Scientia Agricultura Sinica

Growth Period and Yield of Early-Maturing Spring Maize in Northeast China from 2002-2009

WANG Yu-Ying, ZHANG Zheng-Bin, YANG Yin-Fu, WANG Min, ZHAO Jiu-Ran, YANG Guo-Hang

Scientia Agricultura Sinica. 2012, 45(24): 4959-4966. doi:10.3864/j.issn.0578-1752.2012.24.001

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【Objective】In the context of global climate change, the objective of this research is to analyze the phenophases and yield changes of early-maturing spring maize in Northeast China and provide scientific evidence for the variety cultivation and breeding direction of maize.【Method】The phenological phase data, yield traits and meteorological data from 2002 to 2009 at 10 stations in 4 provinces were analyzed. The possible effects of climate warming on spring maize production and breeding in Northeast China were analyzed.【Result】Growth period, vegetative period and anthesis kernel stage of check varieties showed a strong positive correlation with the active accumulated temperature. Along with the increase of active accumulated temperature, the growing period and anthesis kernel stage tended to be longer. There is a significant positive correlation between check varieties yield and annual average temperature (r=0.647*，Sig.=0.041，α=0.05). With the increase of the average temperature, the check varieties production presented an increasing trend. Meanwhile, spring maize cultivation methods have been changed, the optimum density was changed from low to high.【Conclusion】These results mean that climate warming has a significant positive impact on spring maize growth period, production, cultivation and breeding direction in the Northeast China. Therefore, breeding direction needs to be adjusted to fit the climate warming, intensive planting, longer growth period, pest and disease resistance, drought resistance, high quality and high yield should be the breeding objective of spring maize in the future in Northeast China.

Association Analysis of K+ Uptake Features and Salt Stress Responsive Signal Pathway SOS in Arabidopsis

CHEN Dan-Dan, CHEN Ming, XUE Fei-Yang, XU Zhao-Shi, LI Lian-Cheng, MA You-Zhi, MIN Dong-Hong

Scientia Agricultura Sinica. 2012, 45(24): 4967-4977. doi:10.3864/j.issn.0578-1752.2012.24.002

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【Objective】 To clarify the relationship between salt stress response and K+ uptake in plants, dynamic change of K+ uptake in SOS mutants under salt stress was investigated by using three Arabidopsis mutants of sos1, sos2, and sos3 involved in the SOS signal pathway as materials.【Method】 The Arabidopsis mutants materials plus the wild type (WT) were treated on MS medium containing various concentration ratios of Na+/K+, then their phenotypes in plant appearances were observed and analyzed by comparison. Also their roots scanning, RGR (relative growth rate), Na+, and K+ content, and Na+/K+ ratio in vivo were tested. Furthermore, the expression difference of K+ transporter genes such as AKT1, AKT2 and SKOR between the materials was identified by qRT-PCR. 【Result】No significant difference was found in the above explored traits between the mutants and WT when they were cultured on the MS medium with different concentrations of K+. In the treatment of 30 mmol•L-1 NaCl and the range of 0.2-60 mmol•L-1 K+, the increase of K+ concentration alleviated the growth inhibition of the mutants caused by high salt stress, and reduced the Na+/K+ ratio and enhanced the K+ concentration in vivo in all materials. Under a fixed treatment, Na+/K+ ratio was higher in the mutants than in WT, but K+ concentration was higher in WT than in the mutants. However, when K+ up to 80 mmol•L-1 in medium the growth of the mutants was inhibited again, and at the same time Na+/K+ ratio increased and K+ decreased in vivo of all plants. Real-time PCR analysis showed that the expression of AKT1 and SKOR was relatively low under the condition of 30 mmol•L-1 NaCl and low concentration potassium (0.2 mmol•L-1 K+). Under 30 mmol•L-1 NaCl and high concentration potassium (20.05 mmol•L-1 K+ or 60 mmol•L-1 K+), the expressions of AKT1, AKT2 and SKOR appeared no significant difference and their expression patterns were almost similar in different mutants. 【Conclusion】 Under moderate salt stress conditions, growth suppression of the plants caused by the salt stress could be alleviated with the increase of K+ concentration. But, when the concentration of external univalence cation was over 110 mmol•L-1, the growth status of the plants was restrained again. Therefore, it was speculated that SOS signaling pathway was not involved in the regulation of absorption and transport of K+ directly.

Effects of Chilling Stress on Protein and Related Gene Expression in Chloroplasts of Sugarcane

HUANG Qiao-Ling, HUANG Xing, SUN Fu, SUN Bo, YANG Li-Tao, LI Yang-Rui

Scientia Agricultura Sinica. 2012, 45(24): 4978-4987. doi:10.3864/j.issn.0578-1752.2012.24.003

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【Objective】 The present study was conducted to investigate the effects of chilling stress on chloroplasts at protein and mRNA levels to provide references for further investigation on molecular mechanism of chilling stress in sugarcane.【Method】Sugarcane varieties GT28 (strong cold resistant sugarcane variety) and ROC22 (weak cold resistant sugarcane variety) were employed as the plant materials, and treated for 9 d, 15 d and 24 d of chilling stress, respectively, and then the chloroplast protein was extracted and used for electrophoresis analysis, and expressions of the genes were analyzed using real-time PCR.【Result】The results of electrophoresis analysis showed that, for both sugarcane varieties, the relative content of chloroplast protein decreased with the chilling time extension. The protein bands of 39.92, 32.95 and 22.87 kD were down-regulated obviously. Mass spectrometry revealed that they were ATP synthase subunit gamma, oxygen-evolving enhancer protein 1 and chloroplast 23 kD polypeptide of photosystem II, and they were encoded by atpC, psbO and psbP genes, respectively. Their fragment length was 937, 996, and 721 bp, respectively. The obtained fragment of psbO gene was its complete open reading frame, which has been registered in the GenBank with the accession number JQ898540. Real-time PCR analysis showed that chilling stress suppressed the expression of atpC gene, but induced the expressions of psbO and psbP genes, which reached the maximum at the time point of 15 d. 【Conclusion】 Generally, chilling stress promoted protein degradation, and the protein declined more in ROC22 than that in GT28. Chilling stress suppressed the expression of atpC gene, but induced the expressions of psbO and psbP genes in chloroplasts of sugarcane.

Changes of Cell Ultrastructure of Flue-Cured Tobacco Leaves with Different Maturities During Bulk Flue-Curing

LIU Chao-Ying, XU Zi-Cheng, SHAO Hui-Fang, SONG Chao-Peng, YANG Jie, GENG Zong-Ze, ZHAO Shuang, ZHANG Li-Ying

Scientia Agricultura Sinica. 2012, 45(24): 4988-4997. doi:10.3864/j.issn.0578-1752.2012.24.004

Abstract ( 511 )

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【Objective】The flue-cured tobacco cv. Honghuadajinyuan (hereafter referred as “HD”) was taken as experimental material to study the changes of cell ultrastructure of tobacco leaves during bulk-curing, which intended to provide a theoretical basis for harvesting maturity and optimization of curing technique of HD. 【Method】Tobacco leaves of different maturities were cured in the bulk flue-curing room, the cell ultrastructures of which were studied respectively at key temperature points (38℃, 42℃, 48℃) during the flue-curing process. 【Result】 Results of cell ultrastructure observation showed that the differences of cell structures of fresh tobacco leaves among various maturity degrees were mainly showed by the extent of chloroplast adhering to cell wall and the size of intercellular space. Chloroplast, nucleus and related membrane structure changed most obviously during the flue-curing process. Moreover, the yellowing process was the key stage for degradation of starch and pigmentary substances in tobacco leaves. Compared with the mature and over-ripe tobacco leaves, those harvested when optimally matured was beneficial to the transformation of carbohydrates and further degradation of starch and pigmentary substances, by which the quality traits of tobacco leaves could also be improved at the same time.【Conclusion】Harvesting at an optimum maturity was quite essential for the improvement of leaf structure and quality.

Identification of the Characteristics for Forma Specials of Fusarium oxysporum Schl. Based on the Analysis of Fatty Acid Biomarkers

LIU Bo, HU Gui-Ping, XIAO Rong-Feng

Scientia Agricultura Sinica. 2012, 45(24): 4998-5012. doi:10.3864/j.issn.0578-1752.2012.24.005

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【Objective】 The objective of this study is to analyze the characteristics of PLFA biomarkers in Fusarium oxysporum Schl. by means of microbe identification system (MIDI system from USA). 【Method】 Twenty-two strains of F. oxysporum isolated from different hosts, e.g. watermelon, banana and peanut, were detected by MIDI system, the homogeneity of fatty acid from the fungi was analysed by clustering, and the key fatty acids of F. oxysporum were acquired by the method of PCA. The discriminant model for the forma specials of F. oxysporum was figured out by stepwise discriminant analysis.【Result】Eight fatty acids were identified in 22 strains of the forma specials, and there were 3 types of fatty acids such as 16:0, 18:0 and 18:2 CIS 9,12/18:0a related to existance in all strains. Using the cluster analysis method the 22 strains were classified into 4 groups based on the phospholipid fatty acids (PLFAs) biomarkers, which had association with origin, biochemical variant and pathotype of F. oxysporum. The 5 key fatty acids obtained 14:0 (X1), 16:0 (X2), 16:1 CIS 9 (W7) (X3), 18:0 (X4) and 18:2 CIS 9,12/18:0a (X5) were acquired by Principal Component Analysis (PCA). Bayes discrimination method was used to establish discriminant models. Four fatty acids of 14:0 (X1), 16:0 (X2), 18:0 (X4), 18:2 CIS 9,12/18:0a (X5) were put into the model set as follow: Y1=-183.06+12.24X1+8.05X2+5.39X4+ 3.58X5, Y2=-174.09+10.40X1+7.96X2+5.40X4+3.42X5, Y3=-173.97+14.85X1+7.25X2+ 6.58X4+ 3.53X5. The accurate rate for discrimination was up to 92.86%.【Conclusion】Fatty acids, e.g. 14:0, 16:0, 18:0, 18:2 CIS 9,12/18:0a, are the key factors in discriminating the host of F. oxysporum. The discriminant model is accord with the practice and should be well applied into use.

Identification and Evaluation of Resistance to Stripe Rust in 1980 Wheat Landraces and Abroad Germplasm

HAN De-Jun, ZHANG Pei-Yu, WANG Qi-Lin, ZENG Qing-Dong, WU Jian-Hui, ZHOU Xin-Li, WANG Xiao-Jie, HUANG Li-Li, KANG Zhen-Sheng

Scientia Agricultura Sinica. 2012, 45(24): 5013-5023. doi:10.3864/j.issn.0578-1752.2012.24.006

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【Objective】The objective of this study is to search new resistance sources and build evaluation system, and to provide a theological basis for breeding for disease resistance stripe rust of wheat. 【Method】 A total of 1 980 wheat landraces and foreign germplasms, which had not been widely used in China, were evaluated for resistance to stripe rust at seedling stage in greenhouse with 4 races of Puccinia triticina, and on adult plants under field conditions in Yangling and Tianshui, respectively, during 2008-2011. The selected resistant sources were detected with the known DNA markers linked to rust resistance genes Yr5, Yr9, Yr10, Yr15, Yr18 and Yr26.【Result】A selection of 50 resistant entries were screened in both artificial nursery with mixed races at Yangling and natural nursery at Tianshui, including 8 entries which had seedling resistance and 42 entries which had adult plant resistance. Combined with the resistance spectra and the detection of Yr gene markers, 6 entries possibly carried Yr9, 2 entries possibly carried Yr10, 21 entries possibly carried Yr18 in the resistant 50 entries. There was no indication of Yr5, Yr15 and Yr26 in any selected resistant entries. Six materials including Pindong34 and Qingchun39 displayed high or very high levels of resistance, which might carry uncharacterised and full compatibility at the seedling stage the new rust resistance Yr.【Conclusion】An effective method was established for identification and evolution of resistance to stripe rust, and 50 wheat germplasms were searched out with polygenic resistant characters. These resistant sources can be used in wheat breeding program for resistance to the disease.

Labeling Bacillus pumillus with Green Fluorescent Protein (GFP) and Its Colonization in Rice Seedlings

SHEN Xin-Qian, LIU Tong, HU Xiao-Lu, GU Zhen-Fang, CHEN Yun-Peng

Scientia Agricultura Sinica. 2012, 45(24): 5024-5031. doi:10.3864/j.issn.0578-1752.2012.24.007

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【Objective】 The objective of this study is to investigate bacterial colonization in rice seedlings by GFP-labeled Bacillus pumilus DX01 and lay a solid foundation for the application of phytopathogenic biocontrol. 【Method】 Genetically stable mutants of B. pumilus DX01 with a strong GFP expression were identified from the GFP-labeled Tn5 insertion library and used for tracing the bacterial colonization in rice seedlings. 【Result】 A total of 1 467 mutants were subjected to qualitative and quantitative analyses of GFP expression by using fluorescence microplate reader, fluorescence activating cell sorter and fluorescent microscopy, and eventually 8 mutants with significantly enhanced GFP expression were identified. Meanwhile, the copy numbers of exogenous DNA integration in the genome of these mutants were detected. The GFP-tagged bacterial cells that released into the rhizosphere of rice seedlings could survive for more than 15 days. Furthermore, decrease of the B. pumilus bacterial cells in undisinfected soils showed more slowly compared with corresponding sterile soils. 【Conclusion】 B. pumilus mainly locates in root hair region and later root branch. Meanwhile, the bacterial film formed on rice root surface was also confirmed. B. pumilus can invade plant through the wound of roots or by young root hairs, and they distribute mostly in root cortex cells and intercellular spaces of cortical layer. The marked bacteria were often found in the vascular bundle of rice seedlings. In conclusion, B. pumilus displayed a good colonization ability in the rhizosphere soils of rice seedlings.

Effects of Anti-Fungal Transgenic Rice on the Target Fungal Diseases and the Non-Target Bacterial Diseases and Insect Pests in Paddy Fields

LI Wei, GUO Jian-Fu, YUAN Hong-Xu, LI Yue-Ren, LIU Yue-Lian, HUANG Yong-Xiang, JIANG Shi-He

Scientia Agricultura Sinica. 2012, 45(24): 5032-5039.

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【Objective】The study aimed at the effects of transgenic rice with four anti-fungal genes on the target fungal diseases and the non-target bacterial diseases and insect pests in paddy fields. 【Method】 Two transgenic rice lines, E122-1 and E127-1, which were overexpression of rice acidic chitinase gene (RAC22) and rice basic chitinase gene (RCH10) and transformed with alfalfa β-1,3- glucanase gene (β-Glu) and barley ribosome inactivating protein gene (B-RIP), were tested for their effects on the target fungal diseases (rice blast, rice false smut and rice brown spot) and the non-target bacterial diseases (rice bacterial blight and rice bacterial leaf streak and insect pests (rice yellow stem borer and rice leaf roller) by means of innoculation in greenhouse and investigation in paddy fields, compared with their untransformed counterpart E32. 【Result】Both E122-1 and E127-1 showed broad spectrum of resistance against rice blast isolates and were significantly lower in the percentages of infected plants and the disease index resulted from rice false smut or rice brown spot, but had no significant difference in the percentages of susceptible plants and the disease index resulted from rice bacterial blight or rice bacterial leaf streak, the percentages of “dead heart” plants resulted from rice yellow stem borer and the percentages of leaf-rolled plants resulted from rice leaf roller in comparison with the counterpart E32. On the plants with resistance to rice bacterial blight, both E122-1 and E127-1 had significant higher number plants with no infected symptom and had significant lower number plants with the 3rd scale infected symptom than that of the counterpart E32. 【Conclusion】 Both E122-1 and E127-1 exhibited a high resistance to rice blast, rice false smut and rice brown spot, and did not cause obvious population increase of rice bacterial blight, rice bacterial leaf streak, rice yellow stem borer and rice leaf roller as compared to their counterpart during growing period in paddy fields.

Diagnosis of the Damage of Cnaphalocrocis medinalis at the Booting Stage of Rice Using Spectral Reflectance

SUN Qi-Hua, LIU Xiang-Dong

Scientia Agricultura Sinica. 2012, 45(24): 5040-5048. doi:10.3864/j.issn.0578-1752.2012.24.009

Abstract ( 658 )

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【Objective】 The objective of this study is to research the spectral characteristics from canopy, undamaged and damaged leaves of rice at the booting stage, and to build the regression models based on the spectral parameters to diagnose the damage levels of rice leaf folder (RLF) (Cnaphalocrocis medinalis). 【Method】 The reflectance from rice canopy, undamaged leaves and damaged leaves by RLF was measured by Hand-held Spectroradiometers, and correlation analysis was made to explore the sensitive wavebands of spectra to damage levels. The linear and stepwise regression methods were introduced to construct the diagnostic models of damage levels of rice based on the spectral parameters.【Result】Reflectance from rice canopy at the near infrared regions decreased significantly with the increase of damage levels of rice, and the 738-1 000 nm was the sensitive wavebands to exhibit the damage of RLF. The reflectance from the undamaged leaves collected from the damaged plot also had the capability to exhibit the damage levels of RLF, and there was a significantly negative correlation between the reflectance at 512-606 or 699-1 000 nm and the damage levels. However, the reflectance at 582-688 nm from the damaged leaves had a significantly positive correlation with the damage levels. Consequent change in amplitude and area of red-edge from canopy, undamaged and damaged leaves occurred significantly when the rice was damaged by RLF, and the regression models to diagnose the damage levels using the spectral parameters were built. The diagnosing error of the model based on the red-edge amplitude from rice canopy or based on the reflectance at 550 nm from the undamaged rice leaves was lower, and the stepwise regression model’s based on all the 21 spectral indices from canopy, undamaged and damaged leaves was the lowest. These models could be used to monitor the damage by RLF.【Conclusion】The reflectance at 738-1 000 nm from the canopy and at 512-606 and 699-1 000 nm from the undamaged leaves of rice could reflect well the damage levels of rice by RLF, and the spectral models based on reflectance and red-edge parameters from the canopy and undamaged leaves could be used to diagnose the damage of RLF.

Study on N Fertilizer Efficiency and the Residual Effect Under Rice-Oilseed Rape Rotation System

BU Rong-Yan, REN Tao, LU Jian-Wei, LI Xiao-Kun, LI Yun-Chun, WANG Yang, LU Jun-Ming

Scientia Agricultura Sinica. 2012, 45(24): 5049-5056. doi:10.3864/j.issn.0578-1752.2012.24.010

Abstract ( 689 )

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【Objective】 To optimize fertilization strategy further in the rice-oilseed rape rotation system, the effects of N fertilizer application on crop yield, N uptake, N use efficiency and the residual effects of N fertilizer applied in rice season were studied in the annual rotation system. Meanwhile, the economical benefit with different N fertilizer treatments in the rice-oilseed rape rotation system were estimated. 【Method】A field experiment, to study crop yield, N uptake, N use efficiency, the residual effects of N fertilizer and economical benefit in the rice-oilseed rape rotation system were conducted in Honghu county, Hubei province from May 2010 to May 2011. Different N application rate treatments was included in the rice season. While in the oilseed rape season the original treatment in the rice season was split into with and without N application sub-treatments. 【Result】 Due to the different application rate and allocations of N fertilizer, the differences among the yield, N use efficiency and economical benefit were significant. In rice season, the yield and N use efficiency were the highest when N application rate was 165 kg N•hm-2. The residual effects of N fertilizer applied in rice season were significant, which could improve the yield of oilseed rape, ranging from 107 to 644 kg•hm-2. The N uptake of oilseed rape also increased significantly, from 3.9 to 35.2 kg N•hm-2. The residual effects of N fertilizer were equivalent to 5-33 kg N•hm-2 N fertilizer applied in the oilseed rape season. The residual effects were positively correlated with N application rate. Nevertheless, in the rice season excessive N fertilizer application rate would decrease the rice yield, N use efficiency and economical benefit. Overall the economical benefit was the largest when both N application rate in rice and oilseed rape season were 165 kg•hm-2. 【Conclusion】Reasonable N fertilization could significantly increase yield of rice and oilseed rape. N application in rice season had a significant residual effect. Therefore, optimum N fertilization management in oilseed rape season should consider the residual effect of N application in rice season.

Retention and Desorption of Exogenous Chlortetracycline(CTC) on Corn-Straw Derived Biochar

GUAN Lian-Zhu, ZHAO Ya-Ping, ZHANG Guang-Cai, ZHANG Yun, YAN Li

Scientia Agricultura Sinica. 2012, 45(24): 5057-5064. doi:10.3864/j.issn.0578-1752.2012.24.011

Abstract ( 490 )

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【Objective】 In order to reduce chlortetracycline (CTC) pollution from waste water and animal dung, the retention and desorption characteristics of exogenous CTC onto the corn-straw derived biochar were studied. 【Method】The OECD Guideline106 batch equilibrium method was used to study the adsorption kinetics and adsorption-desorption thermodynamic characteristics of CTC onto the corn-straw derived biochar. 【Result】 The results showed that the retention kinetics of CTC onto the tested biochar included two stages of rapid response and slow balance. Twelve hours was taken to reach the retention equilibrium. The retention behavior of CTC onto the tested biochar fitted second-order kinetics model (average R2 is 0.9999) well. The retention isotherm at different temperatures fitted Freundlich model (average R2 is 0.9174) well. The adsorption capacity (lgKf = 3.6575-3.7377) and the adsorption intensity (1 / n = 0.8647-1.0478) were both high and became higher as temperature increasing. The shape of adsorption isotherm gradually changed from L-shaped to linear as temperature increasing; the retention of CTC onto the tested biochar was a spontaneous endothermic process and the main mechanism was physical retention. The desorption rate of CTC on the tested biochar varied from 2.57% to 6.99% and decreased with the temperature increasing, which meant the retention of CTC on the corn-straw derived biochar was more firm when increase the temperature.【Conclusion】As the tested corn-straw derived biochar can strongly absorb the CTC and the desorption rate was relative low, so that the tested corn-straw derived biochar has a good removal efficiency of exogenous CTC in aqueous phase.

Effect of Nano-Packing Material on Improvement of Preservation Quality of Agaricus bisporus

YANG Wen-Jian, DAN Nan, YANG Qin, FANG Yong, ZHAO Li-Yan, AN Xin-Xin, MA Ning, LIU Yin-Hong, XIN Zhi-Hong, HU Qiu-Hui

Scientia Agricultura Sinica. 2012, 45(24): 5065-5072. doi:10.3864/j.issn.0578-1752.2012.24.012

Abstract ( 669 )

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【Objective】A polyethylene (PE) packing material containing nano-Ag, nano-TiO2, and attapulgite was prepared and applied in the preservation of Agaricus bisporus, and its effects on sensory quality and physiological and nutritional properties of Agaricus bisporus were analyzed and determined during the 10 days storage at 4 ℃. 【Method】The effect of nano-packing material on sensory quality, physiological indexes and main nutritional value of Agaricus bisporus was studied by tracking the changes of weight loss, whiteness, relative conductivity, polyphenoloxidase activity, and MDA, total sugar and soluble protein contents. The normal PE material was used as control. 【Result】Compared with the control, water loss and browning of Agaricus bisporus were inhibited by nano-packing material. The weight loss, relative conductivity, MDA content, and polyphenoloxidase activity of Agaricus bisporus treated by nano-packing material were 1.46%, 22.5%, 3.50 µmol•kg-1, and 161.89 U•g-1•min-1, respectively, which were significantly lower than that of control (1.86%, 30.2%, 4.66 µmol•kg-1, and 233.84 U•g-1•min-1) (P＜0.05). Retention rate of total sugar and soluble protein of Agaricus bisporus treated by nano-packing were significantly higher compared with control. 【Conclusion】Nano-packing material had a potential on inhibiting the sensory quality degenerating and nutrition loss of Agaricus bisporus, as well as improving the preservation quality and extending preservation time.

The Principle of Food Geographical Origin Traceability and Authenticity Technique

WEI Yi-Min, GUO Bo-Li, WEI Shuai, SUN Shu-Min, ZHAO Hai-Yan

Scientia Agricultura Sinica. 2012, 45(24): 5073-5081. doi:10.3864/j.issn.0578-1752.2012.24.013

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The food geographical origin traceability and authenticity is very important for food safety surveillance, and it is also important for protecting sustainable development of geographical or special food. The aim of the study is to explore the principle and method of food geographical origin traceability and authenticity, and to promote the research and application of food traceability and authenticity technology. The basic thought, step and method of food geographical origin traceability and authenticity were summarized by analyzing principle and application. The basic thought of food geographical origin traceability and authenticity technology is analyzing the difference in characteristics of geographical origin, building the discriminant mode, testing the discriminant mode, building the database, and discriminant and testing analysis. The basic method is the chemometrics which synthesizing the chemical composition analysis and Multivariate statistics such as analysis of variance, multiple comparison analysis, cluster analysis, principal component analysis, discriminant analysis and so on. The food geographical origin traceability and authenticity is a technology system for distinguishing the food geographical origin based on chemical composition analysis and multivariate statistics.

Energy Requirement Parameters of 20-35 kg Dorper and Thin-Tailed Han Sheep Crossbred Male Lambs

XU Gui-Shan, DIAO Qi-Yu, JI Shou-Kun, DENG Kai-Dong, JIANG Cheng-Gang, TU Yan, LIU Jie, ZHAO Yi-Guang, MA Tao, LOU Can

Scientia Agricultura Sinica. 2012, 45(24): 5082-5090. doi:10.3864/j.issn.0578-1752.2012.24.014

Abstract ( 506 )

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【Objective】 The research aimed to define the energy requirement for maintenance and growth of metabolic energy and net energy for 20-35 kg Dorper and Thin-Tailed Han crossbred F1 ram lambs, to provide a theoretical basis of scientific feeding mutton ram lambs. 【Method】 The trial was conducted according to a completely random design and lasted for 66 days. Fifty Dorper and Thin-Tailed Han ram lambs crossbred F1 lambs were selected, thirty five lambs were used for slaughter trail and 15 lambs were used for digestibility trial. Seven lambs were randomly chosen and slaughtered at (20.26±1.29) kg BW for measuring the initial body composition. The remaining 28 ram lambs were offered a pelleted mixture diet for ad libitum intake, or 70 or 40% of the ad libitum intake. Seven of the ram lambs were randomly chosen and slaughtered when the 14 ram lambs fed ad libitum reached (28.54±2.29) kg. The remaining 21 ram lambs were randomly divided into 3 intake levels and fed a pelleted mixture diet, and the lambs were all slaughtered when the lambs in ad libitum treatment group reached at 35 kg of BW. In a digestibility trial, fifteen lambs (32.38±2.23) kg were randomly divided into three groups (five lambs in each group), the feed and the intake level were the same as slaughter experiment. Total collection of feces and urine was conducted. Methane production, carbon dioxide output and oxygen consumption were measured by open-circuit respirometry. 【Result】 The results showed that the maintenance requirements for NE and ME were 250.61 and 374.21 kJ•kg-1 metabolic shrunk BW (SBW0.75), respectively, with a partial efficiency of energy utilization for maintenance being 0.67. Net energy and metabolic energy requirements for growth ranged from 1.12 to 5.31 MJ•d-1 and 2.63 to 12.03 MJ•d-1, respectively, for the lambs gaining 100 to 350 g•d-1 from 20 to 35 kg body weight. The partial efficiency of ME for growth was 0.419. 【Conclusion】 Maintenance requirement for net energy and metabolic energy, net requirements and metabolic energy for gain of 20-35 kg Dorper and Thin-Tailed Han ram lambs crossbred F1 lambs were determined. These parameters were slightly lower than those reported by NRC and AFRC.

Cloning, Sequence Analysis and Over-Expression of SCD Gene of Dairy Goat

SHI Heng-Bo, LUO Jun, ZHU Yue, WANG Zi-Qian, ZHAO Wang-Sheng

Scientia Agricultura Sinica. 2012, 45(24): 5091-5101. doi:10.3864/j.issn.0578-1752.2012.24.015

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【Objective】To study the function of stearoyl-CoA desaturase (SCD) gene in mammary gland fatty acid metabolism emphasizing on how it regulates genes involved in unsaturated fatty acid synthesis as well as its impact on fatty acid composition.【Method】The sequence of SCD in dairy goat was cloned using RT-PCR for bioinformatics and tissue mRNA expression analysis. A recombinant adenovirus vector was constructed to over-express the gene in cultured goat mammary epithelial cells. Changes of gene expression, protein yield and fatty acid contents after over-expression were detected with real-time fluorescence quantitative PCR, western blotting and GC-MS. 【Result】The CDS of goat SCD gene is 1080 bp in length, coding 359 amino acid residues (GenBank accession: GU947654). The SCD gene was expressed higher in mammary gland, lung and subcutaneous fat, lower in heart, rumen and ovary. Recombinant adenovirus vector containing goat SCD open reading frame was constructed, packaged and amplified in HEK293. The gene expressions of FASN, A-FABP, LEPR and LXRα were down regulated after over-expression of SCD, while expressions of PPARγ and LPL were up regulated significantly. Synthesis of palmitic acid and stearic acid in the cells decreased, while unsaturated fatty acids increased.【Conclusion】 SCD gene plays an important role in goat mammary fatty acid metabolism, and a major role in unsaturated fatty acid synthesis by interaction with other genes including FASN, H-FABP, LEPR, LXRα, PPARγ and LPL.

Investigation on Contamination Situation of Aflatoxin in Detected Feeds and Feedstuffs in Beijing Area

FAN Yu, LI Xiao-Ying, ZHAO Li-Hong, JIA Ya-Xiong, JI Cheng, MA Qiu-Gang, CHEN Yu, WANG Liang

Scientia Agricultura Sinica. 2012, 45(24): 5102-5109. doi:10.3864/j.issn.0578-1752.2012.24.016

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【Objective】This study was conducted to analyze and evaluate the contamination situation of aflatoxin in feeds and feedstuffs in Beijing area. 【Method】 A total of 187 feed samples from 21 farms in Beijing were sampled to detect and quantify the content of aflatoxin (B1, B2, G1 and G2). An efficient HPLC with post-column photochemical derivatization method was developed, including immunoaffinity step for aflatoxin extraction from feeds and feedstuffs followed by liquid chromatography (LC) for quantification. 【Result】 Results showed that the detection rate of AFB1 in corn, bran, soybean meal, DDGS, swine and poultry complete feeds was 50.0%, 46.2%, 33.3%, 94.1%, 67.1% and 94.3%, the over standard rate was 6.2%, 0.0%, 0.0%, 5.9%, 6.6% and 0.0%, and the average content was 5.98, 0.25, 1.00, 9.83, 2.89 and 1.06 µg•kg-1, respectively. 【Conclusion】 These results indicated that the average content of aflatoxin in complete feeds, corn and DDGS were the highest. Aflatoxin contamination was widely found in both feeds and feedstuffs.

The Regulation of Autoinducer-2 in Avian Pathogenic Escherichia coli

BAI Hao, HAN Xian-Gan, LIU Lei, DAN Xue-Qin, SONG Jun, LIU Rui, DONG Hong-Liang, LIU Hai-Wen, DING Chan, YU Sheng-Qing

Scientia Agricultura Sinica. 2012, 45(24): 5110-5116. doi:10.3864/j.issn.0578-1752.2012.24.017

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【Objective】 The aim of the study was to investigate the modulation of AI-2 on the biofilm forming ability and virulence in Avian Pathogenic Escherichia coli (APEC). 【Method】 The improved crystal violet seme-quantitative method and fluorescence staining method were used to study the effects of AI-2 on the biofilm forming ability in APEC. The effects of AI-2 on the mRNA levels of the virulence genes were analyzed using real-time PCR. Viable bacteria counting method was used to evaluate the effects of AI-2 on the capability of APEC to adhere and invade DF-1cell. 【Result】The results showed that the biofilm forming ability decreased at the concentration of 0.185 mmol•L-1 AI-2,while the biofilm forming ability had no significant change at the concentration of 0.037mmol•L-1 and 0.278 mmol•L-1 AI-2. Real-time PCR showed that Al-2 decreased the transcription of pfs, vat, lux, tsh, fuyA, iucD genes, while increased the transcription of ompA and iss genes. The adherence and invasion was decreased to 57.35% and 36.64% by supplementation with AI-2 in APEC. 【Conclusion】The biofilm forming ability increased at an optimal concentration of AI-2. The transcription of the virulence genes, the adherence and invasion to DF-1 cells of the bacteria were decreased by supplementation with AI-2 in the medium to culture the APEC. These findings will be of benefit to future studies of the role of AI-2 in APEC.

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