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Table of Content

    10 November 2007, Volume 40 Issue 11
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES
    Genetic effect of japonica alleles detected in indica candidate introgression lines
    Scientia Agricultura Sinica. 2007, 40(11):  2387-2394 . 
    Abstract ( 1076 )   PDF (462KB) ( 1089 )   Save
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    【Objective】To accurately assess genetic effect of alleles from japonica in a genetic background of indica and to efficiently utilize inter-subspecific heterosis between indica and japonica. 【Method】We have developed a set of novel population with 88 candidate introgression lines (ILs) through backcross program and marker-aided selection, which using japonica variety Nipponbare as donor and indica variety Zhenshan97B as recurrent parent. Each of the ILs contains single one or few japonica introgression segments within the uniform indica genetic background, and together all the introgression segments can cover the whole japonica genome. The genetic effects of each introgression segment in the 88 ILs were analyzed on yield and its component traits including number of tillers, grains per panicle and 1000-grain weight. 【Results】Twenty nine quantitative trait loci (QTLs) with significant effects were detected, of those 6 QTLs had positive additive and overdominant effects, 23 QTLs had negative additive and overdominant effects. 【Conclusion】 Some favorable alleles from japonica could increase yield or its components in the indica background. The overdominant effects play important role in heterosis of intersubspecies.
    Characterization, Function and Expression Analysis of Ammonium TransporterGene OsAMT1;4 and OsAMT5 in Rice (Oryza sativa)
    Scientia Agricultura Sinica. 2007, 40(11):  2395-2402 . 
    Abstract ( 1339 )   PDF (934KB) ( 1113 )   Save
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    【Objective】To elucidade the characterization, function and expression pattern of two ammonium transporter genes OsAMT1;4 and OsAMT5 in rice (Oryza sativa). 【Method】The characterization of the encoded proteins by OsAMT1;4 and OsAMT5 was identified based on bioinformatics technology. The complementary analysis of function on NH4+ uptake for OsAMT1;4 and OsAMT5 was performed by genetic transformation of the yeast mutant lacking the ability of transporting NH4+. The gene expression patterns of OsAMT1;4 and OsAMT5 were analyzed by RT-PCR. 【Results】OsAMT1;4 and OsAMT5 had the open reading frame (ORF) 1497 bp and 1377 bp, encoded 498 amino acids and 458 amino acids, respectively. OsAMT1;4 and OsAMT5 belonged to AMT1 and AMT2 sub-family, all containing 11 conserved transmambrane domains, and could recovery the mutant lacking the ability of transporting NH4+ to re-uptake NH4+ in the growth medium, The transcripts of OsAMT5 were only in leaves and the expression levels were increase with the increase of NH4+ concentration in the medium, In all treatments, the transcripts of OsAMT1;4 in roots and leaves were all not detected.【Conclusion】OsAMT1;4 and OsAMT5 are involved in the uptake or transportation of NH4+ in the plants of rice. OsAMT5 is leaf specific in expression under NH4+ treatments. The expression of OsAMT1;4 is possibly regulated by other environmental conditions, rather than by NH4+.
    Sequencing and analysis of HMW glutenin subunit gene Tibetan Dy10 in a novel subunit combination of Tibetan Dx5*+Tibetan Dy10 in Tibetan wheat landrace
    Scientia Agricultura Sinica. 2007, 40(11):  2403-2408 . 
    Abstract ( 1460 )   PDF (399KB) ( 887 )   Save
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    Sequencing and analysis of HMW glutenin subunit gene Tibetan Dy10 in a novel subunit combination of Tibetan Dx5*+Tibetan Dy10 in Tibetan wheat landrace YAN Ze-hong, DAI Shou-fen, LIU Deng-cai, WEI Yu-ming, ZHENG You-liang Triticeae Research Institute, Sichuan Agricultural University, Dujiangyan City, Sichuan province, China, 611830 Abstract: [Objective] The objective of this study is focus on elucidating the main difference between HMW glutenin subunit gene Tibetan Dy10 in a novel HMW gluenin subunit combination of Tibetan Dx5*+Tibetan Dy10 in Tibetan wheat landrace and Dy10 in subunit combination of Dx5+Dy10 at molecular sequence level. [Method] The SDS-PAGE analysis, cloning and sequencing method were used. [Result] The result indicated that the molecular sequence of HMW glutenin subunit gene Tibetan Dy10 was very similar to that of Dy10 in HMW glutenin subunit combination Dx5+Dy10. The difference is that one amino acid in each of the two hexpeptide repetitive motifs in Dy10 has been substituted in Tibetan Dy10, respectively. [Conclusion] Thought minor differences were found between Tibetan Dy10 and Dy10, there still have the reason that Tibeatan Dy10 is a Dy10 but not others. Keywords: Tibetan wheat landrace; a novel HMW glutenin subunit combination; y-type HMW glutenin subunit; Sequencing
    Relationship and QTL Mapping of Ear Traits under N-Stress Condition in Maize
    Scientia Agricultura Sinica. 2007, 40(11):  2409-2417 . 
    Abstract ( 1223 )   PDF (523KB) ( 1223 )   Save
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    Ear traits are most important factors in yield components.In this investigation,six ear traits including ear length(EL), ear diameter(ED),ear row number(ERN),row kernel number (RKN),grain yield per ear(GY) and 100 kernel weight(KW), had been analyzed using a population with 203 F2:3 families derived from an elite maize(Zea mays L.) cultivar Nongda 108(Huang C×Xu 178), field trials were conducted under nitrogen input (N+) and stress( N-) conditions in Zhengzhou and Xinzheng in 2004, the linkage map including 189 SSR markers covering the 10 chromosomes of maize and the Composite Interval Mapping(CIM) method were used to localize the quantitative trait Loci of ear traits. The results showed that N- stress had more influence to the parent Huang C than to Xu 178. Correlation analysis indicated that EL, ED,ERN and RKN were mainly significant/highly significant positive correlation with GY. Through 1000 times permutation test to have proper LOD threshold values for ear traits, total of 53 QTLs were identified under N+ and N- conditions in two locations. The 28 QTLs detected in Zhengzhou mainly clustered in chromosome 2,8 and 9(occupied by 57.14%),while the 25 QTLs identified in Xinzheng mainly clustered in chromosome 1,2,6,7 and 8 (occupied by 60%). Among the 53 QTLs, 13(24.53%)QTLs appeared to be additive, 20(37.74%)partial dominance , 6(11.32%)dominance and 14(26.42%) over- dominance , the phenotype variation explained by a single QTL varied from 7% to 23%. Only 3 QTLs(qED2a,qKW8a,qKW10a)were both detected under the two nitrogen levels in Zhengzhou,and 1 QTL(qEL1a) both detected in Xinzheng,While only 2 QTLs(qRKN8b,qGY1a) detected at both sites. However,the rest QTLs located in different chromosome or different position on the same chromosome. The QTLs of all traits identified only under low nitrogen stress condition might be relation with nitrogen high use efficiency in maize.
    Progress on Related Fields of Soybean Molecular Breeding in China
    Scientia Agricultura Sinica. 2007, 40(11):  2418-2436 . 
    Abstract ( 1399 )   PDF (470KB) ( 2148 )   Save
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    Expression of TrxS and its Effect on Amylase Activities of Barley Seeds
    Scientia Agricultura Sinica. 2007, 40(11):  2437-2442 . 
    Abstract ( 1401 )   PDF (372KB) ( 863 )   Save
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    The paper analyzed the expression of TrxS gene and its effect on amylase activities of barley seeds during germination period, the results showed that TrxS gene could express in transgenic barley seeds by the detection of real-time PCR. During germinating days 1-5d, the activities ofα- amylase were 5.86%、75.24%、118.51%、71.02%、22.99% higher than that of none-transgenic seeds, respectively; the activities ofβ- amylase were 19.29%、14.68%、35.47%、23.62%、2.67% higher than that of none-transgenic seeds, respectively; the germination vigor of transgenic seeds was higher than that of none-transgenic seeds, either. The results provided theoretical basis for the regulation of seed metabolism.
    TILLAGE & CULTIVATION·PHYSIOLOGY & ECOLOGY
    Effect of Free-air CO2 Enrichment (FACE) on Grain Filling Properties of Rice
    Scientia Agricultura Sinica. 2007, 40(11):  2443-2451 . 
    Abstract ( 1467 )   PDF (323KB) ( 1120 )   Save
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    【Objective】 In order to investigate the effect of atmospheric CO2 concentration ([CO2]) on grain-filling properties of rice. 【Method】Using the unique free-air CO2 enrichment (FACE) system in China, a japonica rice cv. Wuxiangging 14 was grown at ambient or elevated (ca 200 μmol mol-1 above ambient) [CO2] under three levels of N: low (LN, 150 kg hm-2), medium (MN, 250 kg hm-2) and high N (HN, 35 kg hm-2). Grain filling dynamic at different positions of rice panicle was investigated. The Richards equation was used to describe grain filling processes. 【Result】(1) Under LN condition, FACE treatment increased grain weight significantly, averaging 9.9%, 7.0% and 7.7% for grains on upper, middle and low parts of the panicle, respectively. However, no effect of FACE was observed under HN and MN conditions. (2) In general, FACE treatment enhanced the initial relative growth power (GR0/W0) of grains on different parts of the panicle. (3) FACE treatment greatly increased the maximum grain-filling rate (MRm), averaging 38.6%, 24.3% and 38.6% for LN-, MN- and HN-plants, respectively, with CO2-induced increase being larger for upper grains than middle and low ones on the panicle. In addition, the mean grain-filling rate (MGR) was enhanced due to FACE by 38.9%, 47.7% and 44.1% for LN-, MN- and HN-plants, respectively. (4) Overall, grains of FACE plants had later time to reach maximum growth rate, heavier grain weight at time when the growth rate is maximum and shorter mean grain-filling duration as compared with those of ambient plants. As for different grain-filling stages, FACE treatment obviously prolonged the duration of early grain-filling stage, while the duration of middle and late grain-filling stages showed the opposite trends.【Conclusion】These data indicated that FACE treatment increased the GR0/W0, GRm and MGR, prolonged the duration of early grain-filling stage with a shortening of duration of middle, late and whole grain-filling stages. FACE treatment greatly increased grain weight of different panicle positions under LN condition, whereas no significant changes were observed under MN and HN conditions.
    Gray Relational Grade Analysis of Agronomical Characters and Physi-biochemical Indexes Related to Drought Tolerance in Wheat
    Scientia Agricultura Sinica. 2007, 40(11):  2452-2459 . 
    Abstract ( 1260 )   PDF (421KB) ( 1452 )   Save
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    【Objective】This paper aims to probe the relationship between agronomical characters and physi-biochemical indexes of wheat cultivar with its drought tolerance. 【Method】 12 indexes, including 5 agronomical characters and 7 physi-biochemical indexes that measured in 65 wheat cultivars grown at drought shelf and no-irrigation conditions, were analyzed using gray relational grade analysis method. 【Result】 Gray correlation degrees facilitating to identify the drought tolerance of wheat were calculated between each index and its drought resistance index, they were ranked as follows by their contribution to drought tolerance: stomata conductance (γ=0.7995), photosynthetic rate (γ=0.7909), transpiration rate (γ=0.7556), soluble sugar content (γ=0.7467), MDA content (γ=0.7336), dissociative proline content (γ=0.7267), spike length (γ=0.7102), number of kernel per spike (γ=0.7095), 1000-kernel weight (γ=0.7005), water potential (γ=0.6959), tiller (γ=0.6951), plant height (γ=0.6866). And the clustering analysis based on the weighted drought index of cultivars could finely represent their breeding and application areas. Species that have the best drought resistance among the 65 species are: Luohan 6, Xiaoyan 6, Jinmai 47, Shanmai 168 etc. 【Conclusion】 The result indicates that the physi-biochemical indexes related to leaf stomata have the closest relationship with the drought resistance of wheat, and these indexes are significantly influenced under water stress, thus have the greatest relation degree with drought resistance index, so the physi-biochemical indexes including stomata conductance, photosynthetic rate and transpiration rate should be used for the assistant selection of drought tolerance to improve the selection efficiency.
    Canopy and Yield Characteristics of Super-High-Yielding Soybean Liaodou14
    Scientia Agricultura Sinica. 2007, 40(11):  2460-2467 . 
    Abstract ( 1236 )   PDF (489KB) ( 1005 )   Save
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    Abstracts: 【Objective】Super-high-yielding soybean had certain advantages in plant type characteristics. This study investigated the morphological and physiological characteristics of super-high-yielding soybean Liaodou14. 【Method】Comparative analysis of plant type characteristics were carried out through multi-year experiments with super-high-yielding soybean Liaodou14 and general soybean Liaodou11 as varieties. 【Result】The chlorophyll content and photosynthetic rate of L14 from seedling to full podding were not superior to L11, but higher obviously after full podding. When the photosynthetic rate of different nodes was tested, it was found that the difference of photosynthetic rate between upper layer and lower layer was smaller and the leaves of lower layer senesced slower for super-high-yielding soybean. The distribution of petiole length and LSI (leaf shape index) of L14 were more reasonable, which made it intercept more sunlight at higher LAI. The LAI and photosynthetic rate of L14 maximized later than L11, but had a longer duration and descended slower in late stage. The accumulation of biological yield of L14 was smaller before podding, but higher than L11 after podding. After podding, L14 transported more photosynthetic products to pods, which made it got higher HI. 【Conclusion】The main reason why super-high-yielding soybean L14 got higher yield was that from full podding to late pod-filling, it had better canopy structure, maintained higher LAI and photosynthetic potential and had higher photosynthetic productivity.
    Tobacco plants transformed with Sweet Pepper positive GPAT Gene Alleviate Photoinhibition Under High Temperature
    Scientia Agricultura Sinica. 2007, 40(11):  2468-2473 . 
    Abstract ( 1350 )   PDF (415KB) ( 1108 )   Save
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    The saturated extent of MGDG, SQDG, DGDG and PG in thylakoid membrane of tobacco plants transformed with sweet pepper positive GPAT gene increased entirely, remarkably in MGDG with increasing by 16.2%. Under high temperature stress (48℃), ΦPSⅡ and Fv/Fm of wild type tobacco plants decreased by 42.3% and 21.3%, but only decreased by 24.2% and 13.7% in transgenic tobacco, which indicated that the transformed tobacco plants maintained higher actual photochemistry efficiency of PSII and lower photoinhibition under high temperature. The increase in saturated extent of thylakoid membrane lipids raised the temperature inducing phase separation and enhanced the stability of PSⅡunder high temperature.
    PLANT PROTECTION
    Sequencing and analysis of Rice gall dwarf virus genome segment 6
    Scientia Agricultura Sinica. 2007, 40(11):  2474-2480 . 
    Abstract ( 1012 )   PDF (316KB) ( 422 )   Save
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    【Objective】In order to understand the whole genome organization and its functions of Rice gall dwarf virus (RGDV), we got the complete sequence of RGDV genome segment 6. 【Method】Four rounds of RT-PCR were performed according to the property of segment-specific reverted repeat termini sequences reported. Sequences were analyzed by using bio-software. 【Result】The full-length cDNA of S6 was 1 651 bp with 39.13% G+C content, containing a single open reading frame (ORF) that extends 1473 nucleotides from nucleotide 25. The single ORF encoded a putative 53.3 kDa polypeptide, named Psn6, containing 490 amino acids. 【Conclusion】 RGDV Psn6 exhibited 31.7% amino acid sequence identity to P7 of Rice dwarf virus (RDV), and 30.0% to P7 of Wound tumor virus (WTV). This is the first report of the complete sequence of RGDV S6.
    Dynamics in kanamycin-resistant bacterial population and shift of nptII gene in the phyllosphere of insect-resistant transgenic cotton
    Scientia Agricultura Sinica. 2007, 40(11):  2488-2494 . 
    Abstract ( 1132 )   PDF (453KB) ( 1055 )   Save
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    【Objective】To study the Dynamics in kanamycin-resistant bacterial population and monitor shift of nptII gene in the phyllosphere of insect-resistant transgenic cotton.【Method】Insect-resistant transgenic cotton 33B, SGK321 and GK12,and corresponding receptor cotton 33, Shiyuan 321 and No.3 Simian cotton were sampled at different growing stages. Dynamics and diversity among kanamycin-resistant bacterial populations in the phyllosphere were analyzed with the conventional culture methods. In addition, the shift of nptII gene was monitored by germ PCR, and the unique primer was designed from the sequence of nptII gene, the CK is pBI121 plasmids.【Result】at different sample time,significant differences were found among the total number and diversity index of phyllospere kanamycin-resistant bacterial population each cotton variety, but little differences between Insect-resistant transgenic cotton and corresponding receptor cotton at the same time. we discovered the positive segment from kanamycin-resistant bacteria in the phyllosphere of insect-resistant transgenic cotton SKG321, GK12 and receptor cotton No.3 Simian cotton.【Conclusion】We suggested that little differences were found among the total number and diversity index of phyllospere kanamycin-resistant bacterial population between Insect-resistant transgenic cotton and corresponding receptor cotton,and nptII gene in insect-resistant transgenic cottons could drift into the phyllosphere bacteria.
    The Establishment of Rapid Detection Method for the Pathogen of Hami Melon Fruit Blotch
    Scientia Agricultura Sinica. 2007, 40(11):  2495-2501 . 
    Abstract ( 1171 )   PDF (504KB) ( 1160 )   Save
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    【Objective】Hami melon bacterial fruit blotch (HBFB) is a new disease in China, the pathogen is Acidovorax avenae subsp. citrulli, which damages the fruits and lowers their qualities. HBFB is a typically seedborne bacterial disease, and the important prevention and cure method is the quarantine of the seeds with bacteria.【Method】and【Result】In this study, the immuno-detection was combined with PCR by using the superparamagnetic beads to form IMS-Realtime-PCR, which increase the precision of bacteria detection to app. 3×102 CFU/ml. The integrated method of bacterial detection was formed through combining the ASCM culturing, IMS and real-time PCR. 【Conclusion】One seed with bacteria in 1000 seeds could be detected using this integrated method.
    The potential geography distribution of Radopholus similis in China
    Scientia Agricultura Sinica. 2007, 40(11):  2502-2506 . 
    Abstract ( 1263 )   PDF (223KB) ( 1123 )   Save
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    【Objective】 The burrowing nematode (Radopholus similis) is one of the main quarantine pests in China and the risk of invasion posed by this nematode is becoming more and more serious with regard to the international trade being intensified day by day. It is urgent to analysis the potential geography distribution of R.simils in China. 【Method】GARP and MAXENT, the two niche models, have widely been used to predict the potential geographic distribution of alien species. This paper made a prediction of the distribution of R.similis in China using GARP and MAXENT models and also gives a model comparison of the results by both of threshold-dependent and threshold-independent test. 【Result】 It has shown that the two niche models could be used to predict the potential distribution of R.similis reliably. The potential distribution of R.similis should be constricted within the south of China, such as Hainan, Guangdong, Fujian, Yunnan and Taiwan provinces/areas according to the results predicted by using the two niche models. It has also convinced the MAXENT gives a better prediction result than that of GARP. 【Conclusion】R.similis can introduced to our country by the flower and nursery stock's international shipping. The predicted results indicate that R.similis can occur in south coast area of China and Yunnan province, the main flower and nursery stock's import-export area of China. So it requires that the quarantine measures of the ports of such areas should be strengthened.
    SOIL & FERTILIZER·WATER-SAVING IRRIGATION
    Heavy Metal Content in Soils of Chinese Vegetable Land and Source Analysis
    Scientia Agricultura Sinica. 2007, 40(11):  2507-2517 . 
    Abstract ( 1637 )   PDF (360KB) ( 1553 )   Save
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    【Objective】The objective was to study the content of heavy metals in soils of vegetable lands systematically through assessment objectively to promote the development of vegetable production with high quality and efficiency. 【Methods】Statistical analysis of reported data on the heavy metals in Chinese vegetable plantation soils, from previous literature published since 1989, was carried out systematically in this investigation.【Results】 It is concluded that Zn, Cr, Cu had relatively high concentrations while the mean concentrations of toxic metals, As, Hg, Cd was 8.03、0.12、0.28mg•kg-1 separately with comparatively low concentrations in Chinese vegetable land. Comparing to Chinese Soil Quality Criterion GB 15618-1995 (6.5 Hg > As> Zn > Cu > Cr > Pb. When compared among different regions, the relatively serious heavy metal contamination was found in the eastern China vegetable land and the main contamination elements were Cd、Hg、Zn as well as As in some extent. In the mid region, vegetable plantation soil was mainly polluted by As and Cd. In the meanwhile, Cd, Cu and As contamination was also observed in some degree in the west region of China. Comparing to the five vegetable plantation land patterns, the highest concentration of As, Cd, Hg and Zn occurred in the industrial/sewage irrigation vegetable land, especially for Hg with 2.36mg•kg-1 content averagely which is 10.5~21.1 times higher than other four types of vegetable lands. The highest concentration of Cu and Cr occurred in greenhouse vegetable land soils, and urban vegetable land soil had the highest Pb content comparing to other types of vegetable plantation land patterns. Through analyzing heavy metal content under different vegetable land pattern, it was found that vegetable producing base soil had relatively low heavy metal concentrations except for Pb with a little higher amount in surburb. The soil quality of common vegetable land was good with the lowest concentrations for most heavy metals. 【Conclusion】Under present utilization patterns of vegetable land, the soil quality in Chinese vegetable base land was good with comparatively low concentrations of heavy metals and mostly not exceeding the grade II level of Chinese Soil Quality Criterion GB 15618-1995 (6.5
    Comparison Micromorphological Features of Two Agriculture Cultivated Soils in Guanzhong Areas, Shaanxi
    Jiang-li PANG
    Scientia Agricultura Sinica. 2007, 40(11):  2518-2526 . 
    Abstract ( 1490 )   PDF (521KB) ( 891 )   Save
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    【Objective】To compare micromorphological features of both irrigated and non-irrigated soil in Guanzhong Areas, this paper try to illustrate farming method influences on soil-forming process of soil.【Method】Micromorphology is observed under a petrographic microscope and its image is quantificationally measured by Qwin3.1 software. 【Result】 Both irrigated soil and non-irrigated soil have the same as soil profile type,Ap1- Ap2- BC, but the former has a more obvious profile difference. The minerals assemblage of different horizon is very similar, which is mainly composed of Q and Pl. Compared with non-irrigated soil, coarse of irrigated soil is characterized by Length, Area, EqDiameter, Perimeter, Elongation, Roundness, MeanChord and C/F(10μm) ratio; voids are characterized by more regular void shape and more smooth void wall; there are more abundant residual clay and little amount illuvial clay. 【Conclusion】All the results in this study suggest that farming method has the influence on the soil profile difference and micromorphology. The agriculture irrigating could strengthen the degree of weathering, making smaller and rounder coarse, increasing quantities of residual clay and appearing illuvial clay, no-changing minerals assemblage of coarse.
    Study on the Effect of Different Nitrogen Rates Under Spring Cabbage-Maize-Winter Cabbage Rotation System
    Scientia Agricultura Sinica. 2007, 40(11):  2527-2534 . 
    Abstract ( 1224 )   PDF (239KB) ( 948 )   Save
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    The field trials were conducted to study the effect of different rates of nitrogen under spring cabbage-corn-winter cabbage rotation system .The results indicated that: the 0-60cm soil section inorganic N content remarkable influence the maximum N fertilizer rate to obtain the maximum yield of spring cabbage, winter cabbage, when the section inorganic N content is 142.2 kg/hm2, the spring, winter Cabbage N fertilizer rate to obtains the maximum yield were 236.2kg/hm2, 311.4 kg/ hm2 respectively; When the section inorganic N content is 244.0 kg/ hm2, the value were 174.2kg/ hm2, 296.5 kg/ hm2. The local custom N fertilizer rate was 1.8-3.2times that N fertilizer rate to obtain the maximum cabbage yield ,excess application N rate has caused NO3-N rich in the ground water. The N fertilizer rate and soil profile inorganic N content affects cabbage the N utilize rate, the cabbage -corn rotation system is advantage to enhancement the N utilize rate. Right amount N rate(90kg/ hm2) is simultaneously enhance the yield and the quality of Cabbage; When the N rate further enhances, the cabbage yield also may further enhance, but the quality drops; When the N rate is excessively high, then both the yield and quality of cabbage decrease. Thus to obtain the better quality vegetables in the production, must reduce the N fertilizer rate and cabbage yield.
    Effects of N rate on application rate on N utilization and yield of vegetable and soil residual NO3--N under drip irrigation system
    Scientia Agricultura Sinica. 2007, 40(11):  2535-2545 . 
    Abstract ( 1440 )   PDF (493KB) ( 870 )   Save
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    【Objective】The effects of different application nitrogen treatment were studied on soil NO3--N accumulation and Nitrate leaching in different soil depth in Ningxia yellow river irrigated area. The anniversary vegetable yield and nitrogen balance of tomato-tomato-cucumber-tomato growing system were estimated. as The purpose was to provide a firm foundation for better reasonable nitrogen application of tomato-tomato-cucumber-tomato growing system under drip-irrigation condition of greenhouse in the area.【Method】The representative tomato and cucumber were chose in the area. A method with field experiment and chemical analysis was carried out .To compared with CK and Organic fertilizer ,the effects of different application nitrogen treatment were studied on the nitrogen balance, nitrate accumulation and leaching with tomato-tomato-cucumber-tomato growing system under drip-irrigation condition in greenhouse in Ningxia yellow river irrigated area from 2004 to 2006. 【Result】 Preceding two season ‘s tomato yield and total assimilated N were not increased in convention application nitrogen and high application nitrogen treatment, but medium and low of two application nitrogen treatment maintenance upper yield. After two season’ vegetable, with the increasing application nitrogen, vegetable’s yield and total assimilated N were increased in decreased application nitrogen condition. After any season vegetable harvesting, all of nitrate accumulation was very high with middle or high nitrogen rate. The NO3--N accumulation amount in 0~90 cm were 73%~75% in total NO3--N accumulation amount in 0~180 cm.. With decrease application nitrogen amount, the soil NO3--N accumulation 177.1~651.6 kg•ha-1 was reduced 15.8~50.5 kg•ha-1 from the first season to fourth season in different treatment, but then content NO3--N of soil solution were leaching in the main 60~90 cm depth. The application nitrogen and irrigation water were main place in nitrogen input, the nitrogen input was increasing significantly with nitrogen fertilizer increasing. The soil Nminresidue was main place in nitrogen output, shoot nitrogen uptake (697.7~882.1 kg•ha-1) of each season vegetable didn’t increase significantly with nitrogen input increasing, therefore, which caused soil Nmin accumulation a lot with high nitrogen rate. 【Conclusion】Some factors of nitrogen balance, nitrate accumulation and nitrogen balance were discuss, reduced nitrogen fertilizer was feasible with tomato-tomato-cucumber-tomato growing system under drip-irrigation condition in the area. The based on Organic fertilizer rate 、 phosphor nitrogen fertilizer and potass fertilizer rate condition, the nitrogen fertilizer rate was about 100~150kg•ha-1 under autumn-winter season ‘s tomato, the nitrogen fertilizer rate was about 250~300kg•ha-1 under winter-spring season’s tomato, the nitrogen fertilizer rate was about 400~450kg•ha-1 under autumn-winter season's cucumber. As result maintain vegetable’s yield and satisfaction above nitrogen demand did not cause environmental threaten.
    Response of cotton growth and water use to different partial root zone irrigation
    Scientia Agricultura Sinica. 2007, 40(11):  2546-2555 . 
    Abstract ( 1063 )   PDF (617KB) ( 690 )   Save
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    【Objective】The objective of this study is to evaluate the effect of alternate partial root zone irrigation on taproot crop growth and its water use. 【Method】Potted cotton (Gossypium hirsutum cv Shaan 392) experiment was conducted in green house to investigate the response of growth and water use of with three partial root zone irrigation patterns i. e., alternate partial root zone irrigation (APRI), fixed partial root zone irrigation (FPRI) and whole root zone irrigation.【Result】The results showed that APRI reduced ‘luxury’ transpiration without much reduction in photosynthesis rate by slightly limiting stomatal opening. Leaf water potential showed that cotton under APRI had more ability of osmotic regulation to maintain higher leaf turgor. 【Conclusion】It suggested that APRI has great potential to save water and also maintain the balance between vegetative and reproductive growth with reduced redundancy growth. It regulated the distribution of photosynthesis products and ratio between root and shoot. Meanwhile, the compensating effects of root growth and hydraulic conductivity were also observed
    HORTICULTURE
    Responses to Nitric Dioxide Stress and Modulation of Hydrogen Peroxide in Pakchoi Seedlings
    Scientia Agricultura Sinica. 2007, 40(11):  2556-2562 . 
    Abstract ( 1015 )   PDF (398KB) ( 720 )   Save
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    Abstract 【Objective】This paper investigated the responses of Pakchoi seedlings to acute level of nitric dioxide (NO2) exposure, examined whether pre-treating plants with hydrogen peroxide (H2O2) would alleviate NO2-induced injury and discussed the possible role of H2O2 in the modulation of some physiological and biochemical characteristics of the plants.【Method】Some indices were determined in Pakchoi seedlings sprayed with H2O2 solution and untreated control plants, both exposed to NO2 for 24 h under controlled environment. To measured the biomass, plants were pretreated with H2O2 for 1 day and then exposed to NO2 stress 7 h per day for 7 days.【Result】A low concentration of NO2 has a favorable effect on plants, and the growth was promoted. On the other hand, plants exposed to a high concentration of NO2 (1 μl•L-1 and above in this experiment) caused visible symptoms. A reduction of growth and chlorophyll content, and increase of malondialdehyde (MDA) content were occurred in plants exposed to 1 μl•L-1 or above of NO2, compared with the control. Other changes in plants responsed to NO2 stress included appeared necroses on older leaves, increased antioxidative enzymes, superoxide dismutase (SOD) and catalase (CAT) activities, decreased ascorbate (ASA) content, higher accumulated NO3-, induced nitrate reductase (NR) activity and impaired photosynthesis, but no detected change in stomatal conductance. The unfavorable influences of NO2 stress to plants were significantly alleviated on pretreatment with 10 mmol•L-1 of H2O2, as indicated by recovery of plant fresh weight, ASA and MDA contents to the control levels. The photosynthetic rate was obviously recovered. More induction of SOD and CAT activities has been observed in H2O2 – treated plants. However, H2O2 treatment did not alter the responsiveness in nitrate content and NR activity. H2O2 pretreatment resulted in a lower rate of stomatal conductance.【Conclusion】Together, these data indicate that acute stress of 1 μl•L-1 and above of NO2 caused visible injury to Pakchoi seedlings, which may be related to oxidative damage confered by impaired photosynthesis. H2O2 pretreatment alleviates NO2-generated injury to plants, which may be related to induction of antioxidative system in the plant.
    Polyphenolic compound and Degree of browning in Processing Apple Varieties
    Scientia Agricultura Sinica. 2007, 40(11):  2563-2568 . 
    Abstract ( 1143 )   PDF (359KB) ( 938 )   Save
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    【OBJECTIVE】Polyphenolic compound in processing apple (Malus domestica Borkh.)varieties and the relationship between polyphenol content and enzymatic browning were studied in order to provide reference for raw material selection and processing method optimization.【METHOD】The content of polyphenol compound in 10 processing apple varieties (4 cider and 6 juice varieties) were analyzed by Folin-Ciocalteu method and HPLC. Degree of browning and acitivities of polyphenol oxidase were also studied.【RESULTS】The content and proportion of the polyphenol varied depending on varieties. Bitter varieties globally showed a higher polyphenol concentration than sweet or acid varieties. Proanthocyanidins, chlorogenic acid, (+)-catechin, (-)-epicatechin were high-concentrated polyphenols in apple fruits. Phloridzin, the unique polyphenol of apple, was abundant in bitter variety Frequin rouge fruit. Total polyphenoics, proanthocyanidins, (+)-catechin, and phloridzin had higher correlations with browning. The correlation was low between chlorogenic acid and browning.【CONCLUSION】The polyphenolic profiles were correlated with apple types. Cider apples contained more phenolics than juice apple varieties. The content of flavan-3-ol has close relationship with fruit browning.
    Predicting the Leaf Area of Greenhouse Single Flower Cut Chrysanthemum
    Yangzai-qiang
    Scientia Agricultura Sinica. 2007, 40(11):  2569-2574 . 
    Abstract ( 1028 )   PDF (406KB) ( 866 )   Save
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    【OBJECTIVE】A model for predicting the leaf area of single flower cut chrysanthemum was developed for optimising greenhouse single flower cut chrysanthemum production management.【METHOD】Based on the effects of temperature and radiation on chrysanthemum leaf emerging and elongation, experiments with different varieties and planting dates were carried out in greenhouses to collect data to develop and validate the model.【RESULTS】The predicted results agreed well with the observed ones. The determination coefficient (R2) and the root mean squared error (RMSE) between the predicted and the measured leaf area index (LAI) based on the 1:1 line are 0.94 and 0.75, respectively. Compared to the models based on growth degree days (GDD) and specific leaf area (SLA), the prediction accuracy of the model developed in this study is 48.2% and 84.6% higher, respectively.【CONCLUSION】From the results obtained in this study, it can be concluded that the model developed in this study can give satisfactory prediction of the leaf area index of greenhouse single flower cut chrysanthemum and can be used for the prediction of biomass production and production management of single flower cut chrysanthemum.
    Changes of Chemical Bonds during Peanut Protein High Moisture Extrusion Texturization
    Scientia Agricultura Sinica. 2007, 40(11):  2575-2581 . 
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    Abstract: 【Objective】The effects of extrusion temperature on the microstructure of extrudates, protein solubility in 5 solvents, total sulphhydryl and disulfide bonds contents of extrudates were investigaged, and the effects of succinylated modification before extrusion on the structures and rheology properties of extrudates were also discussed in this paper, and aimed to grope for the mechanisms of peanut protein high moisture extrusion texturization. 【Method】The microstructures of extrudates observed by scanning electron microscope, the rheology properties of extrudates analysed by texture profile analyzer, and the conventional chemical methods were used to determined the total sulphhydryl and disulfide bonds contents of extrudates and succinylation of peanut protein. 【Result】(1) The solubility of peanut protein was greatly decreased with extrusion temperature increasing, but the protein solubility obviously increased when buffer contained sodium dodecyl sulphate (SDS), alone or combination with 2-mercaptoethanol (2-ME); The changes of total sulphhydryl contents among extrudates were not significant, disulphide contents of extrudates slightly decreased at 140-150℃, and decreased significantly at 155℃. (2)The hardness, chewiness and texturized degrees of extrudates were significantly decreased with peanut protein succinylated modification before extrusion. The microstructure of extrudates identified the changes of the rheology properties.【Conclusion】(1) Hydrophobic interactions and hydrogen bonds played the main function, and disulphide bonds was the second during peanut protein texturization. (2) Disulfide bonds in peanut protein molecules were cleaved during extrusion, and the higher temperature could accelerate this reaction. (3) Succinylated modification could disturbed the interactions between protein molecules and hindered the fibrous structure formation during extrusion texturization.
    Effects of Nitric Oxide on Biosynthesis and Physiological Action of Ethylene in Feicheng Peaches
    Scientia Agricultura Sinica. 2007, 40(11):  2582-2586 . 
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    【OBJECTIVE】The effects of nitric oxide (NO) and exogenous ethylene on ethylene biosynthesis in ‘Feicheng’ peaches were studied. The effect of NO on the physiological actions of exogenous ethylene was explored.【METHOD】‘Feicheng’ peaches were fumigated with 10 μl·L-1 NO, 1000 μl·L-1 ethylene, separately or 10 μl·L-1 NO and 1000 μl·L-1 ethylene. The changes of ethylene biosynthesis in ‘Feicheng’ peach fruit were studied【RESULTS】The exogenous ethylene promoted the biosynthesis of endogenous ethylene in peach fruit. The treatment with NO reduced significantly the activities of ACS and ACO, and inhibited remarkably the biosynthesis of ethylene in fruit. The ethylene biosynthesis in fruit treated with NO and exogenous ethylene was lower than treatment with exogenous ethylene, but higher than the treatment with NO. This suggested that NO inhibited significantly the physiological actions of ethylene. NO could react directly with the metal center of ethylene receptor, change the electron cloud density and the spatial structure of ethylene receptor, and prevent the binding of exogenous ethylene to receptor. NO could also deoxidize the Cu2+, the cofactor of ethylene receptor, to Cu+. Although exogenous ethylene could bind with receptor, Cu+ could not activate the receptor. As a result, ethylene could not exert its physiological effects.【CONCLUSION】NO could inhibit the biosynthesis and physiological effects of ethylene, and retard the physiological actions of exogenous ethylene.
    The Influence of Red Wine and Alcohol-free Red Wine
    Scientia Agricultura Sinica. 2007, 40(11):  2587-2592 . 
    Abstract ( 1067 )   PDF (573KB) ( 1003 )   Save
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    To study the protective effect and mechanism of red wine and alcohol-free red wine on risk of atherosclerosis. This experiment was conducted on 50 male golden hamsters, which were divided into five groups, each of which contained 10 hamsters: red wine group, alcohol-free red wine group, alcohol group, hyperlipidemia group and control group. During 4 weeks, all hamsters were fed high cholesterol diets except control group. Afer completion of the trial, the plasma lipid levels and lipid peroxidation contents were determined in golden hamsters, and the morphological variation in liver cell was investigated with electron microscopy. The results showed red wine, alcohol-free red wine and alcohol decreased significantly the concentrations of TC and TG in hamsters. Compared with the hyperlipidemia group, the levels of LDL-C were significantly decreased in other groups, but not the HDL-C. Consumption of red wine, alcohol-free red wine and alcohol, all had no significant effects on ApoⅠand ApoB. Red wine, alcohol-free red wine and alcohol significantly decreased the contents of MDA in hamsters. The experiment demonstrated red wine can ameliorate the incidence of atherosclerosis by reducing serum TC, TG, LDL-C, and compounds of red wine have co-operative effect.
    ANIMAL SCIENCE·VETERINARY SCIENCERE·SOURCE INSECT
    Expression and characterization of Porcine Epidermal Growth Factor in Pichia Pastoris
    Scientia Agricultura Sinica. 2007, 40(11):  2593-2599 . 
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    Porcine epidermal growth factor (pEGF) can stimulate dormant primordial follicle into active follicle and stimulate growth of gastrointestinal (GI) tract and repair the GI tract in pigs, it may enhance productivity in sows and reduce the stress of early-weaned piglets, necessitating the development of recombinatant pEGF. 【Method】According to the codon usage preference of pichia pastoris, a pEGF gene was synthesized., a PCR was performed to obtain pEGF-6-His fragment using the synthetic pEGF gene as template. Then pEGF-6-His fragment was cloned into plasmid pPIC9. The resulting plasmid pPIC9-pEGF was linearized and transformed into pichia pastoris by electroporation, multicopy strains were screened out by dot blotting analysis, and the target protein in the medium supernatants was purified by His-tag affinity column. The purified protein was analyzed by Western bloting using anti His-tag monoclonal antibody, amino-terminal sequencing, and in vitro bioactivity assay. 【Results】The stronger hybridization signal of the transformant in dot bloting, the more obvious target protein band from this transformant was observed in Tricine-SDS-PAGE. An immunobloting band was observed in the western bloting analysis, and N-terminal amino-acid sequencing showed that purified products contained two peptides. The N-terminal sequence of one peptide was the same as the sequence of the nature pEGF; and the other peptide was Glu-Ala -pEGF. Finally, the expressed pEGF fusion protein could significantly increase the proliferation of BALB/c 3T3 cells. 【Conclusion】These results indicated that a recombinant strain which can effectively and stably produce recombinatant porcine epidermal growth factor with high biaoactivity was obtained.
    An In Vitro Digestion Device and Parameters for Broiler
    Scientia Agricultura Sinica. 2007, 40(11):  2600-2606 . 
    Abstract ( 1005 )   PDF (232KB) ( 468 )   Save
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    An in vitro digestion device, adopting continuous dialysis method, was devised to imitate the nutrients digestion and absorption in crop, gizzard and proventriculus and small intestine of broiler. The suitable parameters, such as buffer flow rate, dialysis tube molecular weight cutoff, feed sample particle size and weight were studied too. Crude protein (CP) and starch digestibility rise with buffer flow rate. When buffer flow rate is 2.0ml/min both CP and starch digestibility is higher than when buffer flow rate is 1.0 ml/min and 1.5 ml/min respectively (P<0.01), but lower than 2.5ml/min (P<0.05). CP and starch digestibility were improved by increasing dialysis tube molecular weight cutoff from 12000 to 14000 Da and decreasing feed sample particle size from 40 Mu to 60 Mu. Feed sample weight also has effects on CP and starch digestibility in vitro. When1.5g feed sample digested in vitro CP and starch digestibility was lower than 0.5g and 1g (P<0.01), but there is no significant difference between 0.5g and 1g. In conclusion, the suitable buffer flow rate, size of dialysis tube molecular weight cutoff, particle size and weight of feed sample of this in vitro digestion device for broiler were 2.0ml/min,12000~14000Da, 60mu and 1g respectively. The device shows a good stability and replication. Both of CP and starch digestibility coefficient of variation in vitro are below 5%.
    A study on the in vitro culture of buffalo preantral follicles
    Scientia Agricultura Sinica. 2007, 40(11):  2607-2614 . 
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    Growth of buffalo preantral follicles in vitro culture was studied to investigate the effects of size of preantral follicles, methods of culture, relative factors. In experiment 1, Effects of ascorbic acid (Vc), FSH and EGF on the in vitro development of buffalo preantral follicles were examined. Ascorbic acid can maintain the follicular morphologic integrity during culture but does not affect the survival and growth of follicles. FSH can promote the growth of follicles, but does not affect the survival and morphology of follicles. The growth promotive role of FSH is enhanced by the presence of Vc. EGF can accelerate the diameter increasing of follicles in the early culture stage, and this action is enhanced in the presence of FSH. In experiment 2,The in vitro growth of follicles in different diameters (60~180µm) was examined. As the follicular diameter increases, the survival rate and growing extent of follicles increases, the morphological abnormity of follicles decreases. In experiment 2, Conventional, two dimension (agarose coating) and three dimension (agarose embed) culture system were compared in their efficiency of supporting follicle growth. Three dimensions culture system is proved to be suitable for culturing the follicles in diameter of 60~100µm, while the two dimension culture system is proved to be suitable for culturing the follicles in diameter of 100~140µm.
    Fusion Expression of Duck Leptin Gene in Escherichia coli and Determination of Recombinant Protein Bioactivity
    Scientia Agricultura Sinica. 2007, 40(11):  2615-2620 . 
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    Abstract:【Objective】To investigate the expression characteristic of duck leptin in E.coli BL21 and the bioactivity of the expression product.【Method】Constructive the recombinant duck leptin gene prokaryotic expression strain. The recombinant strain was induced in different time and different concentrations of IPTG. After purification, renaturation and condensation, the product was injected into Kunming mice. The body weight, food intake and body weight of mice were analyzed.【Result】The fusion protein was specifically expressed. The results of SDS-PAGE analysis indicated that the molecular weight of the fusion protein was about 20kDa, which included the 16kDa protein expressed from duck leptin gene. The aimed protein was expressed with the induction of 0.2mmol/L IPTG, which was about 57% of total protein in bacteria. The recombinant protein reduced body weight、food intake and body weight on the testing in Kunming mice.【Conclusion】Duck leptin was high effective in E.coli BL21. The purified recombinant protein was proved to be biologically activity.
    Study on Antimicrobial resistance transfer in vitro and existent selectivity in vivo of avian antimicrobial-resistant Enterobacteriaccae
    Scientia Agricultura Sinica. 2007, 40(11):  2621-2625 . 
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    PCR amplification of bacterial gyrA and ParC genes indicated that amino acid codons of Ser-83 and Asp-87 were mutation from gyrA and parC genes were not mutation in fluoroquinolone-resistant strains. Conjugational transfer test was performed using donor resistant to tetracycline (TE), ampicillin (AMP), Sulfamethoxazole-trimethoprim ( SXT) and recipient sensitive to TE、AMP、SXT. Result showed that resistance of TE、AMP、SXT could transfer among Escherichia coli and frequency of TE conjugal transfer is 3×10-7. Mixed two groups chicken which inoculated multi-antimicrobial-resistant Escherichia coli (E.loli) and multi-antimicrobial-resistant salmonella (sal) respectively. The multi-antimicrobial-resistant E.coli and sal could be isolated from all chicken after inoculated 3days. But CIP-resistant strains decreased during the time run out and disappeared after inoculated 23days. The result indicated antimicrobial-resistant bacteria can diffuse quickly and unforced eliminated quickly from vivo of host if only the chicken without pressure of antibiotic.
    Comparative Analysis of Proteome Complement between Worker Bee Larvae of High Royal Jelly Producing Bees (A. m. ligustica) and Carniolians (A. m. carnica) Bees
    Scientia Agricultura Sinica. 2007, 40(11):  2632-2636 . 
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    【Objective】This study is to compare the protein composition of the high royal jelly producing bee (A. m. ligustica) with that of carniolians (A. m. carnica) during their worker larval developmental stage.【Method】The experiment was carried out by two-dimensional gel electrophoresis.【Result】 The results showed that significant higher number of total proteins (283) were detected in larvae of high royal jelly producing bees (Jelly bee) than those of carniolian bees (152) on 2-day old larvae. Among them 110 proteins were presented on both of the strains bees larvae, while 173 proteins were specific to larvae of Jelly bees, and 42 proteins were exclusive to carniolian larvae. While on the fourth day, a significant higher number of total proteins (290) were detected in larvae of Jelly bees than those of carniolian bees (240), 163 proteins resolved to both bees larvae, and 127 proteins were specific to Jelly bees and 77 proteins to carniolian bees. Until the sixth day, also a significant higher number of total proteins (236) were detected in larvae of Jelly bees than those of carniolian bees (180), 132 proteins were constantly expressed in two bees larvae, while 104 and 48 proteins are unique to Jelly bees and carniolian larvae, respecitively.【Conclusions】we tentatively concluded that the metabolic rate and gene expression of Jelly bees larvae is more higher than those of carniolian bees based proteins detected as total proteins and proteins specific to each stage of two strains of bee larvae. Proteins constantly expressed on 3 stages of larval development with some significant differences between two bees strains and, proteins unique to each stage expressed differences in term of quality and quantity, indicating that larval development need house keeping and specific proteins to regulate its growth at different development phage, but the expression mold is different between two strains of larval development.
    RESEARCH NOTES
    On the Before-Harvesting and After-Harvesting Seed Deterioration Resistance of 92 Spring Soybean Germplasm From South China
    Scientia Agricultura Sinica. 2007, 40(11):  2637-2647 . 
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    The seed deterioration of spring soybean in South China has been a great obstacle to the development of the spring soybean production in the region. The seed deterioration resistance germplasm needed to be used in the study of the resistance mechanism, and the development of the new cultivars. The main aim of the research was to evaluate the seed deterioration resistance of 92 spring soybean landraces and cultivars from South China by the methanol treatment and incubating weathering treatment, and to screen the seed deterioration resistance accessions. The results showed that no consistency between the resistant degrees of the before-harvesting and after-harvesting seed deterioration was found in 92 spring soybean germplasm of South China, and the former was generally great than the latter. The germplasm resisting the before-harvesting seed deterioration was more abundant in the spring soybean resource of South China. Significant positive correlations among the germinative percentage, germinative energy, vigor index and simple vigor index were found. The combination of the germinative percentage, vigor index and simple vigor index should be used as the evaluation index of the seed deterioration. 5 accessions resisting before-harvesting seed deterioration with the germinating percentage ≥80%, vigor index ≥1.00, and simple vigor index ≥8.61 were identified. 4 accessions resisting after-harvesting seed deterioration with the germinating percentage ≥80%, vigor index ≥2.64 and simple vigor index ≥7.03 were identified. One both resisting before-harvesting and after-harvesting seed deterioration, and one both unresisting before-harvesting and after-harvesting seed deterioration, were screening out.
    Construction of Site-specific Integration Vector of E2 gene of Hog Cholera Virus for Transformation of Chloroplast Genome of Lotus corniculatus
    Scientia Agricultura Sinica. 2007, 40(11):  2648-2654 . 
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    The objective of this research is to construct a site-specific integration vector harboring the E2 gene of Hog Cholera Virus, the gene coding for the main antigen, for transformation of chloroplast genome of Lotus corniculatus, which is the groundwork for producing edible plant vaccines in the chloroplast of this forage. The optimal site was selected for integration of exogenous genes into the chloroplast genome of Lotus corniculatus, and primers were designed and used to amplify chloroplast DNA fragments. After cloning of these fragments, the plastid transformation vector of Lotus corniculatus was constructed. The constructed vector, the pAKE2, contains two neighboring DNA fragments of 1.35 kb and 1.5 kb in the region of psbA and trnK genes, respectively, as targeting sequences for the chloroplast transformation of Lotus corniculatus, as well as the E2 gene cassette, which is inserted between the strong chloroplast promoter Prrn and the terminator of psbA gene form tobacco, and the aadA cassette, which is used for spectinomycine resistance selection of transformants. The results of PCR amplification and restriction enzyme digestion analysis showed that the constructed vector is in full accordance with what was desired. The transformation and following works are in progress.
    Virulence Detection of Streptococcus suis type 2 in Zebrafish
    Scientia Agricultura Sinica. 2007, 40(11):  2655-2658 . 
    Abstract ( 1096 )   PDF (260KB) ( 937 )   Save
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    Zebrafish (Danio rerio) is a new infection model for studying mammal pathogens. 1 005 80-day-old AB line inbred zebrafish were grouped and infected intraperitoneally with 8 highly virulent strains for pigs(mrp+ef+). The 50% lethal dose(LD50) were in the range of 5.36×103cfu to 5.01×104 cfu1 at 96 h. The SS2 strains which highly virulent for pigs also caused high morbidity and mortality in zebrafish. Acute septicemia were observed in inoculated fish. The bacteria inoculated could be reisolated from the organs of the fish. 1 strain avirulent for pigs(mrp - ef -)was also inoculated but not lethal for fish, and its LD50 was >106 cfu. There is significant difference between the LD50 of SS2 virulent strains and avirulent one(p<0.01). It concludes that zebrafish will be useful for further research of SS2 infection as an new animal model.