Abstract:The micromorphology of leaf epidermal surfaces of 29 species of Vicia L. from China were observed by using light microscope and scanning electron microscope. Both the adaxial and abaxial epidermal cells are polygonal or irregular in shape, with anticlinal walls undulate or straight and arched. Most species are amphistomatic, with some others hypostomatic or hyperstomatic. All stomata are anomocytic. Tow kinds of trichomes could be distinguished, non-glandular and glandular, and most species have both kinds. The cuticular wax ornamentation are smooth, striation or granular striation, or with platelet-like and flake-like wax. Some systematic significance of these epidermal features were discussed.

Abstract:Based on the highly homologous EST sequence of phosphoethanolamine N-methyltransferase(PEAMT) gene obtained from drought-induced cDNA library of Cleistogenes songorica,a full-length cDNA of PEAMT gene was isolated from C.songorica.Full length of CsPEAMT was 2 104 bp,containing a 1 506 bp ORF and encoding 501 amino acids.Comparative analyses revealed that the amino acid sequence encoded by CsPEAMT gene was highly homologous to PEAMTs from other plant species,and CsPEAMT had the highest similarity with that of Sorghum bicolor and Zea mays(93%).The expression patterns of CsPEAMT during drought stress were investigated by real-time quantitative RT-PCR analysis.The results showed that drought stress induced a large number of the gene expression in root and leaf.And the CsPEAMT expression level in leaf and root are 43.35 times and 13.25 times higher than that of control,respectively,then the expression level began to decrease afer rewatering.This study indicated that CsPEAMT may be a drought-related gene.

Abstract:The whole open reading frame(ORF) sequence of HbNAC24 was cloned from cDNA of Hevea brasiliensis latex,and the transcriptional activation activity and expression profile of HbNAC24 were carried out using Real-time PCR and yeast assay system.The results indicated that:(1)HbNAC24 has an OPR of 1 167 bp,encoding a protein with 388 amino acids.It’s N-terminal region had a conserved NAC domain from amino acid 7 to 174.(2)Yeast assay showed that HbNAC24 protein possessed transcriptional activation activity and the activation domain was located in the highly divergent C-terminal region in yeast assay system.(3)Sequence alignment and phylogenetic analysis revealed that HbNAC24 was a member of a NAC transcription factor family belonging to TIP subgroup.(1)The real-time PCR indicated that expression level of HbNAC24 in leaves was significantly higher than that in other parts of the rubber tree.The expression of HbNAC24 in latex was induced by tapping and jasmonic acid(JA).The results suggested that HbNAC24 may be involved in response to stress and developmental processes in rubber tree.

Abstract:LIM domain proteins are important members of transcription factors in eukaryotes,which play important roles in the regulation of growth and development including gene transcription,organizing cytoskeleton and signal transduction.The full-length cDNA of GhLIMa was obtained by electronic cloning and RT-PCR method(The accession No.of Genbank is DQ672342) from salt resistant cotton materials ‘H15’.It includes 627 bp open reading frame and encodes a protein about 23.2 kD which is composed of 208 amino acids.Bioinformatics analysis revealed that GhLIMa contains two full LIM domain structures.The amino acid sequences of LIM from cotton and other species were selected and analyzed by multi-sequence alignment.The results showed that they have high similarity (>78%) with those of Ricinus communis,Theobroma cacao,Populus trichocarpa.The expression of GhLIMa from leaves and roots of salt tolerance and salt sensitive cotton material was detected by quantitative real-time RT-PCR.The results showed that GhLIMa gene can be induced by salt in leaves and roots.It suggested that GhLIMa plays an important role in cotton response to salt stress.

Abstract:To investigate the differences in expression of xyloglucan endotransglycosylase gene(PbXET) in ‘Dangshansuli’ and its russet mutant ‘Xiusu’ pear(Pyrus bretschneideri Rehd.),we cloned the cDNA fragment of PbXET by rapid amplification of cDNA ends(RACE).The level of relative expression of PbXET in leaf,exocarp and sarcocarp and in the exocarp at different stages(days after full bloom,DAFB) were determined by real time quantitative reverse transcription-PCR(qRT-PCR).The results showed that:(1)PbXET3,with the accession number of KJ690921 in the National Center for Biotechnology Information(NCBI),and PbXET4,with the accession number of KJ690922 in NCBI had a open read frame(ORF) of 903 bp and 891 bp,respectively,encoding the corresponding polypeptide of 300 amino acids or 296 amino acids.Clustering analysis by sequences of amino acids showed that the structure of PbXET3 and PbXET4 in pear plant had a closer relationship to MdXET-3 and MdXET-5 in apple plant respectively.(2)The results of semi-quantitative PCR demonstrated that PbXET3 and PbXET4 had expressed in leaf,exocarp and sarcocarp of ‘Dangshansuli’ and its russet mutant ‘Xiusu’ pear at 150 DAFB,but expression of the two genes were lower in leaves and higher in exocarps and sarcocarps.Compared with PbXET4,the relative levels of PbXET3 expression were lower in leaves,but were higher in exocarps and sarcocarps.(3)The expression of PbXET3 and PbXET4 genes showed different trend lines of the dynamic change in exocarps of ‘Dangshansuli’ and its russet fruit mutant ‘Xiusu’ pear.The expression of PbXET3 decreased sharply after the beginning of exocarp turning russet(100 DAFB),whereas,the expression of PbXET4 decreased before 100 DAFB in exocarps of ‘Xiusu’ pear in compare with that of ‘Dangshansuli’ pear.It was postulated that the expression of PbXET3 and PbXET4 may be involved in formation of russet exocarps in pear fruit,and the difference in the expression of the two genes could be one of the important reason why the structure of exocarps cells in ‘Xiusu’ pear altered.

Abstract:NAC transcription factor plays an important role in the response of abiotic stresses.In the present study,we isolated a NAC gene designated TaNAC5 from wheat.TaNAC5 ORF is 924 bp,which encodes 307 amino acids.Comparison of amino acid sequences and phylogenetic analysis indicated that TaNAC5 contains the conserved domains of NAC family and has close relationship with ZmNAC5.Real-time quantitative polymerase chain reaction (QPCR) assay revealed that TaNAC5 expression was induced after osmotic stress,low temperature,ethylene and H₂O₂ treatments,but inhibited after salt stress and ABA treatments.These results suggested that TaNAC5 participates in the response of abiotic stresses and related signaling molecules.

Abstract:A ethylene-responsive factor gene,named NhccERF1,was isolated from bud of non-heading Chinese cabbage(Brassica campestris ssp.chinensis),named as “Subai 2”,which has stamens mutation and its maintainer lines by cDNA-AFLP technique.(1)Sequence analysis showed that the full length sequence of NhccERF1 gene was 807 bp,encoded 268 amino acids residues.(2)RT-PCR results showed that NhccERF1 gene have a highly expression in stamen,petal,carpel in mutant than in maintainer lines.(3)Quantitative RT-PCR analysis indicated that,external ethylene increased the gene expression,while external AgNO₃ inhibited its expression.This results suggested that the gene might involved in stamen mutant.

Abstract:In this research,a full-length cDNA sequence of 4CL related to flax lignin synthesis is cloned by RACE-PCR technique on the basis of the segment of this gene cloned freviously.The complete cDNA sequence of 4CL is 1 957 bp in length,with a complete open reading frame of 1 650 bp.The encoded protein contains 549 amino acids,with a molecular mass of 60 kD and a pI of 5.3.Random coil and α-helix are the main secondary structure of the protein.Phylogenetic analysis indicated that there is high similarity between flax 4CL gene and that of Thellungiella halophila.The full-length cDNA sequence has been registered in GenBank,with an accession number of KC832864.A 413 bp CDS fragment of 4CL is amplified by PCR to construct the RNA interference vector p1301M-4CL,which is transformed to flax by agrobacterium-mediated method.Seven transgenic seedlings selected randomly are detected by GUS and PCR.The results showed that the RNAi vector construction has been integrated into flax genome,which leads to evidently depression of the expression of 4CL gene in flax.

Abstract:In order to study the function of AtTIP5;1 gene,we employed Saintpaulia ionantha leaves as receptor materials and optimized the genetic transformation conditions.The transgenic plants were exposed to high concentration of boric acid and the resistant ability was evaluated.The results showed:(1)The receptor leaves pre-cultured for 2 d,infected for 15 min,co-cultured of 2 d with 100 μmol/L AS,and selected with 40 mg/L hygromycin were the optimum transformation conditions.(2)After PCR and RT-PCR screening,17 transformed plants containing AtTIP5;1 transgene were obtained.(3)Transformed and control plants were treated by high concentration boric acid (3 mmol/L) and physiological indexes of these plants were evaluated.The results indicated that the AtTIP5;1 expression could be induced by boron.Transgenic plants showed a lower degree of plant tissue browning,leaves curling,and a higher rate of dry matter,soluble sugar and soluble protein content.Meanwhile,the increase of POD and SOD activities were weaken.Our results demonstrate that AtTIP5;1 trasformation can improve the tolerance of S.ionantha to the high boron stress.Our study is helpful for further investigation on AtTIP5;1 gene function and gene engineering in breeding of S.ionantha.

Abstract:Molecular characterizations of Astragalus L.species can elucidate the relationships among the species and provide more information about the taxonomy of this valuable genus.In this study,the genetic relationships among 45 Astragalus accessions from Mongolian Plateau and its surrounding areas were analyzed using inter-simple sequence repeat (ISSR) primers.11 selected ISSR primers generated a total of 188 valid loci,of which 178 exhibited polymorphisms.Unweighted pair-group method of cluster analysis based on dice similarity values separated the accessions into seven groups.Seven species were recognized within these groups.A.koburensis was placed in the same group as A.galactites accessions,showing that this species was only variants or ecotype of A.galactites.Pedicel variants of A.scaberrimus and pod variants of A.variabilis were also been detected by forming distinct subgroups within the clusters of these species.A.leansanicus was separated from A.limprichtii.The grouping of accessions was generally consistent with principal coordinate analysis (PCoA) and the results showed that it was reasonable to organize the species of Astragalus at section level,but some sections and the affiliation of some species should be modified.Application of multiple DNA marker systems and more samples from different species will help to reveal more accurately the phylogenetic relationships among Astragalus species.

Abstract:In this study,a kind of psammophytes,Caragana korshinskii seeds,were used as experiment material.The seeds were treated by electric field and the seedling growth was under drought stress conditions abd the expression difference of genes in the C.korshinskii young leaves were tested by mRNA differential display technology(DDRT-PCR).In order to compare the gene expression difference,young leaf tissues were classified three samples include nature control(called CK),drought stress control(called SCK) and electric field treatment group(strength 2 kV/cm,frequency 15 kHz,time 5 min,called ET).The 3 anchor primers and 26 random primers were used to form 78 primer pairs.The DDRT-PCR was carried out 234 PCR reactions for the three kinds of samples.The cDNA bands showed significant difference between three young leaf tissue samples.(1)Compared with CK,SCK appeared 282 novel bands and disappeared 179 bands,and ET appeared 303 novel bands and disappeared 200 bands.Besides,compared with SCK,ET appeared 236 bands and disappeared 257 bands.(2)The novel bands were recovered and three differentially expressed cDNA fragments were obtained.All of the expressed sequence tags(EST) had the homology with known cDNA clones in Genbank databases.EST-1 was similar to Glycine max uncharacterized LOC100305895(LOC100305895) and the identity was 76%;EST-2 was similar to Cicer arietinum probable UDP-N-acetylglucosamine——peptide N-acetylglucosaminyltransferase SEC-like(LOC101506182),transcript variant X2 and the identity was 88%;EST-3 was similar to Lotus japonicus clone JCVI-FLLj-5M12 and the identity was 88%.(3)After Blastx comparision,EST-1 was similar to the 145-195 aa of 1-deoxy-D-xylulose 5-phosphate reductoisomerase(390 aa) and the identity was 52%;EST-2 was similar to the 706-744 aa of O-linked GlcNac transferase like protein(744 aa) and the identity was 97%;EST-3 was similar to acyl-CoA-binding protein(90 aa) and the identity was 97%.Our result provides experimental basis to analyze the biological mechanisms of drought resistance improvement induced by electric field treatment on plant seeds from the gene expression difference.

Abstract:Plant leaves play significant role for improving the quality of urban environment by acting as biological filters to capture atmospheric particulate matter.In this paper,the captured amount of TSP(total suspended particles) and PM_2.5(particles with diameter≤2.5 μm) per unit leaf area for 20 plants commonly used for urban greening in Beijing were measured by water washing methods,and the micro-structure of leaf surface of these plants were investigated by scanning electron microscopy.The mechanism that micro-structure of leaves surface how to affect the ability of capturing atmospheric particulate was discussed,through analyzing removal TSP and PM_2.5 numbers of 20 kinds of road plant with different surface micro-structure.The results showed:(1)There is significant difference in the captured amount of TSP and PM_2.5 per unit leaf area among the plant species,with the variation ranges of 0.40～3.44 g/m²(TSP) and 0.04～0.39 g/m²(PM_2.5),respectively.(2)The difference in groove width on leaf surface may be the main reason for explaining the difference of TSP and PM_2.5 retention among plant species;the grooves too broad and too narrow are not beneficial to trap particulate matter.The captured amount of PM_2.5 on leaf surface increases with increasing groove depth.(3)There are higher particle retention numbers for that plant with more stoma per unit leaf.The results have illustrated that captured amounts of TSP and PM_2.5 per unit leaf area on shrubs and lianas are greater than that on trees;leaf surface trench width of PM_2.5 holdup at around 5 μm larger;sycamore(Platanus acerifolia),hibiscus(Hibiscus syriacus) and Euonymus(Buxus sinica) unit leaf area stranded TSP and PM_2.5 amount compared with other test plants are larger.

Abstract:In order to have a knowledge of pollen morphology and structure as well as male reproductive characters of Cypripedium japonicum Thunb.,we used SEM(scanning electron microscopy) and TEM (transmission electron microscopy) and fluorescence microscopy to observe pollen ultrastructure and the process of pollen tube growth.The results showed that:(1)Pollen grain presented prolate,smooth surface with a small amount of glue materials and without any characteristics,while some of the surface had two or more deeper depression with spherical protrusions inside.(2)Pollen wall divided into the inner wall with cellulose pectin composition and the outer wall of rod-shaped pillar structure,with covering layer outside.Germ cells were nearly round,of large and dense nucleus;vegetative cells were more curved,with nuclei and cytoplasm dispersion.Pollen cells contained a large number of mitochondria,plastids,vesicles and other organelles,and were rich in starch,protein and polysaccharide.(3)Pollen tubes grew along the direction of elongation of the ovary wall after germination.Twenty days after pollination (DAP),few pollen tubes grew on the ovary wall.A huge number of callose plugs presented in pollen tubes which changed the elongation direction to the middle of ovule 30 DAP.Along with pollen tubes approaching to the ovules,fertilization basically completed 50 DAP.Our study suggested that pollen could develop normally in C.japonicum,which did not hinder the process of generative propagation.

Abstract:The distribution characteristics of ATPase in phloem and the flesh sink-cells of fruit in different developmental stages of Ziziphus jujuba Mill.cv.Lingwuchangzao were studied by ATPase ultracytochemical location technology.The result showed that:(1)In the first rapid growth of fruit,there were abundant plasmodesmata in the SE-CC complex and its surrounding cells,making the phloem a symplastic integration.There were abundant plasmodesmata in the phloem parenchyma cells,but there were less ATPase sediments in various cells of phloem.(2)In the slower growth period,the distribution of ATPase sediments in various cells of phloem increased gradually.(3)In the second rapid growth of fruit,there were less plasmodesmata between the SE-CC complex and its surrounding parenchyma cells,resulting in the symplastic isolation between them.There were less plasmodesmata in phloem parenchyma cells and the flesh sink-cells,numerous vesicles and membrane bubbles were found in the sieve tube,phloem parenchyma cells and the flesh sink-cells.The ATPase activities were higher in plasma membrane,vacuole membrane,vesicle membrane,cell wall and intercellular space.To sum up,the photoassimilates unloading from sieve tube element was symplast pathway in the first rapid growth of fruit;the symplast pathway and apoplastic pathway existed simultaneously in the slower growth period;the photoassimilates unloading adopted mainly apoplastic pathway in the second rapid growth of fruit.The photoassimilates unloading pathway in phloem existed differences in different developmental stages of fruit.

Abstract:Based on a comprehensive survey of endogenous hormone in floral bud and characteristics of early defoliation during returning bloom,we indicated that:(1)The IAA and GA₃ in floral bud decreased after fruit harvest,while ABA showed up-down-up “S” curve.(2)Returning bloom of floral bud was controlled by the dynamic balance of the hormone.The rates of IAA/ABA,GA₃/ABA and (IAA+GA₃)/ABA showed up-down-up “S” curve after fruit harvest.The floral bud returned bloom,when IAA/ABA,GA₃/ABA and(IAA+GA₃)/ABA rate increased,while floral bud went into dormancy when the rate decreased.(3)The analysis of coefficients showed that the related coefficients for IAA/ABA rate and early defoliation rate,returning bloom rate in cv.Hosui were 0.805 and 0.774,respectively at the 5% significant level.The decreased of ABA in floral bud due to the early defoliation of ‘Hosui’ made the rate of endogenous hormone changes,which prevented the onset of dormancy of deciduous fruit trees with dormant nature and promoted the next growth cycle to commence,so the floral bud returned flower.

Abstract:Effects of different maturities(unripe,ripe and overripe)of tobacco on the changes in the content of water,PPO activity,polyphenols of ‘Yuyan 11’(a new kind of flue-cured tobacco) during baking process and the correlation between indexes were investigated.The results indicated that:(1)The tendency of the changes in the contents of water,PPO activity,total polyphenols in three maturity levels are similar:Water content of tobacco leaf gradually reduced;PPO activity slightly declined,then rapidly increased and finally sharply declined.The changes in the rutin content of unripe and overripe tobacco leaves were similar.The trend of rutin content in mature tobacco leaf was “decreased-increased-decreased-increased” slightly.The content of scopoletin in three maturities increased as a whole.(2)During the sensitive period in enzymatic browning reaction(48-66 h in the curing process),overripe tobacco had the lowest content of water and PPO activity,the contents of total polyphenols and chlorogenic acid were slightly lower than that in mature tobacco.The water and PPO activity contents of mature tobacco leaf were lower than that in immature tobacco leaf and higher than that in over mature tobacco leaf.The contents of total polyphenols and chlorogenic acid in mature tobacco leaf were the highest.The water and PPO activity contents of immature tobacco leaf were the highest;the contents of total polyphenols and chlorogenic acid in immature tobacco leaf were the lowest.The content differences of rutin and scopoletin among three maturities had no significant regularity.(3)During 48-66 h period,there was a significant negative correlation between the change of PPO activity and the accumulate speed of polyphenols:Unripe treatment reached an extremely significant level,mature treatment reached a significant level,and overripe treatment reached an insignificant level.It suggested that high PPO activity reduced the accumulation of polyphenols in immature and mature tobacco leaf significantly,and low PPO activity effected on the accumulation of polyphenols in overripe tobacco insignificantly.The result indicate that appropriately improving the maturity of harvested flue-cured tobacco,can promote the tobacco leaf water loss effectively,so as to reduce the PPO activity during the curing process,it is beneficial to prevent browning in tobacco leaves,thus improve the appearance and intrinsic quality of cured tobacco leaf.

Abstract:A pot experiment was conducted to study the effects of the decomposing walnut(Juglans regia L.) green husk on the growth of Brassica rapa L.var.chinensis seedling group.The results showed as follows:(1)The aboveground fresh weight of B.rapa L.var.chinensis seedling was inhibited significantly by each treatment at 20 d,45 d and 75 d after sowing;(2)The chlorophyll content of B.rapa L.var.chinensis seedling was significantly lower than that in CK at 20 d.As the time extended,the chlorophyll content of B.rapa L.var.chinensis showed a trend of decrease;(3)The activities of superoxide dismutase(SOD) and peroxidase(POD) increased during the observation period,but catalase(CAT) activity did not showed the significant change in 70 d;(4)The contents of soluble protein(SP) and proline(Pro) reduced with the increasing addition of walnut green husk,while the soluble sugar(SS) content was significantly lower than that of CK at 45 d and 75 d.Generally,the allelopathic intensity of walnut green husk on B.rapa L.var.chinensis seedling was strong at early time,but got weaker with prolonged time,and comparatively,high doses of green husk generated allelopathic effects earlier and stronger.

Abstract:In order to investigate the effect of decomposing walnut(Juglans regia L.) leaf litter on the growth of crops in walnut and winterness crops intercropping system,we applied a pot experiment.Radish(Raphanus sativus L.) seeds were sowed in the soil mixed with different amount of walnut leaf litter,and the indexes with respect to morphology,physiology and reproduction were determined as the radish growing.The results showed as following:(1)The seedling growth of radish was significantly inhibited by decomposing leaf litter at the primary stage of leaf litter decomposition and recovered its growth afterwards.(2)The stress response of radish induced by walnut leaf litter was obvious,especially at the primary stage of leaf litter decomposition and with high amount of litter addition(120,180 g/pot).It was indicated by decrease of photosynthetic pigments,increase of reactive oxygen and the induced osmotic stress.(3)During the period of measurement,MDA content of radish leaf was not increased obviously,which indicated that the radish can recover from stress by auto-regulation.(4)The plants treated by large amount of leaf litter(120,180 g/pot) produced darker seeds than that of the control and the plants treated by small amount of leaf litter(60 g/pot).The plants treated by 180 g/pot leaf litter produced seeds with lower germination rate than that of other treatments.These indicated the effect of seed quality.On the whole,decomposing walnut leaf litter can induce allelopathic stress on radish especially at the primary stage of its decomposition,but it won’t affect the yield of radish.It is recommended to retain walnut leaf litter and grow crops after a period of decomposition when practice the interplanting of walnut and radish.

Abstract:Taking Chorispora bungeana plantlets in vitro as material,we carried out the current study to investigate the effect of drought stress on a Qinhai-Tibet Plateau plant C.bungeana with solid-liquid culture medium.There were four drought levels being Set:the control (without adding PEG-6000,CK),mild drought stress (5% PEG-6000),moderate drought stress (20% PEG-6000),and severe drought stress (40% PEG-6000).The physiological characteristics of C.bungeana seedings in vitro,laying a foundation for adaptation mechanism of C.bungeana in drought environment were investigated.The results showed that:(1)With drought stress became more and more serious,the activity of antioxidant enzyme SOD and soluble sugar content were significantly increased.The SOD peak appeared earlier than that of POD,CAT,and APX.The activities of POD,APX,CAT and MDA content increased at first,and then decreased,which illustrated that all the four enzymes show different responses to drought stress and reactive oxygen species.(2)Hydrogen peroxide(H₂O₂) content and superoxide dismutase(O^-·₂) composition rate in the leaves quantitatively increased with the increase of drought stress over the time course;C.bungeana leaf relative conductivity initially increased,then decreased and increased at last.(3)Correlation analysis showed that,MDA content and the relative electric conductivity,soluble sugar content,SOD,APX activities,O^-·₂ and H₂O₂ contents presented a significantly positive correlation;soluble sugar content and SOD,POD activities,O^-·₂ and H₂O₂ contents presented a significantly positive correlation;the relative electric conductivity and protective enzymes,O^-·₂ and H₂O₂ contents presented significantly positive correlation.The results demonstrated that C.bungeana has a strong drought tolerance,and the membrane lipid peroxidation,osmotic regulator ,antioxidant enzyme system and oxygen reactive participated in the formation of comprehensive drought stress resistance of C.bungeana.And the above physiological indexes have correlations.It partly revealed the physiological mechanism of C.bungeana responding to drought environment.

Abstract:Taking 2 years old Melaleuca bracteata cv.‘Revolution Gold’ as the test materials,using potted approach simulate soil drought conditions,we set 6 levels of water supply treatment.They are 100% saturation soil moisture,80%(normal watering),60%(light drought),40%(moderate drought),20%(severe drought) and 10%(extreme drought),respectively,we studied its growth and physiological characteristics under different water treatments.The results showed that:(1)The plant height,crown width and leaf area were grew well under 100% saturation soil moisture condition,but had no significant difference compared with the control.Only their crown width slightly declined in 60% saturation soil moisture,but the growth were greatly reduced with the intensifying stress;(2)Under drought stress,the dry weight,dry weight/fresh weight and specific leaf weight had no significant difference compared with the control but the leaf modal traits greatly decreased;(3)With water stress intensifying,Ss,Pro and MDA contents in the leaves all showed a tendency to increasing;they were firstly increased and then decreased with time.With the extension of stress time,the activities of SOD and CAT in the leaves increased first and then decreased,but had no significant difference compared with the control at the end of the experiment.Drought stress significantly increased the content of chlorophyll(Chl a+b).The result indicated that the growth of M.bracteata cv.‘Revolution Gold’ were inhibited in different degree of drought stress,but they could ensure the normal photosynthesis by increasing the content of chlorophyll,mitigating drought damage.However,there was no mortality even under extreme drought stress ［the actual moisture content(4.42±0.82)%］,which indicated that the shrubs tolerate drought by reducing leaf area while increasing the contents of Ss,Pro and the activities of SOD and CAT enzymes.

Abstract:A pot experiment was carried out to study the growth,N nutrition,and physiological characteristics of Calligonum caput-medusae seedlings under different irrigation treatments (30%,40%,50%,60%,and 85% field water capacity (FWC)),and further to find out the suitable water condition to improve the plant growth.The results showed that:(1)Dry weight of the assimilating branches significantly increased with increasing amounts of irrigation.However,C.caput-medusae seedlings were infected with powdery mildew at the high irrigation level (85% FWC).(2)During the early growth stage,the assimilating branches,as growth center,accounted for 39.5% of the average whole-plant dry matter accumulation.Irrigation significantly promoted dry matter allocation to assimilating branches.During the late growth stage,the plants allocated less dry matter into assimilating branches,accounting for an average of 12.3% of whole-plant dry matter accumulation.In addition,the allocation proportion was not correlated with irrigation amounts.(3)The assimilating branches had high N and nitrate-N concentrations throughout the whole growth season.The N concentration of assimilating branches decreased,but the nitrate-N concentration had a fluctuation change with increasing amounts of irrigation.(4)The effects of irrigation on physiological characteristics of C.caput-medusae seedlings mainly occurred in the early growth stage.The nitrate reductase activity and chlorophyll content of assimilating branches were significantly limited under the low and high irrigation treatments (30% and 85% FWC).The plants had great MDA,soluble sugar and proline contents,but lower water potential under the lowest irrigation treatment.The MDA and proline contents decreased,but water potential and soluble sugar content increased with increasing amounts of irrigation.This suggested that C.caput-medusae seedlings had strong osmotic adjustment capacity to adapt to water stress.However,medium irrigation levels (50%～60% FWC) were recommended for establishing C.caput-medusae seedlings in this area due to plant growth,N assimilation and chlorophyll accumulation could be limited by over-irrigation and water stress.

Abstract:The experiment was carried out by sweet pepper cultivar ‘P13201’ in light growth incubator and nutrient solution to investigate the effects of pre-spraying different concentrations of 6-BA(5,10,20,50 μmol/L) on the growth and physiological and biochemical indexes of the sweet pepper seedlings under high temperature stress(40 ℃/30 ℃ day/night).The results showed that:(1)Growth index and chlorophyll content were significantly descended under high temperature stress,while plant height,stem diameter,shoot and root dry matter weight of sweet pepper treated with 10 μmol/L 6-BA concentration had no significant difference compared with the control check(CK),reduction of shoot and root fresh matter weight,contents of chlorophyll a,chlorophyll b and total chlorophyll of sweet pepper with this concentration were the smallest as well,among all the treatments.(2)Actual photochemical yield of PSⅡ(Yield),actual photochemical efficiency of PSⅡ(Ф_PSⅡ),optimal photochemical efficiency of PSⅡ in the dark(F_v/F_m) were significantly decreased under heat stress,while the non-photochemical fluorescence quenching(NPQ) showed a reverse trend.The extent of variation of four fluorescence parameters mentioned above in leaves of sweet pepper treated with 10 μmol/L 6-BA were the lowest among the all treatment groups,especially NPQ,displaying no significance with CK.(3)Affected by high temperature stress,the productivity of O^-·₂,activities of superoxide dismutase(SOD),ascorbic acid peroxidase(APX),peroxidase(POD) and malondialdehyde(MDA) content,relatively conductivity rate increased significantly.However,the productivity of O^-·₂.MDA content and relatively conductivity rate in leaves of sweet pepper treated with 10 μmol/L 6-BA were significantly smaller than those of T₀ treatment group(distilled water+high temperature).The activities of SOD,APX and POD revealed a remarkably increased tendency,namely,to rise by 50.5%,79.4% and 50.3% respectively.The study indicated that high temperature inhibited the growth of sweet pepper seedlings and made the above indexes in leaves changed a lot.There were dosage effect of 6-BA on the alleviation of high temperature in sweet pepper seedlings,10 μmol/L 6-BA,by means of enhancing activities of antioxidant enzymes,capturing and converting the light energy greatly,to maintain a normal growth,was the best relieving concentration to sweet pepper under heat stress.

Abstract:In order to get the method of alleviate salinity damage to Coptis chinensis Franch.under salt stress,we used exogenous 5-aminolevulinic acid(ALA) in the experiment.Several physiological indexes like the contents of photosynthetic pigment,chlorophyll fluorescence and photosynthesis parameters.of C.chinensis were measured treated by ALA under salt stress(NaCl with the concentration of 100 mmol·L^-1).The study results indicated that:(1)The exogenous ALA obviously increased the contents of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoids.(2)The levels of P_n,G_s,and T_r of C.chinensis seedlings were all decreased with the increased concentrations and treatment days under salinity stress,and the value of C_i increased with the opposite tendency.These results indicate that the main influencing factor to the decreasing net photosynthetic rate of C.chinensis is non-stomatal factors.(3)After treated with different concentrations of exogenous ALA,the P_n,G_s,and T_r were all increased with different degrees,and the level of C_i was decreased.(4)ALA applied in the experiment also increased maximum fluorescence(F_m,1.234),photochemical efficiency of photosystem II(F_v/F_m,0.849),photochemical efficiency(F_v′/F_m′,0.685),PSⅡ actual photochemical efficiency(Φ_PSⅡ,0.545),photochemical quench coefficient(q_P,0.872),decreased the levels of minimal fluorescence(F₀,0.211) and non-photochemical quenching coefficient(NPQ,0.251).As can be seen,ALA with the appropriate concentration of 50 mg·L^-1 could significantly alleviate the damage of salt stress to C.chinensis,reduce excess excitation dissipation and improve photochemical electron transport efficiency and efficiently protect from PSⅡ damage.ALA obviously promoted the salt resistance of C.chinensis under salt stress.

Abstract:A pot experiment was carried out to investigate the effects of decomposing leaf litter of camphor tree(Cinnamomum camphora) on growth and development of hot pepper(Capsicum annuum) and its progeny.The experiment consisted of four leaf litter treatments(25,50,75 and 100 g of camphor tree leaf litter were separately added to 10 kg of soil) and a control(free of leaf litter).Gas chromatograph-mass spectrometry(GC-MS) was used to identify and compare terpenes existed in the original and decomposed leaf litter.Results showed that:(1)Decomposing leaf litter of camphor tree inhibited the leaf number,leaf area,height and basal diameter of hot pepper sharply,and the inhibition rate increased with the increase of leaf litter.However,in the parallel trial,no significant differences were observed between hot pepper treated with decomposed leaf litter and plastic film in terms of growth status.(2)The numbers of buds,flowers and fruits were all suppressed when exposed to leaf litter during the observation period(45-76 d).Exponential equation was used to fit the budding,flowering and fructification dynamics of hot pepper,and showed that the first bud emerging day,first flower blooming day,and first fruit emerging day were 0.81,0.17 and 1.35 d later than that of control when exposed to 25 g leaf litter,respectively,and those were 4.69,5.78 and 6.27 d later than that of control when exposed to 50 g leaf litter,respectively.More visibly,75 g and 100 g leaf litter both delayed these parameters by more than 10 days.(3)The fruit production of a single plant was inhibited treated with decomposing leaf litter in spite of the doses,with a decreasing amplitude of 29.44%-61.29%,while the single fruit weight was suffered less from the leaf litter.(4)The addition of leaf litter exerted neither significant effect on the 1000-grain weight of the seeds produced by hot pepper,nor on the growth of the progeny.(5)Terpenes represented about 78.05% of the total constituents extracted,and after decomposition,the relative content of which decreased to 40.76%,and most importantly,their absolute peak area decreased to approximately 1% of that in the original sample.The present study revealed obvious suppressive effect of decomposing leaf litter of camphor tree on the vegetative and reproductive growth of the targeted plant.The allelochemicals,e.g.,Camphor and 1,8-cineole released during the decomposition process rather than the alteration of soil and water permeability due to the addition of leaf litter should be responsible for these results.

Abstract:Fine roots played a significant role in exerting the plant functions,soil carbon pool and global carbon recycling.We observed biomass,production and turnover of the fine roots of alfalfa by container method and minirhizotron in the whole growing season that was ranged from June to October in 2013.The result showed that:(1)The inoculated Glomus mosseae (Gm) had the highest mean biomass (12.46 g·m^-2),the control group had the lowest mean biomass (7.31 g·m^-2).The live fine root biomass peaked in mid September,but the dead showed a tendency of increasing first and then declining,and then increasing.In the whole growing process,the dead fine root biomass of non-inoculated was higher than that with inoculated treatment,and inoculated Glomus intraradices (Gi)showed the lowest biomass of dead fine root (3.11 g·m^-2).(2)Inoculated Glomus etunicatum (Ge) had the highest fine root production (0.045 mm·cm^-2·d^-1),Gm and control group had the lowest (0.027 mm·cm^-2·d^-1).However,fine root mortality of non-inoculated treatment (0.044 mm·cm^-2·d^-1) was significantly higher than that with inoculated treatments,and Gi had the lowest fine root mortality (0.021 mm·cm^-2·d^-1).(3)Production and mortality peaks of fine roots appeared at the end of August and October,but trough came in at the end of September to mid October and the end of June to August during the growing reason.The average fine root length and annual length production of Glomus versiforme (Gv) was significantly higher than that of control and other inoculated treatments.Control treatment had the highest fine root turnover,Gv and Gm were the lowest.Inoculating with arbuscular mycorrhizal fungi could improve fine root biomass,reduce mortality and increase the lifespan of alfalfa.

Abstract:Plant species diversity is an index reflecting the complexity and stability of forest community function.Altitude is a prominent factor affecting plant species diversity.In order to investigate the influences of different altitudes on the characteristics of species composition and diversity of Cunninghamia lanceolata plantation in Jiangyou district,Sichuan Province,we conducted a field investigation.Four sample plots were selected in high and low altitude,respectively.The species richness index(D),Shannon-wienner index(H),Simpson index (H′) and Pielou index(J_sw) were adopted to evaluate the level of species diversity in C.lanceolata plantation.The results indicated that:(1)A total of 205 species belonging to 66 families and 177 genera were found in this study area.7 trees,54 shrubs,47 herbs and 10 trees,60 shrubs,41 herbs were included in low and high altitude,respectively.(2)In terms of species composition,the high and low altitude contained similar woody plants.(3)The species diversity at both low altitude and high altitude in different layers of these communities was in a decreasing order of herb layer>shrub layer>tree layer.Species diversity index showed regularity in certain range along with the increasing of altitude.The species D,H and J_sw were demonstrated as high altitude>low altitude;while the H′ was converse.An increasing trend in species diversity and evenness of species distribution at high altitude was found,which may be related to the slight human disturbance and variable environmental factors.

Abstract:Based on field survey data,we studied classification and ordination of Alpine rhododendron community by the methods of TWINSPAN and DCCA,and analyzed distribution pattern of species diversity along the elevation gradient in Qomolangma National Nature Reserve.The results showed that:(1)38 plots included 135 species vascular plants in this Nature Reserve,belonging to 68 genera and 35 families,respectively.The most prevalent species were Kobresia pygmaea,Polygonum viviparum,Euphorbia stracheyi,Rhododendron anthopogon,R.nivale,Cassiope fastigiata,R.lepidotum,Anaphalis xylorhiza and R.setosum.(2)38 plots of alpine rhododendron community were classified into 14 types of plant association.(3)According to two-dimensional DCCA ordination diagram,the soil type and altitude are the main factors of affecting distribution pattern of Alpine rhododendron community in this area.(4)Species richness S,Shannon Wiener index and Simpson index of Alpine rhododendron community declined significantly along the altitude gradient,but there is no significant correlation between Pielou index and altitude in this area.

Abstract:Minqin County is one of the major areas of desertification in China.In this paper,the stability and ecological effects of 5 mainly plant communities were analyzed with 12 years of positioning observations in Minqin desert area.Observations show:Vegetation cover was significantly decreased of Artemisia arenaria and Ephedra przewalskii,and projective cover is significantly decreased of A.arenaria and Haloxylon ammodendron plantation.Vegetation cover of Nitraria tangutorum also decreased.The analysis showed that:(1)Plant community of cover relatively low stability is strong.The plant community of cover relatively high stability is weaker.(2)Year rainfall is the key factor for determining the vegetation cover and the projector cover.(3)Ecological functions of Nitraria tangutorum per unit area is the largest,followed by E.przewalskii,and the third is N.tangutorum+H.ammodendron.Ecological functions of A.arenaria per unit area is the lowest.Vegetation of desert area sparse and plant shoots distribution is extremely irregular.Vegetation cover is calculated with plants crown does not reflect the actual situation of surface covered by vegetation.

Abstract:Betula microphylla is one kind of typical desert and mountain plants trees that distribute only in Xinjiang in China.Inflorescence phenological phase,growth rhythm and set seeds were studied to comprehensively understanding the inflorescence growth phenology and and ecological adaptation of B.microphylla.The results are as follows:The staminate inflorescence of B.microphylla is the two year reproductive organs,whose phenological phase contains 154 days of vegetative growth,158 days of dormancy and 33 days of flowering growth.The pistillate inflorescence and infructescence are annual reproductive organs,whose phenological phase contains inflorescence growing stage of 24 days and infructescence growing stage of 90 days.In spite of the difference of growth cycle between the staminate and pistillate inflorescence,the staminate and pistillate bud burst time appear same in the late in April,exhibiting a centralized pollination mode and result in more seed number and seed rate and higher seed dynamic.As it mentioned above,in a word,B.microphylla can successfully completion of the process of sexual reproduction in the extreme desert environment.

Abstract:ta-siRNA is a class of 21 nt endogenous non-coding small RNA.Its regulatory cascades have been identified as important elements in gene networks involved in the plant phase transition of juvenile-to-adult,development of adaxial-abaxial leaf/flower,and response to biotic and abiotic stresses,and DNA methylation at the TAS locus.In this paper,we reviewed the advances of ta-siRNA regulatory cascades,including its discovery,function,types and identification,and also discussed its present problems and furture research prospects.We hope the review could provide a useful reference for ta-siRNA research and utilization.