly lower than that of the control,respectively.In roots,K⁺ content first increased and then declined.Compared with NaCl,Na₂SO₄ stress caused a lower increase of Na⁺ content and lower reduction of K⁺ and Ca²⁺ contents in leaves;Na⁺/K⁺and Na⁺/Ca²⁺ ratios increased with the increase of salt content;In leaves,Na⁺/K⁺and Na⁺/Ca²⁺ ratios under NaCl stress were higher than that under Na₂SO₄ stress,while Na⁺/K⁺and Na⁺/Ca²⁺ ratios in roots were lower than that under Na₂SO₄ stress.T.lanceolata test-tube plantlets under salt stress may adapt to salt environment depressing Na⁺ contents,increasing soluble sugar and soluble protein contents in leaves,higher K⁺ and Ca²⁺ contents and decreased Na⁺/K⁺and Na⁺/Ca²⁺ ratios in roots.In words,the adaptation of T.lanceolata to NaCl stress was smaller than that to Na₂SO₄ stress.

Abstract:In order to uncover the mechanism of phosphorus(P) efficiency in utilization in Eucalyptus,we investgated the sparingly-soluble phosphates uptake and physiological response of root system and architecture to P deficiency condition at seedling stage using ‘Guanglin 9’ by hydroponics and pot-culture experiments.It was suggested that:(1)P uptake by Eucalyptus seedlings root was up to 4.24 mg/plant under low P condition of AlPO₄,which was similar to those under low P condition of water-soluble P and Ca₃(PO₄)₂.(2)Formation of shallow root was induced by P deficiency and applying P fertilizer at the topsoil (0～20 cm),which resulted in the obvious increasing ratio of root surface and root tip number between topsoil and subsoil (20～40 cm) compared with normal P treatment.(3)15 days after low P stress,H⁺-ATPase activity improved significantly in Eucalyptus seedlings and the bromocresol purple indicator turned yellow at root tip.Secreting activity of acid phosphatase from root significantly improved under P deficiency related to normal P treatment,and further improved with the extension of low P stress (10,15,20 days).Moreover,Al toxicity and P deficiency stress can significantly induced the secretion of oxalic acid from root,and the secreting amount of oxalic acid under both Al and P deficiency conditions was significantly larger than that under the control and P deficiency conditions.These results indicated that strong uptake ability of sparingly-soluble phosphates,shallow root system induced by P deficiency and both Al toxicity and P deficiency conditions,acidification of root tip and secreting acid phosphatase and oxalic acid from root possibly contributed to the mechanism of resistance to Al toxicity and P deficiency in acid soil in Eucalyptus seedling.

Abstract:Drought is the most important factor on restricting plant growing,and drought resistance of plant will influence vegetation construction largely.Though controlling water by potted planting drought stress experiment(80%,60%,45%,30% and 20% of maximum field capacity,belonging to control,middle water stress,moderate water stress,severe water stress,and very severe water stress,respectively),meanwhile design natural drought experiment after sufficient irrigation as control.The anatomical,physiological and biochemical characters were analyzed,to understand its affect to physiological and biochemical indexes:leaf anatomical characteristics,leaf relative water content(RWC),chlorophyll content(Chl),net photosynthetic rate(P_n),soluble sugar content(SS),cytomembrane permeability and MDA content of 3 Atriplex L..The results showed that:(1)Three testing plants owned typical leaf structural characters to fitting drought environment.Leaf organization structure form under drought stress condition showed that palisade tissue was thinning gradually,spongy tissue was thinning then thickening and mesophyll structure tightness (CTR) also appear was first lowered and then stimulated.(2)Along with the increasing of drought stress,SS was also increased while RWC was decreased;three Atriplex L.can maintain above 52% of RWC under lower water content in soil.(3)Under drought stress,T_r,P_n and amount of Chl all had a notable change.(4)Under drought stress,cell membranes of three Atriplex L.were harmed obviously.Drought resistance of three Atriplex L.under drought stress comprehensively showed that Atriplex canescens ssp.aptera＞Atriplex canescens ssp.canescens var.laciniata Parish＞Atriplex canescens(Pursh) Nutt.

Abstract:In order to clarify the mechanism of silicon enhancing plant salt resistance,Cucumis sativus L.cv ‘Jinyou No.1’ was grown in the hydroponic solution with silicon and NaCl.The effects of silicon on growth,photosyntheisis,osmotic adjustment and ion accumulation in cucumber seedlings were investigated.(1)Application of silicon alone had no effects on cucumber growth,while it partly reversed the salt-induced reduction in plant growth,chlorophyll content,water content,photosynthesis,stomatal conductance and transpiration.(2)The osmotic potential of silicon application was lower at beginning of salt stress,then became higher than salt alone application.Meanwhile,the osmolytes,especially,the sucrose levels,but not the proline,were significantly increased than that without silicon application under salt stress.The soluble protein content was not affected by silicon application.(3)Na⁺ concentration was increased while K⁺ concentration and K⁺/Na⁺ ratio were decreased in salt-treated plants.While,this tendency was partly reversed by silicon application,especially in the leaves.It can be concluded that silicon application decreases Na⁺ toxicity and improves the water status in plant,which allows a higher photosynthesis and growth rate,lead to salt tolerance.Osmotic adjustment,which has little effect at the beginning of salt stress,is not the main factor of silicon improving the salt tolerance.

Abstract:In this study,the antioxidant activities of the polyphenolic compounds in the bulbs of three Lilium species(L.concolor,L.pumilum and L.davidii var.unicolor) were investigated with a view to their exploitation as a potential source of natural antioxidants.The polyphenolic contents,antioxidant activities(ABTS+scavenging activity,superoxide radical scavenging activity,hydroxyl radical scavenging activity,cupric-reducing reducing capacity and lipoperoxidation activity) and 11 monomeric phenolic contents were analyzed.The results showed that total polyphenolics content and antioxidant activities of two wild Lilium species were significantly higher than those of L.davidii var.unicolor.Although the composition of monomeric phenolics from the bulbs of three Lilium species were not identical,the gallic acid,cyanidin 3-rutinoside chloride,(+)-catechin,(-)-epicatechin,myricetin,rutin,p-coumaric acid and kaempferol were present in all these species.Furthermore,the polyphenolic compounds of bulbs from three Lilium species exhibited a significant positive correlation with ABTS radical cation scavenging activity,superoxide radical scavenging activity,cupric-reducing antioxidant capacity and lipoperoxidation activity,excepted with hydroxyl radical scavenging activity.These results strongly suggest that wild lily bulbs have more important potential in the development food or medicine resources for their better antioxidant properties.

Abstract:A method for the determination of low molecular weight organic acids in roots,stems and leaves,and root exudates by ion chromatography (IC) was established,and the varied characteristics of low molecular weight organic acids in roots,stems and leaves,and root exudates of four species seedlings were detected,which provided evidence for revealing the role of organic acids in plant.The recoveries and detection limit of low molecular weight organic acids were in the range of 91.10%～105.42% and 0.12～0.36 mg/L,respectively.The determination coefficient of linear equation (R²) ranged from 0.965 3～0.998 8.Oxalic,citric,malic,succinic and tartaric acids were determined by IC in roots,stems and leaves,and root exudates of four plant species.Oxalic,citric and malic acids were the dominant organic acids.The composition and concentration of organic acids were influenced by plant species and organ,the interspecific differences were in the organic acids concentrations between root exudates and roots,stems and leaves.The results provided a reliable method for study organic acids of plant organ and root exudations,and provided evidence for understanding the role of organic acids in plants under environmental stress.

Abstract:With broccoli as test material,a field experiment was carried out to investigate the effects of 0.15 mmol/L salicylic acid(SA) on physiological characteristics,yield and quality of broccoli under different lower limits of flood irrigation.The results showed that:(1)The leaf relative water content and water potential and chlorophyll content decreased,while the blade penetration proline(Pro) and malondialdehyde(MDA) and soluble protein(Pr) content were gradually increased with the lower of irrigation limit;the flower ball weight and vitamin C content(Vc) decreased with the lower of irrigation limit;on the contrary,the nitrate and soluble solids contents were increased.(2)When spraying 0.15 mmol/L SA significantly increased the leaf relative water content and water potential,osmotic adjustment substance content,yield and quality,while reduce the membrane lipid peroxidation product and MDA content,of which 45% irrigation limit is the most obvious,60% followed,75% minimum.Thus,the suitable concentration of exogenous SA enhance its resistance to drought stress by improving water in broccoli leaves and leaf osmotic adjustment content and reducing membrane permeability,and the lower limit of 60% with spraying 0.15 mmol/L SA handled better.

Abstract:In order to investigate the effects of Cinnamomum japonicum leaf litter addition on the growth and photosynthetic characteristics of Impatiens balsamina,we conducted a pot experiment.Four litter addition treatments 0(CK),20(L),40(M),80(H) g·pot^-1 were applied.The results showed that the biomass and basal diameter of I.balsamina decreased significantly in M and H treatments,but no obvious change was observed in plant height among all the treatments.Chlorophyll contents of both M and H treatments were significantly inhibited.In treatments M and H,both net photosynthetic rate(P_n) and water use efficiency(WUE) were significantly lower than that of CK,while the three gas exchange parameters,stomatal conductance(G_s),intercellular CO₂ concentration(C_i) and transpiration rate(T_r) were notably higher than those of CK.P_n-PAR curve and P_n-C_i curve showed that under the saturation of light and CO₂ conditions both maximum net photosynthetic rates(P_{n max}) declined with the increasing amount of litter leaf addition,apparent quantum efficiency(AQY),dark respiration rate(R_d),RuBP carboxylation efficiency(CE) and light respiration rate(R_p) decreased as well.After adding C.japonicum leaf litter 36 and 67 days,no obvious effects were witnessed on the growth of I.balsamina,whereas inhibitory effect was observed obviously after 58 days.Overall,C.japonicum leaf litter addition reduced the content of photosynthetic pigments of I.balsamina,inhibited photosynthetic capacity,weakened adaptability to the environment,restraining the growth of the plant ultimately.

Abstract:A pot experiment was performed to study the effectiveness of tartaric acid and EGTA and their combined use in enhancing remediation of Cd contaminated soil with Ricinus communis L.,so as to discuss the feasibility of chelating agents and antidote in phytoremediation of heavy metal contaminated soil.The results showed that:(1)All treatments except single use of tartaric acid could significantly increase acetate-extractable Cd concentrations in soils.The acetate-extractable Cd concentrations in EGTA & tartaric acid treatment were 1.41～2.49 times higher than that of the control.(2)The Cd concentration in Ricinus communis L.shoots increased significantly with EGTA treatments,but high dose of EGTA demonstrated toxic effects on plant roots.The EGTA & tartaric acid treatments were more effective for Cd detoxication,translocation and biomass accumulation,which Cd accumulations in shoots are 4.56～8.32 times higher than that of control.As such,the phytoremediation efficiency is increased.(3)Statistical analysis reveals significant positive relations between the acetate-extractable Cd concentrations and the Cd content in leaves,the Cd accumulation in shoots,and cadmium removal rates in soil,respectively.Therefore,EGTA combined with tartaric acid can effectively improve Cd accumulation capacity in Ricinus communis L.shoots by adjusting Cd bioavailability and reducing its physiological toxicity.

Abstract:In natural and man-made protected plantations,cycling of nutrient is an important aspect as significant amounts of nutrients are returned to the soil through litter fall and become available for reabsorption.Nutrient distribution,accumulation and cycling of Quercus aquifolioides shrublands in the eastern slope of the Zheduo mountain were studied.The results showed that:(1)Nutrient concentration differed somewhat according to components.The nutrient elements patterns were N>K>Ca>Mg>P in leaf and branch components and Ca>K>N>Mg>P in stem and belowground components.(2)The total nutrient standing stocks were estimated to be (kg/hm²):N(252.67),P(49.22),K(197.01),Ca(650.06),and Mg (51.18).The proportions of these nutrients distributed in the shrub component,herb component and litter component were 88.61%～96.10%,0.64%～4.22% and 2.54%～9.25%,respectively.(3)Most of the nutrients in Q.aquifolioides shrub were distributed in the belowground components (67%～81%).The abundant nutrient reserve in roots favored for resprouting of Q.aquifolioides after fire and coppicing.(4)The nutrient annual accumulations in the shrubs were [kg/(hm²·a)]:Ca(20.82)>N(7.46)>K(6.12)>P(2.33)>Mg(1.55).The nutrient utilization coefficient of the five elements was estimated to be 0.09,and the nutrient cycling coefficient to be 0.60,and the nutrient recycling period was also estimated.The nutrient use efficiency of Q.aquifolioides shrublands was low and the recycling period of nutrient was long.

Abstract:Grassland ecosystem is one of the most important terrestrial ecosystems and plays a critical role in global carbon cycle.However,compared with other ecosystems,studies of carbon tock in grassland ecosystem,especially in the Loess Plateau were relatively less.Shrubs are the dominant plant life form in Loess Plateau,Northern China.Based on the continuous measurement of soil respiration and net ecosystems CO₂ exchange rate within and outside of the Artemisia gmelinii shrub patch in the grassland of Loess Plateau by using closed chamber method in the growing season of 2012,the temporal variations of soil respiration and net ecosystems CO₂ exchange were studied with the effects of temperature and soil water content.The results are as follows:(1)The diurnal variation of soil respiration rate both within and outside of the shrub patch showed an asymmetric single-peak pattern,while that of net ecosystems CO₂ exchange rate both showed sigmoid curve under normal circumstances and “twin peaks” type with the water deficit.The peak values of soil respiration rate appear in August while net ecosystems CO₂ exchange rate in September.(2)The daily averages of soil respiration and net ecosystems CO₂ exchange rate within the shrub patch are significantly higher than that outside.The averages of soil respiration rate within and outside of shrub patch in the growing season are 5.49 and 2.93 g·m^-2·d^-1,respectively,and are close to the observed value in May.(3)The averages of net ecosystems CO₂ exchange rate within and outside of shrub patch in the growing season are -3.86 and -1.19 g·m^-2·d^-1,close to that observed in May and July,respectively.“fertile island” is observed under the shrub,which can contribute to the carbon accumulation in this region.Soil moisture and soil temperature are the key factors controlling the variation of soil respiration rate,both within and outside of shrub patch,while net ecosystems CO₂ exchange rate was mainly controlled by soil moisture.

Abstract:Stipa purpurea steppe is the largest area and most important community type of alpine steppe ecosystems in Qinghai-Xizang Plateau.Currently,the number of studies on the S.purpurea steppe classification and ordination is still lacking.In this study,the typical S.purpurea steppe in Qinghai Plateau was selected as subject.Multivariate statistics methods including TWINSPAN(Two-way Indicator Species Analysis) and CCA(Canonical Correspondence Analysis) were used to classify the S.purpurea steppe on the basis of investigating a large number of vegetation communities in this region.The results showed that:(1)The species composition of S.purpurea steppe in the study area is relatively simple.The dominant families of seed plants were Gramineae and Compositae,and the dominant areal types of genera were North temperate type.(2)The 90 transects of S.purpurea steppe in Qinghai Plateau could be merged into 8 main ecological associations:Ass.Stipa purpurea+Poa indattenuata,Ass.Stipa purpurea+Kobresia humilis,Ass.Stipa purpurea+Astragalus polycladus,Ass.Stipa purpurea+Kobresia pygmaea,Ass.Stipa purpurea+Potentilla bifurca,Ass.Stipa purpurea+Saussurea arenaria,Ass.Stipa purpurea+Leontopodium humilum and Ass.Stipa purpurea+Kengyilia thoroldia.(3)The major environmental factors influenced the distribution of S.purpurea steppe ecological associations in Qinghai Plateau firstly were space factors(altitude,longitude and latitude) and heat factor(temperature),then water factors(precipitation,wetness).(4)For internal ecological association division of S.purpurea steppe community,CCA could complement and correct the TWINSPAN results,make the classification more realistic ecological significance,and reflect more clearly relationship between the associations and environmental gradients.

Abstract:The new geographical distributions of three species in Adiantum L,A.meishanianum,A.sinicum,and A.menglianense are recorded in this paper.A.meishanianum is found in Xishuanbanna and Puer,Yunnan,A.sinicum in Shiping,Yunnan,and Yanyuan,Pingshan,Dukou and Leshan,Sichuan,and A.menglianense in Baise,Guangxi,and Xishuanbanna,Chuxiong and Yuxi,Yunnan.The diagnostic characters are given between these three species and their respective relatives.Neighbor-joining tree of Ser.Caudata(including eight species,without A.soboliferum) based no rbcL gene is provided.A complete key of Ser.Caudata(including nine species) is also provided.

Abstract:The species Isodon racemosus (Hemsley) H.W.Li,Chrysosplenium lanuginosum J.D.Hooker & Thomson.,Tylophora henryi Warburg and Monotropastrum humile (D.Don) H.Hara are reported as new records in Shaanxi,which has an important significance for supplementing the plant resource of Shannxi and studying the flora of Qinling Mountain.

Abstract:Ribes graveolens Bge.is reported as new record in Northeast China and Rheum palmatum L.is reported as new record in Heilongjiang Province.

Abstract:Archegonium,the female reproductive organ in bryophytes,pteridophytes and gymnosperms,consists of an egg cell,a ventral canal cell and one to several neck cells(neck canal cells).Among them,neck cells are the only effective structure for male gametes to enter the archegonia and accomplish fertilization,and therefore,play essential roles during the archegonial development and fertilization.Here,we review the research progress on the formation process,development and structural characteristic of neck cells,in particular about the function during fertilization.In addition,we point out the remaining problems in current research and give an outlook to the future research on neck cells.