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Table of Content

    01 March 2019, Volume 52 Issue 5
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Cloning and Functional Analysis of a Root Development Related Gene OsKSR7 in Rice (Oryza sativa L.)
    ZHOU JiaQin,ZHU JunZhao,YANG SiXue,ZHU ZhouJie,YAO Jie,ZHENG WenJuan,ZHU ShiHua,DING WoNa
    Scientia Agricultura Sinica. 2019, 52(5):  777-785.  doi:10.3864/j.issn.0578-1752.2019.05.001
    Abstract ( 702 )   HTML ( 68 )   PDF (3071KB) ( 515 )   Save
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    【Objective】The root system of rice is an important agronomic trait closely related to shoot growth and yield. Identifying new root development-related genes in rice will help further clarification of the underlying molecular mechanisms.【Method】In the present study, a mutant with significantly shorter roots was isolated from an EMS (ethyl methane sulfonate)-generated mutant library of rice and designated as Osksr7 (Oryza sativa kasalath short root 7 ). By using solution culture and field planting, analysis of young seedling phenotype and main agronomic traits of mature plants was conducted. The F2 populations from crossing of Osksr7 with indica Kasalath and japonica Nipponbare were used for genetic analysis and map-based cloning, respectively. Candidate genes were examined by DNA sequencing. Complementation analysis of the Osksr7 mutant with the protein-coding region of OsKSR7 driven by the 35S promoter was performed using Agrobacterium tumefaciens -mediated transformation. 【Result】 At the seedling stage, the elongation of primary roots, adventitious roots, lateral roots and root hairs in Osksr7 was severely impaired. The length of primary roots, adventitious roots and lateral roots of Osksr7 was only 33%, 38.9% and 35.3% of those of the wild type, respectively. Nevertheless, the number of adventitious roots of Osksr7 was significantly increased when compared with the wild type. At the maturation stage, the agronomic traits of Osksr7 were also significantly compromized, including the shoot height, panicle number, clum thickness, seed setting rate, 1000-grain weight and length and width of flag leaves. Among them, the panicle number and seed setting rate of Osksr7 dramatically decreased to only 56.3% and 37.3% of those of the wild type, respectively. Genetic analysis showed that the growth of F1 plants from the crossing of Osksr7 with indica Kasalath was similar to the wild type and the segregation ratio of wild type and mutant phenotype plants in the corresponding F2 population fitted a ratio of 3:1, indicating that the mutant trait of Osksr7 was controlled by a single recessive nuclear gene. The OsKSR7 locus was further mapped between InDel markers IND1 and IND2 on chromosome 11 with a physical distance of 143 kb, where there were 25 predicted genes with annotation. Sequencing analysis found a point mutation (T 73 to A) in the first exon of the gene LOC_Os11g24560 within this region in Osksr7 , resulting in an amino acid substitution (Trp 25 to Arg). The gene encodes a putative rice homolog of the SEC23 subunit of the coat protein complex II (COPII) involved in ER-to-Golgi transport. RT-PCR analysis revealed no significant difference in the expression level of LOC_Os11g24560 between the wild type and Osksr7 . Transformation of Osksr7 with the coding sequence of LOC_Os11g24560 driven by the 35S promoter could successfully restore its growth defects, confirming that the mutation in LOC_Os11g24560 was responsible for the mutant phenotype of Osksr7 .【Conclusion】 Osksr7 is a rice short root mutant, and yield-related agronomic traits are significantly suppressed in Osksr7 . OsKSR7 is confirmed to be within the locus LOC_Os11g24560 , which encodes the SEC23 subunit of the coat protein complex II (COPII). OsKSR7 is not allelic to any previously reported rice root gene and is a newly identified regulator of root development in rice.

    Enrichment Profile of GA4 is an Important Regulatory Factor Triggering Rice Dwarf
    HUANG ShengCai,WANG Bing,XIE GuoQiang,LIU ZhongLai,ZHANG MeiJuan,ZHANG ShuQing,CHENG XianGuo
    Scientia Agricultura Sinica. 2019, 52(5):  786-800.  doi:10.3864/j.issn.0578-1752.2019.05.002
    Abstract ( 750 )   HTML ( 33 )   PDF (2445KB) ( 310 )   Save
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    【Objective】A dwarf rice mutant was generated by culturing rice embryo tissues and characterized to elucidate the reasons for leading to an occurence of semi-dwarf rice with more tiller number. It is expected that this study will provide a theoretical basis for scientifically cultivating rice varieties of lodging-resistant and high-yielding in overcoming the dwarf obstacle factors.【Method】In this study, both the rice dwarf mutant and wild type were phenotypically profiled, and the structural characteristics of flower and cell appearance of leaves were investigated by stereomicroscope and light microscopy; The differential gene expression profiles were analyzed by both the transcriptomics and qRT-PCR, and the sensitivity of the mutant to exogenous gibberellin was detected by spraying exogenous GA3; The enrichment profiles of gibberellin in the mutant were detected by a high performance liquid chromatography and a mass spectrometry. 【Result】Data showed that the mutant demonstrated a decrease of 56.59% in the average plant height and an increase of 47.44% in the effective tiller number compared with the wild type, respectively (P <0.01). Observation showed that the mutant led to disappearance of the epidermis and revealed a smaller stamen accompanying a delayed development in the flower organs. Although the mutant has a higher effective tiller number, but significantly lowers the seed setting rate, which only accounts for 12.62% of that in the wild type. The length and the width of grains also are significantly reduced (P <0.01). Stem longitudinal sections reveal that the mutant decreased the cell length of 23% compared with the wild type (P <0.01). However, when the mutant was exposed to exogenous gibberellin, the plant height, effective tiller number, seed setting rate, seed size, epidermis and the stem cell length were obviously restored, indicating that the dwarf mutant possibly results from the shortage of GA’s synthesis in plant. Transcriptome sequencing showed that the mutant significantly up-regulated the OsGA13ox gene, and exhibited an identical result with the qRT-PCR analyses. Since the OsGA13ox controls the conversion of the GA12 to the GA53, both of which are converted to the GA4 and the GA1, respectively. Particularly, the GA4 exhibits a higher activity than the GA1, suggesting that rice dwarf might be triggered by the reduction of GA4 enrichment in plant. Measurement confirmed that the accumulation of the GA4 in the mutant was decreased by 94.9% compared with the wild type. Additionally, as a specific receptor for SL (Strigolactone), the D14 gene is involved in the SL signaling transduction in plant, and thus inhibits branching or tillering. The qRT-PCR showed that the mutant significantly down-regulated the D14 gene compared to the wild type, however, both the wild type and the mutant significantly up-regulated after spraying GA3. The data suggested that the up-regulation of the D14 gene might lower the effective tiller number, while the down-regulation of the D14 gene possibly increase the effective tiller number. Statistical analyses demonstrates that the mutant significantly increased the effective tiller number, but both the wild type and mutant decreased the effective tiller number after spraying GA3, indicating that the expression profiles of the D14 gene in rice might be modulated by GA, and thereby exert on the tiller number.【Conclusion】Semi-dwarfed rice mutant is likely caused by a decrease of GA4 enrichment because of abnormal expression of the OsGA13ox gene, and GA might indirectly regulate rice tiller by affecting the expression of the D14 gene.

    TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY
    Effects of Tillage Practices and Irrigation Times on Water Use Efficiency and Grain Yield of Winter Wheat in Lime Concretion Black Soil
    WANG YongHua,LIU Huan,XIN MingHua,HUANG Yuan,WANG ZhuangZhuang,WANG JinFeng,DUAN JianZhao,FENG Wei,KANG GuoZhang,GUO TianCai
    Scientia Agricultura Sinica. 2019, 52(5):  801-812.  doi:10.3864/j.issn.0578-1752.2019.05.003
    Abstract ( 418 )   HTML ( 29 )   PDF (420KB) ( 347 )   Save
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    【Objective】This research was conducted to explore the effects of tillage practices and irrigation times on water use efficiency and grain yield of winter wheat in lime concretion black soil, and to identify an optimal tillage and irrigation combination mode of winter wheat in lime concretion black soil with high yield and water use efficiency simultaneously. 【Method】The two-factor split plot experiment was persistently performed in the lime concretion black soil in the southeast area of Henan province during two continuous winter wheat growing seasons (2015-2017). In this experiment, the two tillage practice treatments, including rotary tillage (RT) and subsoiling (SS), were set as the main treatment. The three soil moisture treatments, including twice irrigation at jointing and anthesis, once irrigation at jointing, no irrigation, expressed as W2, W1, W0, respectively, were set as secondary treatment, deeply exploring the effects of tillage practices and irrigation times and their interaction effects on water use efficiency and grain yield of winter wheat in lime concretion black soil. 【Result】 Tillage and irrigation had obvious regulation effects on water consumption characteristics, water use efficiency and grain yield of wheat in lime concretion black soil. Compared with RT, SS could significantly increase soil water storage consumption, which was beneficial to increase the utilization efficiency of precipitation and irrigation water, and the soil water storage consumption, precipitation and irrigation water use efficiency increased by 13.69%, 7.03%, 6.51% in two-year degrees, respectively. Although increasing irrigation could significantly promote water consumption in winter wheat fields, excessive irrigation resulted in lower water use efficiency. Compared with W1 and W0, the average soil water storage consumption and water use efficiency of W2 decreased by 18.85% and 16.69% in two-year degrees, respectively. The grain yield of SS treatment was significantly higher than that of RT treatment and the yield of the combination treatment subsoiling, and once irrigation at jointing (SSW1) was the highest. Under the same tillage practice, the 1000-grain weight decreased and the number of grains per spike increased with the increase of irrigation times. The variation of grain number per spike in the two years increased firstly and then decreased with the increase of irrigation times. The tillage practice mainly affected the final yield by regulating 1000-grain weight and the irrigation times mainly affected the yield by regulating the grain number per spike and 1000-grain weight, but excessive irrigation would resist the increase of grain number and 1000-grain weight. 【Conclusion】Based on the regulating effects of tillage practices and irrigation times on water use efficiency and grain yield, the SSW1 treatment could help synchronously to improve the grain yield and water use efficiency. This can be an optimal model of tillage and irrigation combination treatment of winter wheat in lime concretion black soil area of southeast Henan province.

    Effects of Basal Fertilization in Strips at Different Soil Depths on Flag Leaf Senescence and Photosynthetic Characteristics, Grain Yield and Fertilizer Use Efficiency of Winter Wheat
    YAN HengHui,WEN Ying,WANG Dong
    Scientia Agricultura Sinica. 2019, 52(5):  813-821.  doi:10.3864/j.issn.0578-1752.2019.05.004
    Abstract ( 395 )   HTML ( 31 )   PDF (461KB) ( 353 )   Save
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    【Objective】Aiming at the problem of low fertilizer utilization rate caused by broadcast fertilization or shallow fertilization in Huang-Huai-Hai Plain of China, this paper provided a basis for improving fertilization technology of high yield and high efficiency of winter wheat in irrigated field of this area.【Method】A 2-year irrigated field experiment was carried out from 2016 to 2018 in winter wheat growth season. Five treatments were set up: No fertilization during the whole growth period (T1); Basal fertilizer was applied in stripes in 8 cm depth (T2), 16 cm (T3) and 24 cm (T4); Basal fertilizer was divided into three parts with the proportion of 1﹕2﹕3 and applied in stripes of 8, 16 and 24 cm depths of soil, respectively (T5). The effects of different fertilization methods on flag leaf senescence characteristics and photosynthetic characteristics, fertilizer use rate and grain yield of winter wheat were studied.【Result】With the increase of fertilization depth, the results showed that superoxide dismutase (SOD) activity, catalase (CAT) activity, soluble protein content, the maximum photochemical efficiency of PSⅡ (Fv/Fm), and actual photochemical efficiency of PSⅡ in the light (ΦPSⅡ) all increased, stomatal conductance enlarged, net photosynthetic rate were increased, while malondialdehyde (MDA) content was reduced after winter wheat flowering. There was no significant difference in senescence and photosynthetic rate characteristics between T4 treatment and T5 treatment, but the grain yield and agronomy efficiency of fertilizer under T5 treatment were significantly increased by 5.4%-6.5% and 26.8%-72.9%. This was the fact that it maintained a high number of kernels and grain weight under the conditions of higher panicle number. 【Conclusion】 On the basis of obtaining a higher number of panicles, layered and in proportion basal fertilization treatment (T5) could delay senescence of flag leaves and increase the photosynthetic capacity of the flag leaves after flowering in irrigated field, thus increase grains per spike, 1000-grain weight and grain yield, and beneficial to the high fertilization high-efficient utilization.

    PLANT PROTECTION
    Genetic Diversity Analysis of Curvularia lunata in Summer Maize in Huang-Huai-Hai Region
    CHANG JiaYing,LIU ShuSen,MA HongXia,SHI Jie,GUO Ning,ZHANG HaiJian
    Scientia Agricultura Sinica. 2019, 52(5):  822-836.  doi:10.3864/j.issn.0578-1752.2019.05.005
    Abstract ( 507 )   HTML ( 33 )   PDF (1676KB) ( 439 )   Save
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    【Objective】The objective of this study is to identify the genetic diversity and relationship of Curvularia lunata , the causal agent of maize Curvularia leaf spot occurred in different regions and years in Huang-Huai-Hai region via molecular techniques, and to provide scientific data for studying the occurrence and prevalence of the disease. 【Method】 The samples collected from five provinces (Henan, Hebei, Shandong, Anhui and Jiangsu) in Huang-Huai-Hai region in 2013, 2016 and 2017 were separated and identified by morphology and molecular biology (ITS and EF-1α sequence analysis). A total of 175 C. lunata strains were obtained. Thirteen highly polymorphic and reproducible ISSR primers were screened out from universal primers developed by Columbia University and were used to amplify the 175 C. lunata strains. Popgen32 software was used to calculate the polymorphism ratio, Shannon’s information index, genetic distance and genetic similarity among populations. UPGMA cluster analysis and principal coordinate analysis based on genetic similarity coefficient were carried out by NTsys 2.10e software, and cluster analysis map and scatter plot were constructed. 【Result】 A total of 105 polymorphic bands were obtained with a polymorphism ratio of 100%. At the group average level, the level of genetic diversity (H) was 0.3867, and Shannon’s information index (I) was 0.5682, indicating that the C. lunata had abundant genetic diversity. The genetic diversity among different geographical populations was different. The genetic diversity of Henan and Anhui populations was the highest, and that of Jiangsu population was low. The flora of the same geographical origin was far away from each other during the year, and the flora from different geographical origins in the same year was relatively close. Cluster analysis showed that the similarity coefficients of all strains were 0.51-0.93. At the similarity coefficient of 0.59 level, 175 strains were divided into 2 groups and 5 subgroups. There were annual differences among the subgroups, gene exchanges among the different geographical populations, and the genetic correlation was high. The results of principal component analysis were consistent with those of cluster analysis, and the strains in the same year were obviously clustered together.【Conclusion】There was a high genetic variation in the pathogen populations causing maize Curvularia leaf spot disease in Huang-Huai-Hai region, and the genetic relationship of the adjacent pathogens was close. The strains from the same area showed a certain genetic distance in different years, while the genetic distance of strains of different geographical origins in the same year was close. The results of the analysis indicated that the main pathogen causing the leaf spot disease of C. lunata was not mainly from local source, they probably came from the southern rice and turf grass or maize production areas of Southeast Asia, but occasionally a few strains that survived on the ground surface could be the initial source of infection in the following year.

    Function of Copper-Resistant Gene copA of Ralstonia solanacearum
    WANG XiaoNing,LIANG Huan,WANG Shuai,FANG WenSheng,XU JingSheng,FENG Jie,XU Jin,CAO AoCheng
    Scientia Agricultura Sinica. 2019, 52(5):  837-848.  doi:10.3864/j.issn.0578-1752.2019.05.006
    Abstract ( 448 )   HTML ( 15 )   PDF (1138KB) ( 322 )   Save
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    【Objective】 Bacterial wilt of plants, caused by Ralstonia solanacearum , is a major soil-borne disease around the world. As an important bactericide to control bacterial diseases such as bacterial wilt, the widespread use of copper-based bactericides has led to the emergence of copper-resistant strains in a variety of plant pathogenic bacterial population. The copper-resistant coding gene copA , homologous with Pseudomonas syringae , was carried on the megaplasmid of R. solanacearum Po82 strain. The objective of this study is to investigate the biological function of copA in copper resistance and pathogenicity of Po82 strain.【Method】The phylogenetic relationship of the copper-resistant gene copA in different strains of R. solanacearum and other phytobacterial strains was analyzed based on neighbor-joining method using MEGA6.0 for constructing the phylogenetic tree of copA . By means of reverse genetics strategy, using the methods of gene homologous recombination and electroporation, copA gene deletion and complementary strains of Po82 were constructed. Copper minimal inhibition concentration (MIC) test, RT-qPCR, Biolog chip analysis, pathogenicity test and other basic biological methods were employed to clarify the relationship between copA and biological characteristics such as response to copper stress, metabolic activity, pathogenicity, and motility of R. solanacearum. 【Result】The results of homology analysis showed that the copA existed widely in the bacterial population, and the copA of R. solanacearum was most closely related to Cupriavidus metallidurans , but far genetic relationship with Xanthomonas oryzae , P. syringae and Escherichia coli . RT-qPCR analysis showed that the expression of copA was induced by copper. The expression of copA increased with the increase of CuSO4 concentration. The expression level of copA was the highest when the CuSO4 concentration was 1.0 mmol·L -1. By MIC analysis, the result showed that the sensitivity of the copA deletion strain to copper was significantly increased. The MIC value of copA deletion strain was 0.8 mmol·L -1, which decreased by 33.3% compared with that of wild-type strain (1.2 mmol·L -1). The complementary strain restored copper resistance. The results indicated that copA played an important role in copper resistance of R. solanacearum . Compared with wild-type strain, the logarithmic growth rate of copA gene deletion strain decreased in both NA medium and NA medium containing 0.6 mmol·L -1 CuSO4, indicating that copA was related to the growth rate of R. solanacearum . The absence of copA resulted in a decrease in the pathogenicity of R. solanacearum . On the 10th day of inoculation, the disease index of the copA gene deletion strain decreased by 11.7% compared with that of the wild-type strain Po82. The absence of copA resulted in a reduction of metabolic utilization rate of carbon sources such as α -D-glucose, D-trehalose and nitrogen sources such as L-alanine and glucuronide. Compared with wild-type strain Po82, the expression level of hrpB , hrpG and ripX genes, which are important components of the type Ⅲ secretion system, was also significantly down-regulated in copA gene deletion strain. 【Conclusion】 The copper-resistant gene copA plays an important role in copper stress response and pathogenicity of R. solanacearum . The results provide a theoretical basis for further analysis of copper resistance mechanism and the control of copper-resistant strains.

    SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT
    The Potential and Related Mechanisms of Increasing Rice Yield by Reducing Chemical Nitrogen Application in Jiangsu Province
    GUO JunJie,CHAI YiXiao,LI Ling,GAO LiMin,XIE KaiLiu,LING Ning,GUO ShiWei
    Scientia Agricultura Sinica. 2019, 52(5):  849-859.  doi:10.3864/j.issn.0578-1752.2019.05.007
    Abstract ( 581 )   HTML ( 23 )   PDF (1804KB) ( 418 )   Save
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    :【Objective】To evaluate the applicability of nitrogen fertilizer reduction and optimization for rice productivity in Jiangsu Province, the current situations and existed problems of fertilizer application were studied, and the effects of reducing nitrogen application on rice yield formation, nitrogen uptake and utilization were quantified.【Method】The current situations of rice nitrogen application rate (chemical nitrogen), grain yield and nitrogen use efficiency (PFPN, Partial factor productivity of applied nitrogen) were conducted by 1 502 farmer surveys in Jiangsu Province. Moreover, the effect of nitrogen reduction on rice productivity was evaluated by using Meta-analysis with 195 observations from 49 previous published studies. 【Result】The data of farmer practices survey showed that the averaged rice yield, nitrogen application rate and PFPN in Jiangsu Province were 8 273 kg·hm -2, 358.10 kg·hm -2 and 25.12 kg·kg -1, respectively. Meta-analysis showed that after reducing the N rate, the yield and PFPN increased by 2.8%-5.7% and 52.4%-77.0%, respectively, compared with traditional/conventional nitrogen application in Jiangsu province. The increased rice yield and PFPN were attributed to the regulated nitrogen uptake (-5.8%- -14.0%), which reducing the rice panicle number by 2.09%-5.46%, while increasing the grains per panicle, seed setting rate and 1000-grain weight by 3.96%-6.79%, 2.00%-3.88% and 0.89%-2.10%, respectively. The enhancing effects of reducing nitrogen application on rice yield and nitrogen efficiency in indica rice were higher than those of japonica rice. Reducing the nitrogen application based on reasonable nutrient management combined with organic matter (straw) input had the best effects (high yield and high nutrient efficiency). Present study also showed that the best reduction proportion of nitrogen application was supposed to lower than 25%. Moreover, the soils with high fertility were more conducive to achieve nitrogen fertilizer reduction with ensured rice yield. Taken together, the nitrogen reduction of rice in Jiangsu province could be realized by adjusting the nitrogen management and applying organic fertilizer. The recommended reduction space of nitrogen fertilizer was 31%, in which the basal and tillering fertilizers were the main decreasing direction. 【Conclusion】The reduction of chemical nitrogen fertilizer application of rice in Jiangsu province could be achieved while the basal fertilizer and tillering fertilizer should be most considered. The yield components of rice could be controlled reasonably, and the yield and nitrogen utilization efficiency of rice could be improved by reducing nitrogen application when controlling the reduction of nitrogen fertilizer within 31% and combined with optimizing management.

    Temporal and Spatial Variation Characteristics of Phosphorus Element Flows in the Crop-Livestock Production System of Hainan Island
    DING Shang,GUO HaoHao,SONG ChenYang,DIAO XiaoPing,ZHAO HongWei
    Scientia Agricultura Sinica. 2019, 52(5):  860-873.  doi:10.3864/j.issn.0578-1752.2019.05.008
    Abstract ( 358 )   HTML ( 17 )   PDF (1253KB) ( 329 )   Save
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    【Objective】 The objective of this study is to analyze the temporal and spatial characteristics of phosphorus flows and its environmental effects in the crop-livestock production system of Hainan Island from 1987 to 2016, research its flow process and discipline, discuss the optimized management approach of phosphorus in the crop-livestock production system, and to provide a scientific basis for the development of farming and animal husbandry in Hainan Island.【Method】The study was based on the NUFER model (NUtrient flows in Food chains, Environment and the Resources use). Data statistics, literature search and field investigation as well as the software such as Origin were used to calculate phosphorus input, output, efficiency and environmental effects of the crop-livestock production system in Hainan Island. Potentially sustainable phosphorus utilization approaches were explored through scenario analysis of the crop-livestock production system.【Result】In the past 30 years, the total input of phosphorus in the farming subsystem of Hainan Island increased from 21.34 to 81.19 Gg, and the total output increased from 6.20 to 18.20 Gg. As the main source of phosphorus in the system, the input of chemical fertilizer increased from 19.01 to 79.23 Gg. Crop products as the main export of farmland phosphorus, and from 5.25 Gg to 15.48 Gg in 30 years. The total input of phosphorus in the animal production subsystem increased from 11.40 to 15.31 Gg, and the total output increased from 9.63 to 11.90 Gg, in which the input of imported feed phosphorus increased from 10.97 Gg in 1987 to 14.77 Gg in 2016, and the output of animal products increased by 4.95 Gg in 30 years. The amount of crop straw to the field and the local feed increased by 0.37 and 0.26 kg·hm -2, respectively, while the amount of manure to the field decreased by 0.80 kg·hm -2. In terms of spatial distribution, the input and output amounts of phosphorus in Chengmai and Dingan were relatively higher in the past 30 years, while those in Wuzhishan and Qiongzhong were relatively lower. In terms of phosphorus loss, the amount of soil phosphorus surplus per unit cultivated land of Hainan Island increased from 35.00 to 147.40 kg·hm -2 in 1987-2016. In 2016, the amount of soil phosphorus surplus of Qionghai, Chengmai, Baoting and Lin’gao was relatively higher, which was 372.79, 279.82, 194.14 and 181.09 kg·hm -2, respectively. The other loss ways of phosphorus were soil erosion, runoff and leaching, the loss amounts were from 1.21 to 5.85 kg·hm -2. The carrying capacity of livestock and poultry manure of cultivated area was maintained at 3.83-5.77 kg·hm -2. In the past 30 years, phosphorus use efficiency in the farming production subsystem increased from 13.01% to 13.86%, phosphorus use efficiency in the animal production subsystem increased from 4.78% to 7.62%, and phosphorus use efficiency in the crop-livestock production system increased from 10.78% to 13.09%. The result of scenario analysis showed that it was of great significance to promote the coordinated development between the farming production subsystem and the animal production subsystem of Hainan Island and to improve the recycling utilization rate of resources through scientific nutrient management.【Conclusion】Affected by the scale of the crop-livestock production system, regional development and management mode, the environmental loss of the crop-livestock production system was serious, the phosphorus use efficiency was relatively low, and the system was seriously separated in Hainan Island. Therefore, in the future crop-livestock production in Hainan Island, technical means and management measures should be optimized, such as controlling excessive input of phosphorus, reducing the direct discharge of manure, and improving the phosphorus cycle efficiency of straw and manure. At the same time, the coordination relationship between the farming production subsystem and the animal production subsystem should be promoted, and the sustainable development road of combination of farming and animal husbandry should be carried out.

    Effects of Sulfur Fertilizer on Boron Uptake and Distribution of Rape in B-contaminated Soil
    LI MingFeng,LIU XinWei,WANG HaiTong,ZHAO ZhuQing
    Scientia Agricultura Sinica. 2019, 52(5):  874-881.  doi:10.3864/j.issn.0578-1752.2019.05.009
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    【Objective】This study explored the effects of sulfur (S) fertilizer application on B uptake and distribution in rapeseed under high boron (B) environment, and provided a theoretical basis for rational application of S fertilizer to alleviate B toxicity in rapeseed (Brassica napus L.). 【Method】Rape plants (cv. Huayouza 9) were grown in pots filled with calcareous alluvial soil contaminated with B (total B content: 13.44 mg·kg -1; available B: 5.07 mg·kg -1) and the effects of S fertilizer level (0, 20, 50, 100, 200, and 500 mg·kg -1) on B concentration, distribution, cell wall extraction rate, cell wall B concentration and its proportion of total B in different parts of the rape were determined at the podding stage. 【Result】 With the increase of S application, the biomass increased at first and then decreased in different parts of rape. When the S was applied at 50 mg·kg -1, the fresh biomass of rape was the largest, reached 364.5 g/plant under different S application, and the B concentration and distribution in different parts of rape followed the order of pods>leaves>stems>roots, which indicated that the pods were the main accumulation site of B. As the S fertilizer level increased from 0 to 100 mg·kg -1, the pod B concentration and distribution ratios decreased by 14.8% and 15.0%, respectively. The extraction rate of cell wall of rapeseed pods increased by 43.0%, and there was no significant change in the B concentration and proportion in the cell wall. When S fertilizer was continuously applied to 200 mg·kg -1, the B concentration, distribution ratios and cell wall B concentration of rapeseed pods decreased significantly, and cell wall B proportion increased significantly compared with that of non-sulfur fertilizer. The opposite trends were found in the B concentrations and cumulative distribution ratios in the leaves, stems and roots. As the S fertilizer level increased from 0 to 100 mg·kg -1, the B concentration significantly increased by 15.0%, 32.9% and 34.9% in rape leaves, stems, and roots, respectively. The B distribution ratios significantly increased by 13.4%, 29.6% and 18.6%, and B concentration in the cell wall significantly increased by 12.3%, 22.9% and 14.9% in rape leaves, stems, and roots, respectively. It showed that the addition of S fertilizer increased the B concentration of the leaves, stems and roots of rapeseed. 【Conclusion】S fertilizer application effectively alleviated B toxicity by increasing biomass, limiting B translocation from roots, stems and leaves to pods, and by increasing the extraction rate of cell wall in rape plants grown on B-contaminated soil. The optimum amount of S fertilizer application was 50-100 mg·kg -1.

    HORTICULTURE
    Cloning and Expression Analysis of SERK2 Gene in Different Forms of Calli on Peach (Prunus persica L.)
    TAN Bin,CHEN TanXing,HAN YaPing,ZHANG YaRu,ZHENG XianBo,CHENG Jun,WANG Wei,FENG JianCan
    Scientia Agricultura Sinica. 2019, 52(5):  882-892.  doi:10.3864/j.issn.0578-1752.2019.05.010
    Abstract ( 467 )   HTML ( 16 )   PDF (7277KB) ( 336 )   Save
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    【Objective】The somatic embryogenesis receptor-like kinase 2 (SERK2 ) gene was isolated and cloned from peach (Prunus persica L.). Here, we detected the expression profile of SERK2 in different forms of calli in peach, and analyzed the correlation between SERK2 and the regeneration of embryonic callus. This research will shed on uncovering the molecular mechanism of embryonic callus induction and regeneration in peach with difficulty on tissue culture. 【Method】The full-length cDNA sequence of PpSERK2 gene was obtained by homologous cloning. Then the sequence was analyzed by a series of bioinformatical software packages, including TMPred, DNAMAN and MEGA 5.0 etc. The callus of ‘Qiumihong’ was obtained by using anthers as explants inoculated into NN69 medium supplemented with 2.0 mg·L -1 6-BA and 1.0 mg·L -1 2,4-D. Then the different forms of calli were observed by production of paraffin section. Real-time quantitative PCR (qRT-PCR) was used to analyze the expression of PpSERK2 gene in four forms of ‘Qiumihong’ calli. 【Result】The full-length cDNA sequence of PpSERK2 gene was 1 881 bp. It encodes 626 amino acids and contains SERK conserved function domains. The theoretical isoelectric point of PpSERK2 is 5.38 and its molecular weight is 68.99 KD. The PpSERK2 has the high homology similarity from 67.88% to 92.71% at protein level, especially the highest similarity to Solanum peruvianu and Citrus unshiu . The phylogenetic analysis of SERK proteins from various plant species indicated that PpSERK2, SpSERK1, CitSERK1 and PsSERK2 were clustered together, which showing the consistent result with above protein similarity analysis. Four different forms of calli were obtained from anther of ‘Qiumihong’. The results of histocytology showed that the cells of three forms of calli, including the yellow, loose callus (global embryo), green, compact callus (heart embryo) and pale yellow, transparent callus (suspected torpedo embryo), were small and closely arranged. While the cells of yellow-white, dropsical callus was large and with irregular shapes. Based on histomorphology results, this demonstrated that the yellow, loose callus, green, compact callus and pale yellow, transparent callus were embryonic calli, while yellow-white, dropsical callus was non-embryonic callus. The results of qRT-PCR showed that transcriptional level of PpSERK2 gene in three forms of embryonic calli was remarkably higher than non-embryonic callus. Meanwhile, the transcriptional level of PpSERK2 gene was highest in the yellow, loose callus, followed by the green, compact callus, and lowest in the pale yellow and transparent callus of ‘Qiumihong’. 【Conclusion】The full-length cDNA of the PpSERK2 gene was successfully obtained. According to the results of PpSERK2 expression in four forms calli of ‘Qiumihong’, we speculated that PpSERK2 gene might play a pivotal role on the early stage during the somatic embryogenesis in peach.

    Effects of Nitrogen Application Levels on Nutrient, Yield and Quality of Tarocco Blood Orange and Soil Physicochemical Properties in the Three Gorges Area of Chongqing
    YANG JiangBo,ZHANG Ji,LI JunJie,ZHENG YongQiang,LÜ Qiang,XIE RangJin,MA YanYan,DENG Lie,HE ShaoLan,YI ShiLai
    Scientia Agricultura Sinica. 2019, 52(5):  893-908.  doi:10.3864/j.issn.0578-1752.2019.05.011
    Abstract ( 373 )   HTML ( 18 )   PDF (565KB) ( 268 )   Save
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    【Objective】 This study investigated effects of different nitrogen application levels on nutrient uptake, fruit yield and quality, soil physical and chemical properties of late ripening citrus Tarocco blood orange in typical citrus orchards to provide a theoretical basis for the high-quality and high-yield of late-maturing citrus in the Three Gorges area of Chongqing city. 【Method】 Six different nitrogen treatments (N0 (0), N1 (1 kg/plant), N2 (1.5 kg/plant), N3 (2 kg/plant), N4 (2.5 kg/plant) and N5 (3 kg/plant)) were performed to study its effects on nutrient absorption of branches and leaves and fruit, fruit quality and yield and soil physicochemical properties using 7-year-old Tarocco blood orange grafted on Poncirus trifoliata (L.). 【Result】 Results showed that the increased nitrogen levels except N2 group significantly increased the dry matter amount of leaves and branches in different periods of blood orange with higher level in spring shoots than autumn shoots as well as higher level in leaves than branches. The nutrient absorption of nitrogen, phosphorus and potassium in spring shoots was the lowest under N0 treatment, and the absorption of nitrogen in leaves was significantly increased by the added nitrogen fertilizer with a peak level under N2 treatment while the absorption of phosphorus and potassium with a peak level under N3 treatment. Nitrogen application significantly increased the amount of nitrogen uptake of leaves and branches of autumn shoots with a maximum level under N5 treatment. High nitrogen treatments (N3-N5) significantly increased the amounts of phosphorus and potassium uptake of leaves and branches. Nitrogen first increased then decreased the nitrogen and potassium content of fruit with the maximum level under N2 treatment. The content of nitrogen and potassium in pulp was much higher than that of peel, while the phosphorus content was opposite. The maximum nutrient removal amount of nitrogen, phosphorus and potassium was found under N2 treatment with a significant increase, and the amount of nutrient removal was potassium>nitrogen>phosphorus. The pH value and content of organic matter of soil decreased significantly by adding nitrogen fertilizer while the content of available nitrogen and phosphorus of soil increased significantly with the maximum available potassium content under N3 treatment. Nitrogen increased the leaching of nitrate nitrogen in soil within 0-20 cm with the highest level under N2 treatment. Ammonium nitrogen was positively correlated with the nitrogen application rate. There was no significant difference among the content of nitrate nitrogen and ammonium nitrogen under all treatments within 20-40 cm soil layer. The content of nitrate nitrogen in 40-60 cm soil layer increased significantly under high nitrogen treatments, while the ammonium nitrogen content did not change. Nitrogen application first enhanced the thickness of pericarp, the longitudinal diameter, transverse diameter, average weight and yield, and then decreased with the highest level of the longitudinal and transverse diameter under N3 treatment and the highest weight and yield under N2 treatment. Nitrogen application first increased then decreased the total soluble solid (TSS) content without significant difference. Nitrogen input increased titratable acid (TA) content and but decreased TSS/TA ratio. N2 group had the highest vitamin C and anthocyanin content. Fruit coloration was relatively good between N2 and N3 treatments. Correlation analysis showed that the nitrogen content in leaves was positively corrected with the TA content of fruit and the thickness of pericarp, and negatively correlated with the ratio of TSS/TA, and the content of available N in soil was positively correlated with TA content and pericarp thickness, which was significantly negatively correlated with TSS/TA ratio of fruit.【Conclusion】Considering and analyzing, in the citrus orchard of the Three Gorges area of Chongqing, the recommended pure nitrogen application rate was ranged from 0.63 to 0.86 kg/plant which can guarantee a high level of yield and fruit quality, and is beneficial to the nutrient absorption and utilization of blood orange tree, while the risk of orchards’ soil environmental pollution was relatively low.

    FOOD SCIENCE AND ENGINEERING
    Eating Quality and Physicochemical Properties in Nanjing Rice Varieties
    ZHAO ChunFang,YUE HongLiang,HUANG ShuangJie,ZHOU LiHui,ZHAO Ling,ZHANG YaDong,CHEN Tao,ZHU Zhen,ZHAO QingYong,YAO Shu,LIANG WenHua,LU Kai,WANG CaiLin
    Scientia Agricultura Sinica. 2019, 52(5):  909-920.  doi:10.3864/j.issn.0578-1752.2019.05.012
    Abstract ( 977 )   HTML ( 29 )   PDF (466KB) ( 943 )   Save
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    【Objective】 The aim of this study was to confirm the main characteristics of cooking and eating quality in three Nanjing rice varieties and to clarify the differences between them and their parents, so as to provide theoretical basis for improvement of high grain quality rice varieties. 【Method】 Three Japonica rice varieties (Nanjing 46, Nanjing 9108, Nanjing 5055) and their parents (Kanto 194, Wujing 13 and Wuxiangjing 14) were used as experimental materials. Twenty-five eating quality related traits, including physicochemical characteristics, amylopectin branching structure, RVA spectrum properties, thermal properties and taste characteristics of cooked rice, were measured and the differences were compared among the six rice varieties. The relationships between physicochemical properties and taste characteristics of cooked rice, and between chemical composition, amylopectin structure and functional characteristics were analyzed. 【Result】 Three Nanjing japonica rice varieties were consistent in the most of the investigated traits. Compared to Wujing 13 and Wuxiangjing 14, three Nanjing varieties contained lower amylose content, peak time, though, final, setback and consistent viscosity, retrogradation enthalpy and rate, and hardness of cooked rice, and higher gel consistency, breakdown viscosity, stickiness and comprehensive value of cooked rice. In amylopectin structure, the proportion of A-chain (DP6-12) was higher, while that of B1-chain (DP13-24) was smaller. The three Nanjing varieties were more similar to Kanto 194 in most of the investigated traits, indicating that the eating quality traits of three Nanjing varieties were inherited from Kanto 194. There were differences among three Nanjing varieties, Nanjing 46 had lower protein content and thermal parameters, Nanjing 9108 contained higher lipid content, and Nanjing 5055 had higher pasting temperature than other two Nanjing varieties. Correlation analysis showed that except for protein content, gelatinization temperature and peak time, significant or extremely significant correlations between the comprehensive value of cooked rice and most of physicochemical properties were identified. Further analysis showed that physicochemical characteristics of rice were mainly contributed by amylose content. 【Conclusion】 The excellent eating quality characteristics of three Nanjing rice varieties have been mostly attributed to lower gelatinization and retrogradation, higher gel consistency and stickiness, shorter gelatinization time and greater breakdown. Lower amylose content was the main cause for high taste quality formation of cooked rice, whereas protein content and amylopectin branching ratio played roles in gelatinization and retrogradation.

    ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT
    Selection of Nucleus Herd for Simmental Cattle in Xinjiang Area
    WEI Chen,ZHAO Junjin,HUANG XiXia,YANG HongJie,ZHANG MengHua,GE JianJun,MA GuangHui,ZHANG XiaoXue,WANG Dan,YOU ZhenChen,XU Lei,JIANG Hui,ZHAO FanFan,JU Xing,LI YunXia
    Scientia Agricultura Sinica. 2019, 52(5):  921-929.  doi:10.3864/j.issn.0578-1752.2019.05.013
    Abstract ( 458 )   HTML ( 16 )   PDF (422KB) ( 316 )   Save
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    【Objective】In recent years, the genetic improvement of Simmental cattle in Xinjiang has achieved certain effects, however, the genetic evaluation work has been carried out less. In order to accelerate the genetic progress of Simmental cattle, this study aims to constitute and optimize the suitable breeding program of Simmental cattle in Xinjiang by using genetic evaluation, combined with genetic trend analysis to select nucleus herd and compare the results of TPI selection and single-trait selection.【Method】The research date including the production performance records, DHI testing, mature cow weight and type classification records of 2 495 Simmental cattles, were collected from Xinjiang Hutubi Herd farm during 1974 to 2014. The DMU software was applied together with AI-REML of EM algorithm and multiple-trait animal models to estimate the variance components and breeding values of 305 MY, MFP, MPP, MLP, TS, SCS, MCW and TC. The genetic trend analysis was perfromed in 305MY, MFP, MPP, SCS and MCW. Finally, bulls and nucleus herd cows were selected by TPI.【Result】The results showed that Simmental cattle heritabilities of 305 MY, MFP, MPP, MLP, TS, SCS, MCW and TC were 0.39, 0.15, 0.12, 0.12, 0.32, 0.09, 0.60, 0.19, respectively. 305 MY, TS and MCW were high heritability (h 2>0.3) ; MFP, MPP, MLP and TC were medium heritability (0.12<0.3 ), and SCS was low heritability (h 2<0.1). Genetic trend of 305MY did not change significantly from 1974 to 2007, and appeared obviously increasing trend from 2008 to 2012. Between 1974 and 2006, genetic trends of MFP and MPP showed a slightly downward trend, and appeared obviously increasing trend from 2007 to 2013. Genetic trend of SCS appeared obviously increasing trend from 1974 to 2000, and an upward trend from 2001 to 2012 is shown. Genetic trend of MCW had a big fluctuation from 1974 to 2007, and appeared obviously increasing trend from 2008 to 2011. Breeding values for bulls and herd cows were ranked according to total performance index.The TPI value of the first bull was 552.45, and average of top 10 bulls was 383.41. Average TPI value of 100 nucleus herd cows was 214.91. Average value of 305MY, MFP, MCW and TC phenotype values of 100 Average TPI value of 100 nucleus herd cows were 7 095.10 kg, 4.13%, 696.53 kg and 76.73, respectively, which was higher than average of phenotype value in herd cows. The breeding values appeared to be different among single-trait selection and TPI . It is concluded that TPI selection was better than single-trait selection.【Conclusion】Recently, gentic trends of 305MY, MPF, MPP and MCW of Simmental cattle were appeared obviously increasing trend, and SCS was a downward trend, which further proved that breeding and genetic improvement of Simmental cattle had achieved certain results. By comparing the differences between TPI selection and single-trait selection, it is proved that selection index was more practical in production, and farm will use more bulls with high TPI values. And the population of cattle group will be expanded on the basis of 100 nucleus herd cows. By selecting excellent bulls for breeding and expanding group, the purpose was improved production of the whole group in Simmental cattle.

    Immunogenicity Evaluation of Eukaryotic Expressing Plasmids Encoding HA Protein of Eurasian Avian-Like H1N1 Swine Influenza Virus
    JIA YunHui,XU ChengZhi,SUI JinYu,WU YunPu,XU BangFeng,CHEN Yan,YANG HuanLiang,QIAO ChuanLing,CHEN HuaLan
    Scientia Agricultura Sinica. 2019, 52(5):  930-938.  doi:10.3864/j.issn.0578-1752.2019.05.014
    Abstract ( 711 )   HTML ( 18 )   PDF (1951KB) ( 107 )   Save
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    【Objective】This study aimed to construct the recombinant plasmid expressing HA gene of Eurasian avian-like H1N1 (EA H1N1) swine influenza virus (SIV) and then evaluate its immunogenicity in mice. 【Method】HA gene of A/swine/Zhejiang/ 245/2013(H1N1) (ZJ245) was amplified by RT-PCR, and inserted into an eukaryotic expression vector pCAGGS. The recombinant plasmid, designated as pCAGGS-HA(ZJ245), was transfected into 293T cells, and the expressed HA protein was identified by indirect fluorescence assay (IFA) and Western blot. In order to evaluate the immunogenicity of the recombinant plasmid pCAGGS- HA(ZJ245), sixteen six-week-old female BALB/c mice were immunized with 100 μg of the recombinant plasmid by intramuscular injection, and then were boosted once with a 3-week interval. Another group of sixteen mice received 100 μL of phosphate-buffered saline (PBS) were used as unvaccinated control. Serum samples were collected every week after prime and boost immunization in order to detect the hemagglutinin inhibition (HI) antibodies, virus neutralization (VN) antibodies, respectively. Two weeks after the boost immunization, pCAGGS-HA(ZJ245)-immunized and PBS-inoculated mice were intranasally challenged with 50 μL(10 6.0EID50) of the homologous ZJ245 and heterologous A/swine/Heilongjiang/44/2009(H1N1) (HLJ44), respectively. All mice per group were monitored daily for clinical signs of infection and body weight changes for two weeks. The mice that lost more than 25% of their initial body weight were euthanized on humane ground. On day 3 post-challenge three mice per group were euthanized and their organs including brain, nasal turbinate, lung, spleen and kidney were collected for virus titration in eggs. Immune efficacy of the recombinant plasmid pCAGGS-HA(ZJ245) was evaluated by body weight loss and virus replication titer in mice, respectively. 【Result】The recombinant plasmid pCAGGS-HA(ZJ245) was constructed by inserting HA gene of ZJ245 virus and verified by restriction endonuclease analysis and plasmid sequencing. IFA and Western blot analysis confirmed that the HA protein could be correctly expressed by the recombinant plasmid pCAGGS-HA(ZJ245) and had a good biological activity in vitro. Immunization and challenge trial indicated that low levels of HI and VN antibody against the homologous ZJ245 virus were initially detected one week after the first immunization, and significantly increased after the second immunization, with the HI titer of 76.88 and the VN titer of 152.5, respectively. Meanwhile, low levels of HI and VN antibodies against the heterologous HLJ44 virus were also detected. Compared with PBS-inoculated mice, the weight loss and viral replication rate of the pCAGGS-HA(ZJ245)-vaccinated mice when challenged with 10 6.0EID50 of the homologous ZJ245 virus were completely inhibited. When challenged with 10 6.0EID50 of the heterologous HLJ44 virus, the extent of weight loss and viral titer of the challenge virus detected in the pCAGGS-HA(ZJ245)- vaccinated mice were significantly lower than those in the PBS-inoculated mice (P<0.0001, P<0.001, P<0.05).【Conclusion】The recombinant plasmid pCAGGS-HA(ZJ245) could efficiently express HA protein, and provided complete protection for the immunized mice against the homologous ZJ245 virus infection and partial cross-protection against the heterologous HLJ44 virus infection, which indicated that the recombinant plasmid pCAGGS-HA(ZJ245) had good immunogenicity.

    Antioxidative and Anti-inflammatory Activities of Ethanol Extract of Geopropolis from Stingless Bees
    WANG Bei,CHANG HuaSong,SU SongKun,SUN LiPing,WANG Kai
    Scientia Agricultura Sinica. 2019, 52(5):  939-948.  doi:10.3864/j.issn.0578-1752.2019.05.015
    Abstract ( 612 )   HTML ( 30 )   PDF (742KB) ( 646 )   Save
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    【Objective】Stingless bees are one of the important pollinators in tropic and subtropical area, differ from Apis mellifera ligustica with typical stingless characteristic. Stingless bee collected more propolis than that of A. m. ligustica . Nevertheless, the study on the geopropolis activity was relatively scarce. The objective of this study is to evaluate the in vitro antioxidant and anti-inflammatory activities of the ethanol extract of geopropolis collected from stingless bee, Heterotrigona itama , which is an indigenous stingless bee species in Malaysia. 【Method】The content of total phenolic acid and total flavonoids in the EEHI (ethanol extract of H. itama propolis) was determined by Folin-phenol method and AlNO3 colorimetry, respectively. The antioxidant activity was investigated using DPPH and ABTS free radical scavenging assays. Moreover, the inflammatory model of murine macrophage RAW 264.7 was induced by bacterial endotoxin lipopolysaccharide (LPS) and the effect of EEHI on the relative cell viability was detected via CCK-8 method. On the basis of ensuring that EEHI has no cytotoxic effect on cells, Griess method and RT-qPCR technique were applied to evaluate the effect of EEHI on the release of inflammatory mediator NO, and on the expression of inflammatory factors ( IL-1β , IL-10 and INOS ) as well as antioxidant gene ( HO-1 ) in LPS-activated macrophages, respectively. In order to explore the potential anti-inflammatory mechanisms of EEHI, the effects of EEHI on the expression of p-IκB α and IκΒ α in macrophages induced by LPS and the translocation of NF-κB-p65 protein were further studied by Western blot and immunofluorescence methods. 【Result】The content of total phenolic acid and total flavonoids in the EEHI was 54.70 mg GAE·g -1 and 116.20 mg QE·g -1, and the IC50 value of the EEHI for scavenging of DPPH and ABTS free radicals was 275.60 and 284.00 μg·mL -1, respectively. The safe concentration of EEHI to RAW 264.7 cells was 0-40 μg·mL -1. In LPS-challenged macrophages, EEHI at 0-40 μg·mL -1 significantly inhibited the release of NO as well as the expression of pro-inflammatory cytokine genes ( IL-1β , IL-10 and INOS ), and enhanced the expression of antioxidant gene HO-1 in a dose-dependent manner, compared with the LPS-treated control. Furthermore, it was noticed that EEHI at 0-40 μg·mL -1 significantly inhibited the LPS-stimulated phosphorylation of IκΒ α protein in a dose-dependent manner, and EEHI at 40 μg·mL -1 significantly reduced the nuclear migration of NF-κB-p65 protein. It was suggested that EEHI had potential anti-inflammatory effects by inhibiting the activation of NF-κB inflammatory signaling pathway induced by LPS.【Conclusion】The ethanol extract of geopropolis collected from H. itama contains a large number of polyphenols, which has good antioxidant and anti-inflammatory effects, and is of great value for exploitation and utilization in the future.

    RESEARCH NOTES
    Genetic Analysis of Sex-Linked Plumage Color Traits of Goose
    YU JinCheng,LI Zhe,YU Ning,LIU Kuang,ZHAO Hui
    Scientia Agricultura Sinica. 2019, 52(5):  949-954.  doi:10.3864/j.issn.0578-1752.2019.05.016
    Abstract ( 473 )   HTML ( 23 )   PDF (333KB) ( 266 )   Save
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    【Objective】The Huoyan breed of geese is a famous white goose breed in China, 1-day-old gosling of the Huoyan goose are yellow or light yellow. In the offspring of the free mating group, 20% of 1-day-old goslings were found to have a light brown variation during Huoyan goose breeding process, and the ratio of male to female is obviously different (the ratio of male to female is close to 1﹕3), it is speculated that there is a sex-linked inheritance tendency in goose plumage color trait. Using the light brown male geese and yellow female geese as the parents, the hybrid experiment was used to test whether the phenotype of the gosling downy feathers conformed to the Mendelian inheritance law, so as to understand the genetic mechanism of goose plumage color trait. The study on the inheritance and mechanism of feather color traits of goose is of great significance for the breeding of new breeds or strains of goose and the goose specialized line cultivation of auto-sexing by feather color. 【Method】40 males and 200 females of Huoyan geese were chosen to generate the G1 generation of Huoyan goose pure line by random mating, and plumage color appearance and segregation ratio in G1 were observed. 4 light brown males and 20 white feather color females of Huoyan geese were chosen to generate the F1 generation, and plumage color appearance and segregation ratio in F1 were observed. 【Result】① In the random mating G1 generation of the Huoyan goose, the proportion of light brown downy feather trait individuals was 19.5%. Among them, the ratio of light brown individuals between male and female chicks is relatively large, the proportion of light brown in male chicks is about 10%, and 30% of females are light brown. According to Hardy-Weinberg’s law, the allele frequency of the color traits of the downy feather is calculated as follows: The ratio of light brown individuals in the female goslings is the frequency of the light brown trait alleles in the Huoyan goose population, in this experiment, 29.8% of the female are light brown, so the frequency of the light brown trait allele is about 0.3. At the same time, the ratio of the light brown individual in the male goslings can also calculate the frequency of the light brown allele, in this case, 10% of the male are light brown, so the frequency of the light brown trait allele is about 0.3. Correspondingly, the frequency of the yellow downy feather trait allele is about 0.7. ②Among the F1 populations, 81 were yellow feathers, accounting for 50%; 79 were light brown, accounting for 50%. And the yellow feathers are all male, and the light brown feathers are all female. The results showed that the light brown traits were associated with sex-linked inheritance. It has been confirmed that silver feather (S*S) and imperfect albinism (S*AL) are controlled by a pair of alleles located on the Z chromosome, and the imperfect albinism gene AL is recessive to the silver feather gene S. Therefore, based on the results of the hybridization test, it can be concluded that the light brown and yellow are the results determined by the multiple allele of one locus, and the light brown color is recessive inheritance for the yellow trait.【Conclusion】In this experiment, the separation of 1-day-old goslings feather phenotypes was analyzed by downy feather color matching hybridization and random mating test. The results showed that the light brown downy feather color trait of Huoyan goose exhibits recessive heredity to the yellow, and demonstrates sex-linked inheritance. The downy feather color of the Huoyan goose is mainly controlled by the Z chromosome silver feather locus. The variation site of the allele controlling the locus is associated with the corresponding appearance.