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    16 May 2019, Volume 52 Issue 10
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Genetic Analysis and Characterization of Hormone Response of Semi-Dwarf Mutant dw-1 in Brasscia napus L.
    SONG Xi, PU DingFu, TIAN LuShen, YU QingQing, YANG YuHeng, Dai BingBing, ZHAO ChangBin, HUANG ChengYun, DENG WuMing
    Scientia Agricultura Sinica. 2019, 52(10):  1667-1677.  doi:10.3864/j.issn.0578-1752.2019.10.001
    Abstract ( 570 )   HTML ( 49 )   PDF (865KB) ( 464 )   Save
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    【Objective】 Plant height has an great effect on lodging resistant, productivity and mechanical operation in rapeseed. Identification and research of dwarf and semi-dwarf germplasm in rapeseed will facilitate genetic improvement of plant height. At present, excellent dwarf germplasm in rapeseed is seriously deficient. In this study, we obtained a semi-dwarf natural mutant in B. napus and it was evaluated by phenotypic identification, genetic analysis and morphological and physiological analysis correlated to plant hormone. This work provide a theoretical basis for dwarf breeding and will contribute to further gene mapping and cloning.【Method】 A semi-dwarf mutant discovered from rapeseed line 141492 after six generations of self-crossing was used to produce DH population by isolated microspores culture, from which we choose one named dw-1 with the average plant height of 95 cm (83-105 cm) to identify its performance on agronomic traits, economic traits and disease resistance. Joint segregation analysis of six generations derived from a cross between dw-1 and wild type was carried out to reveal the inheritance of plant height based on major gene plus polygene mixed model. Morphology analysis of light and dark treatment (16 hL/8 hD, 24 hD) and exogenous gibberellins sensibility test of hypocotyls and stems were performed to classify the mutant. 【Result】 Compared with wild type, 1000-seed weight did not change while disease index of sclerotinia stem rot, number of secondary braches and number of siliques per plant increased significantly or extremely significantly in dw-1. Length of main inflorescence, number of primary branches, plant height, branch height, height of gravity center, number of siliques on main inflorescence, seeds per silique and yield per plant decreased significantly or extremely significantly and growth duration was shortened remarkably. Genetic analysis indicated that dw-1 was controlled by a pair of major gene with additive-dominant effects plus polygene with additive-dominant-epistasis effects (D-0 model). Additive effect and degree of dominance of major gene were -47.5 and 0.2, respectively. The heritability of major gene in B1, B2, F2 population were 76.0%, 84.0% and 85.0%, respectively, and those of polygene were 4.1%, 5.6% and 6.7%, respectively. Morphogenesis of dw-1 was normal and the length of hypocotyl of dw-1 was decreased significantly compared with the wild type regardless of light or dark condition (P < 0.01). Exogenous gibberellic acid 3 (GA3) with lower concentration had no obvious effect on elongation of hypocotyls and stems in dw-1 while they could be partially rescued in higher concentration but not to the wild type phenotype. 【Conclusion】 Mutant dw-1 with good comprehensive performance was mainly controlled by one pair of additive-dominant major gene dominated by additive effect. Selection of plant height can be carried out in earlier generation of conventional hybridization breeding. dw-1 was unrelated to brassinosteroid (BR) pathway and showed a reduced response to GA3.

    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Cloning and Functional Characterization of Sesame SiSAD Gene
    ZHOU Rong,LIU Pan,LI DongHua,ZHANG YanXin,WANG LinHai,ZHANG XiuRong,WEI Xin
    Scientia Agricultura Sinica. 2019, 52(10):  1678-1685.  doi:10.3864/j.issn.0578-1752.2019.10.002
    Abstract ( 496 )   HTML ( 30 )   PDF (2920KB) ( 371 )   Save
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    【Objective】 Sesame SiSAD (△9 stearoyl acyl-carrier-protein desaturase) gene was cloned and the expression of it was detected. It was transformed into Arabidopsis to investigate its role in the oleic acid synthesis. This study aims to provide molecular basis for the genetic improvement of sesame oleic acid content. 【Method】Total RNA was extracted from leaf of the variety Zhongzhi13 and then was reverse transcripted into cDNA. Using the primers that designed according to the reference genome, the coding region sequence of SiSAD was obtained by RT-PCR. The sequence was further compared with the reference genome. The conserved motifs of SiSAD protein were identified by InterPro and the homologous proteins of SiSAD were recognized by BLAST. A phylogenetic tree of SiSAD from sesame, Olea europaea var. sylvestris, Ipomoea nil, Ricinus communis, Lactuca sativa, Vitis vinifera, Citrus sinensis and Arabidopsis thaliana was constructed by neighbor-joining method to reveal the relationship of SiSAD protein in these species. Expression profiles of SiSAD in roots, stems, leaves, buds and seeds at two varieties Zhongzhi33 and Zhongfengzhi No.1 were investigated. The SiSAD gene was linked to a 35S vector and transformed into Arabidopsis by the Agrobacterium tumefaciens-mediated floral dip method. Based on the qRT-PCR detection, successful transformed Arabidopsis individuals were selected from the progenies. The stearic acid and oleic acid content in the seeds of transgenic T3 Arabidopsis seeds and Col-0 were detected and function of SiSAD was concluded. 【Result】 Total coding region sequence of SiSAD was cloned and the sequence was the same as the reference genome. It consisted of 1 152 nucleotides encoding a protein of 383 amino acids with a calculated molecular mass of 43 kD and a predicted pI of 6.18. We found that SiSAD gene contained one conserved function domain, which had been identified as a signature motif within the fatty acid desaturase family members. The similarity of SiSAD proteins from different species was quite high, indicating that SiSAD in different plant might had conserved function. The phylogenetic tree composed of SAD proteins showed that SiSAD, InSAD and OeSAD had been grouped together, suggested a close relationship of SiSAD protein among sesame, O. europaea var. sylvestris and Ipomoea nil. In contrast, SiSAD had a far relationship to AtSAD, CsSAD and RcSAD. qRT-PCR results showed that SiSAD is organ-specific expressed and had a highest expression level in seeds. We successfully constructed the overexpression vector of SiSAD and introduced the vector into Arabidopsis by Agrobacterium-mediated transformation. qRT-PCR was used to test the transcription of SiSAD in transgenic Arabidopsis plants. Compared with the Arabidopsis wild type Col-0, stearic acid content of 3 transgenic lines with overexpressed SiSAD gene was decreased by 3.0%, 4.8% and 6.1%, respectively. Which oleic acid content in these lines was increased by 2.8%, 4.3% and 7.8% (4.97% in average). 【Conclusion】 In this study, the total coding region sequence of SiSAD was cloned and function of SiSAD was characterized. SiSAD might plays important roles in improving oleic acid content, which could be used in the genetic improvement of oleic acid content in sesame seeds.

    TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY
    Spatial-Temporal Distribution Characteristic and Interaction Between Agronomic Traits of Winter Wheat and Precipitation of Growth Period in Huang-Huai Dryland
    LI ShiJing, XU Ping, ZHANG ZhengBin, WEI YunZong
    Scientia Agricultura Sinica. 2019, 52(10):  1686-1697.  doi:10.3864/j.issn.0578-1752.2019.10.003
    Abstract ( 472 )   HTML ( 36 )   PDF (3271KB) ( 506 )   Save
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    【Objective】This article was to study the spatial-temporal distribution and interaction between agronomic traits of winter wheat and precipitation of growth period, and to provide a theoretical basis for variety improvement of winter wheat in Huang-Huai dryland under climate change.【Method】The data of agronomic traits and precipitation of the national regional trials of Huang-Huai dryland from 2010 to 2017 were used to analyze the spatial-temporal distribution and interaction by geographic methods and statistical methods.【Result】In terms of spatial distribution, the actual yield per unit area and 1000-kernel weight of winter wheat showed an increasing trend from west barren dryland to east fertile dryland. The plant height showed higher in the west barren dryland and lower in the middle and east fertile dryland. The total precipitation of different growth stages in the north of central and eastern Huang-Huai dryland was generally low, the south of central and eastern Huang-Huai dryland relatively high. In terms of time change, the total precipitation of germination to maturity period in the central and western dryland of Henan, Shanxi and Shaanxi showed a significant increasing trend. The total precipitation of germination to heading period was significantly positively correlated with actual yield, plant height, and number of effective ears. The results of path analysis showed that the plant height and the number of effective ears determined 53.2% of the actual yield variation in Huang-Huai fertile dryland, and the plant height and 1000-kernel weight determined 67% of the actual yield variation in Huang-Huai barren dryland. 【Conclusion】 It was suggested that winter wheat breeding in Huang-Huai fertile dryland should increase plant height appropriately, improve the ability of efficient use of limited precipitation before flowering and increase ear development. Huang-Huai barren dryland breeding should stabilize plant height and improve the efficiency of transporting dry matter after flowering and harvest index.

    TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY
    Salinity Inversion of Severe Saline Soil in the Yellow River Estuary Based on UAV Multi-Spectra
    WANG DanYang,CHEN HongYan,WANG GuiFeng,CONG JinQiao,WANG XiangFeng,WEI XueWen
    Scientia Agricultura Sinica. 2019, 52(10):  1698-1709.  doi:10.3864/j.issn.0578-1752.2019.10.004
    Abstract ( 433 )   HTML ( 32 )   PDF (5470KB) ( 362 )   Save
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    【Objective】The purpose of this paper was to improve the extraction accuracy of soil salinity information based on remote sensing and understand accurately the degree and distribution of soil salinization. 【Method】Firstly, the severe and concentrated saline soil area of Huanghekou town, Kenli district, was selected as the experimental area, and the unmanned aerial vehicle (UAV) equipped with Sequoia multispectral camera was adopted to acquire the near earth remote sensing image from April 26th to 28th, 2018, then the image preprocessing, including image splicing, radiation correction, orthorectification and geometric correction, was performed. Secondly, the sensitive bands of soil salinity were screened by correlation analysis and grey correlation analysis, respectively, and the spectral parameters were constructed and screened. Thirdly, the soil salinity quantitative analysis models were built by multivariate linear regression (MLR), support vector machine (SVM) and partial least square (PLS) method, then the models’ accuracy was evaluated and the best one was selected. Finally, the best model was applied to the inversion and analysis of soil salinity distribution in the experimental area, and the inversion accuracy was compared with the interpolation result by inverse distance weighting (IDW) method. 【Result】The results showed that the accuracy and significance of the estimation model based on gray correlation analysis were improved by compared with the correlation analysis; Compared the three modeling methods, the prediction ability of the SVM was the best, followed by the PLS, the MLR models’ precision was the lowest, with the calibration R 2 and RMSE of 0.820 and 3.626, the validation R 2, RMSE and RPD of 0.773, 4.960 and 2.200, and the SVM model of soil salinity based on screened variables by grey correlation analysis was selected the best one; Based on the best model, the soil salinity content in this region was between 0.323 and 21.210 g·kg -1 with the average of 6.871 g·kg -1 and the severe salinity accounted for 58.094%, which was consistent with the result of the field investigation; The 80% of the error between the inversion result and the interpolation result by the IDW method was controlled within 20% of the sample salt content average, which showed that the two kind of result were similar. 【Conclusion】It could be concluded that the accurate extraction of severe soil salinity information could be achieved on the UAV multi-spectra.

    PLANT PROTECTION
    Disease Resistance of Rice stripe virus NS3-Transgenic Nicotiana benthamiana
    WU GenTu, CHEN GuangXiang, ZHANG JiaYuan, HU Qiao, MA MingGe, DOU YanXia, LI MingJun, QING Ling
    Scientia Agricultura Sinica. 2019, 52(10):  1710-1720.  doi:10.3864/j.issn.0578-1752.2019.10.005
    Abstract ( 362 )   HTML ( 13 )   PDF (2613KB) ( 559 )   Save
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    【Objective】The protein encoded by NS3 is a suppressor of RNA silencing of Rice stripe virus (RSV). In previous study, it was found that NS3 expression enhanced the resistance of Nicotiana benthamiana to RSV using transgenic technology. In order to reveal the detailed function of NS3 in host plants, the resistance of NS3-transgenic N. benthamiana to other tobacco diseases will be analyzed in this study.【Method】Wild-type and NS3-transgenic N. benthamiana were used to study the infection of Potato virus X (PVX), Ralstonia solanacearum, and Phytophthora parasitica var. nicotianae. PVX infectious clone was inoculated by agro-infiltration, viral symptoms were observed. The total RNA of infected leaves was extracted, and viral relative accumulation was detected by RT-qPCR. The method of filling root was used to inoculate R. solanacearum and P. parasitica var. nicotianae, respectively, disease symptoms were observed, and the incidence and disease index were analyzed.【Result】The main symptoms of PVX in N. benthamiana leaves were mosaic and chlorosis, and the NS3-transgenic N. benthamiana plants had the same PVX symptoms as those of wild-type plants. At 10 days past inoculation (dpi), the results of RT-qPCR showed that NS3 expression inhibited the accumulation of PVX in N. benthamiana, the relative accumulation of PVX in NS3-6 line and NS3-9 line was 68.17% and 81.01% of that of wild-type N. benthamiana, respectively. After the infection of R. solanacearum, the symptoms both in wild-type and NS3-transgenic N. benthamiana plants were wilting and damping-off. In the early stage of disease, the expression of NS3 was beneficial to the infection of R. solanacearum to a certain extent, which showed that it was more sensitivity to bacterial wilt. At 14 dpi, the incidence and disease index of bacterial wilt of wild-type N. benthamiana were 100.00% and 78.67, while the incidence of NS3-6, NS3-9 line was 95.00%, 98.33%, and the disease index was 70.00, 73.00, respectively. After 14 dpi, the incidence and disease index increased gradually, while the disease index of NS3-transgenic lines was lower than that of wild-type plants. The black-brown necrotic patches at the base of stem were observed both in wild-type and transgenic plants after P. parasitica var. nicotianae infection, and the expression of NS3 did not affect the symptoms of N. benthamiana. At the early stage of P. parasitica var. nicotianae infection, the incidence of black shank disease in NS3-6 was higher than that of wild-type N. benthamiana, however, during the whole process of black shank disease, the disease index of NS3-transgenic lines was lower than that of wild-type N. benthamiana. At 12 dpi, the incidence and disease index of black shank disease in wild-type N. benthamiana were 96.67% and 77.50, while the incidence of NS3-6, NS3-9 line was 90.00%, 86.67%, and the disease index was 64.17, 62.08, respectively.【Conclusion】The observation of pathogen infection process showed that the expression of NS3 affected the infection and severity of tobacco diseases on N. benthamiana to a certain extent, and the effects on different pathogens were also different.

    The Phototaxis Behavior of Thrips tabaci and Trapping Effect of Different Wavelength Sticky Cards in the Field
    MI Na,Zhang QiKai,WANG HaiHong,WU ShengYong,LEI ZhongRen
    Scientia Agricultura Sinica. 2019, 52(10):  1721-1732.  doi:10.3864/j.issn.0578-1752.2019.10.006
    Abstract ( 487 )   HTML ( 14 )   PDF (562KB) ( 397 )   Save
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    【Objective】 The objective of this study is to explore the optimum light wavelength, light intensity and related factors, such as sex, daily rhythm, starvation time, temperature and relative humidity of Thrips tabaci through behavioral responses study under the different conditions of laboratory, greenhouse and field, and to provide a theoretical support for improving the control techniques and products of T. tabaci, such as color sticky cards and light traps. 【Method】 Firstly, the behavioral responses of T. tabaci to 10 different wavelengths of monochromatic light were conducted by using monochromator testing device with high resolution, wide spectrum measurement range and high stability under laboratory condition. Monochromatic light with high response rate was screened and the initial light intensity was attenuated by neutral density filter to explore the effect of light intensity on the behavioral responses of T. tabaci. Secondly, the effects of sex, daily rhythm, starvation time, temperature and relative humidity on phototaxis of T. tabaci were also examined by using the rate of phototaxis as statistical index. Based on laboratory experiments, using the relationship between Dan Bruton’s virtual wavelength and RGB values, the blue and yellow sticky cards of the corresponding wavelengths were printed and the plates were glued. The tendency of T. tabaci to the self-made sticky cards of different wavelengths and sticky cards produced by different manufacturers was evaluated in the greenhouse and in the open field.【Result】The results of laboratory experiment showed that phototaxis behavioral response rate was the highest on blue light at 450 nm, and the rate of photaxis was as high as 75.34%, followed by the yellow light at 562 nm and the blue-purple light at 430 nm, the rate of photaxis was 73.61% and 64.03%, respectively. Under the stimulation of 430, 450 and 562 nm monochromatic light, the phototaxis rate of female T. tabaci was higher than that of male. The light intensity attenuation test of the three monochromatic light showed that the tendency of T. tabaci increased with light intensity. At 8: 30-10: 00 am, the T. tabaci was most sensitive to monochromatic light at 430, 450, and 562 nm. After 4 hours of starvation, the phototaxis rate of T. tabaci was the strongest, and then decreased with the prolongation of starvation time. The phototaxis rate of T. tabaci to three monochromatic light was significantly higher than that of the control at 25-30℃. At 15℃, T. tabaci was not sensitive to monochromatic light stimulation. Under the relative humidity of 45%-60%, the phototaxis rate of T. tabaci was significantly stronger than that of the control at 430, 450 and 562 nm. However, there was no significant difference with the control under the relative humidity of 30% and 90%. The trapping effect on T. tabaci was evaluated by using different wavelength sticky cards and different manufacturers in the greenhouse and field, and the results showed that the blue self-made sticky cards and the No.2 sticky cards with reflection wavelength of 440-470 nm had the best effect. The results of this test were in agreement with the optimum wavelength of laboratory screening. 【Conclusion】 Sex, daily rhythm, starvation, temperature and relative humidity all have certain influence on phototaxis of T. tabaci. Comprehensive analysis on laboratory, greenhouse and field revealed that T. tabaci has obvious tendency to monochromatic light and sticky cards at 450 nm. The blue trap sticky card of about 450 nm can be used to monitor and control T. tabaci.

    SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT
    Effects of Soil Inorganic Nitrogen and Nitrogen Absorbing by Maize Under the Reduced Application of Coated Urea at Different Proportions
    FENG XiaoJie,ZHAN XiuMei,WANG XueXin,CHEN Kun,PENG Jing,HAN XiaoRi
    Scientia Agricultura Sinica. 2019, 52(10):  1733-1745.  doi:10.3864/j.issn.0578-1752.2019.10.007
    Abstract ( 423 )   HTML ( 22 )   PDF (482KB) ( 319 )   Save
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    【Objective】 By studying the effects of nitrogen releasing and nitrogen absorbing by maize under the application of different ratios with coated urea and ordinary urea, this paper aimed to screen the optimal ratio, which was beneficial to the outputs of spring maize in the northeast China and nitrogen utilization efficiency, and to provide the basis for the generalizing of controlled release nitrogen fertilizer on maize.【Method】Field experiments were set in Shenyang and Haicheng of Liaoning province in 2017, and crop strains were Dongdan6531 and Tieyan358, respectively. The experiment fertilizers were ordinary and coated urea. The treatments in both set points included blank control (CK0), ordinary urea nitrogen control (CK) and decreased urea N control treatments (CK1), decreased coated urea N control (T0)compared with (CK)treatments; three different ratios urea between ordinary and coated were arranged in Shenyang (T1, T2 and T3) and two in Haicheng (T1 and T2). The ratios of T1, T2 and T3 were 8:2, 6:4 and 4:6, respectively; the ordinary urea control rate was 244 kg·hm -2 and decreased coated urea N control was 220 kg·hm -2 in Shenyang and that were 217 kg·hm -2 and 195 kg·hm -2 in Haicheng, respectively. Soil and plant samples were collected according to the maize growing season, respectively. Determination of the content of soil inorganic nitrogen and different plant parts nutrient, and the biological yield of different treatments were also measured.【Result】The treatments of coated urea plus the ordinary increased the maize yield significantly (P<0.05), and with the ratio increasing, the yield first rise and then drop. The yield of T2 was the highest (10 250 kg·hm -2), and CK1 was the lowest (9 307 kg·hm -2). The yields of equal N inputting treatments were in the order as T2>T3>T1>T0>CK1, and the grain yield increased 3.89%-25.76% compare to CK1, but there was no significant difference between T2 and CK. The soil inorganic N content was increased at the early maize growth stage applying with either type urea, and the soil N content was rich at the late maize growth stage applying with coated urea. Under the same N input treatments, the N use efficiency (NUE) and agronomic efficiency of N fertilizer (AEN) applied first rise and then drop with the ratio increasing, and T2 was the highest, CK1 was the lowest, the results in different place was the same.【Conclusion】Coated urea plus ordinary urea performed better than other treatments on yield, AEN and NUE, and T2 (i.e. 6:4 of the coated and ordinary urea) was the best. According to the characteristics of coated urea and ordinary urea, we fitted a curve for those results, and made it to know that 62% coated urea plus 38% ordinary urea input could get the best NUE and maize yield in South Central Liaoning, which could increase soil N content at the late of crop growth stage by using coated urea and ordinary urea to their advantages fully, gaining yield and economic benefits.

    SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT
    Effects of Nitrogen Fertilizer on Crop Residue Decomposition and Nutrient Release Under Lab Incubation and Field Conditions
    ZHANG XueLin, ZHOU YaNan, LI XiaoLi, HOU XiaoPan, AN TingTing, WANG Qun
    Scientia Agricultura Sinica. 2019, 52(10):  1746-1760.  doi:10.3864/j.issn.0578-1752.2019.10.008
    Abstract ( 473 )   HTML ( 31 )   PDF (500KB) ( 440 )   Save
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    【Objective】 The study was carried out to investigate factors affecting the decomposition and nutrient release of wheat and maize residue under indoor and field conditions, so as to provide a theoretical basis for the rational return of crop residue and its suitable nutrient management practices. 【Method】 We conducted indoor incubation experiment with nylon bag and field experiment to study residue decomposition characteristics of wheat and maize under various nitrogen (N) fertilizer dosages (0, CK; 180 kg N·hm -1, N180; 360 kg N·hm -2, N360). In indoor environment, we focused on the effects of N dosage and soil types (Shajiang black soil: ST, Fluvo-aquic soil: FT), while in field condition, we emphasized on the effects of N dosages and burying depth (surface and 20 cm depth treatment) of the residue. 【Result】 Laboratory studies found that both residue types and soil types significantly affected residue decay constant, C, N, and P release. With the increasing of N application rate, the decay constant of wheat residue increased in both soil types, while the maize residue decreased. The N releases of maize and wheat residue decreased (the wheat residue increased in FT soil). The decay constant of wheat residue of the FT soil and the release of C, N, and P were significantly higher than those of the ST soil, while the soil types had little effect on the decomposition of maize residue. Under the lab incubation condition (180d), the average C releases of wheat residue were 370 g·kg -1, N was 4 g·kg -1, and P was 3.6 g·kg -1; maize residue C release was 560 g·kg -1, N was 11 g·kg -1, and P was 3.3 g·kg -1. Under field condition, the depth of residue returning significantly affected the decay constants of wheat and maize residue and the release of C, N and P. The decay constant and nutrient releases of residues treated with 20 cm were significantly higher than that of surface treatment. For surface treatment, the decay constant and C release of wheat residue declined gradually with the increase of N fertilizer application rate, but the maize residue increased. For 20 cm treatment, the decay constant of wheat residue and the release of C, N, and P increased with the amount of N fertilizer, while maize residue showed a decreasing trend. Under field condition, surface wheat residue biomass could decompose 40% after a maize growing season (June - October 2015), releasing 150 g C·kg -1, 2 g N·kg -1and 3.5 g P·kg -1; burying underground to 20 cm could decompose 80%, releasing 360 g C·kg -1, 4 g N·kg -1, and 3.8 g P·kg -1. Maize residues biomass could only decompose 40% after a wheat growth season (October 2015-June 2016) when the residues being returned to the surface, releasing 210 g C·kg -1, 5 g N·kg -1, and 2 g P·kg -1, but the 20 cm treatment could decompose 60%, releasing 360 g C·kg -1, 6 g N·kg -1, and 2.5 g P·kg -1. Principal component analysis showed that the decay constant of wheat residue under indoor conditions was significantly positively correlated with soil inorganic N, urease and straw N content, and negatively correlated with soil sucrase and straw C/N ratio, while maize residue decay constant was negatively correlated with soil inorganic N. Under field conditions, the decay constant of wheat residue was negatively correlated with soil urease, soil invertase, residue C content, N content and residue C/N ratio, while maize residue decay constant was negatively correlated with soil inorganic N content, soil urease, invertase and residue C/N ratio, and positively correlated with residue N and P content.【Conclusion】Both indoor and field experiment showed that the decay constants and nutrient release characteristics of wheat and maize residue were different. The application of N fertilizer promoted the decomposition of wheat residue but had little effect on the decomposition of maize residue. The soil types (ST and FT) significantly affected the decomposition of wheat residue, but the effects on maize residue decomposition were small. Returning crop residue to the soil could significantly promote the decomposition of wheat and maize residue and its nutrient release. In production, the crop residue should be returned to the soil, and appropriate N dosage should be adopted to soil types and residue types to promote the decomposition of straw.

    HORTICULTURE
    Responses of Plant Nutrient and Photosynthesis in Greenhouse Tomato to Water-Fertilizer Coupling and Their Relationship with Yield
    WANG HuBing, CAO HongXia, HAO ShuXue, PAN XiaoYan
    Scientia Agricultura Sinica. 2019, 52(10):  1761-1771.  doi:10.3864/j.issn.0578-1752.2019.10.009
    Abstract ( 343 )   HTML ( 11 )   PDF (390KB) ( 348 )   Save
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    【Objective】The objectives of the study were to explore the coupling effects of water and fertilizer on tomato plant nutrient absorption, photosynthetic parameters and their relationships, so as to provide a theoretical basis for water and fertilizer management of greenhouse tomato in Northwest China.【Method】The experiment was conducted in a solar greenhouse, and water volumes based on moisture evaporation were set as 1.00E (W1), 0.75E (W2) and 0.50E (W3). Fertilizer treatments of N-P2O5-K2O (F) included 320-160-320 kg?hm -2 (high fertilizer, F1), 240-120-240 kg?hm -2 (middle fertilizer, F2) and 160-80-160 kg?hm -2 (low fertilizer, F3), Besides, the local irrigation and fertilization was set as control (CK).【Result】The results showed that irrigation and fertilization had a significant effect on leaf area index (LAI) and chlorophyll content, as well as LAI and chlorophyll content increased with the increasing of irrigation and fertilization. LAI reached the maximum value at the ripening stage, while chlorophyll content firstly increased then decreased with plant growth, and reached the maximum value at the fruit expansion stage. The contents of N, P and K in leaves showed the N>K>P trend, and the content was 22.83-47.20, 4.45-7.08 and 22.00-34.92 g?kg -1, respectively. The increasing of irrigation and fertilization was beneficial to the increase of leaf nutrient content, plant nutrient accumulation and nutrient transfer to fruit, which reached the maximum value under W1F1 treatment except for the content of N at 51d and P at 89d in leaves and P accumulation in plant. Irrigation and fertilization had a significant effect on net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr). Pn, Gs and Tr increased with the increasing of irrigation amount and fertilizer amount. Among different fertilizer and water treatments, W1F1 treatment had the highest Pn, while CK had the highest Tr except for 90d. Pn reduced significantly under water stress during tomato ripening period. The Pn, Gs and Tr value did not enhance significantly when the irrigation continued to increase at W1 level. The contents of N, P and K in leaves were positively correlated with chlorophyll content and Pn at different growth stages. In addition, plant and fruit nutrient accumulation amount of tomato showed a significant positive correlation with net photosynthetic and yield. 【Conclusion】In conclusion, the W1F1 treatment (irrigation amount of 1.0E and fertilizer of N-P2O5-K2O 320-160-320 kg?hm -2) was considered as the optimal fertilizer and water treatment through the comprehensive consideration of leaf area index, chlorophyll content, photosynthetic parameters, plant nutrient accumulation and yield of tomato.

    Screening, Cloning and Functional Research of the Rare Allelic Variation of Caffeine Synthase Gene (TCS1g) in Tea Plants
    LIU YuFei,JIN JiQiang,YAO MingZhe,CHEN Liang
    Scientia Agricultura Sinica. 2019, 52(10):  1772-1783.  doi:10.3864/j.issn.0578-1752.2019.10.010
    Abstract ( 421 )   HTML ( 12 )   PDF (5997KB) ( 318 )   Save
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    【Objective】 Tea caffeine synthase 1 (TCS1), a key enzyme in the caffeine biosynthesis pathway, shows a wide range of allelic variation within Camellia sect. Thea germplasm. Discovery of the specific alleles of TCS1 as the genetic basis of natural variation in caffeine levels will increase the understanding of the mechanism of caffeine synthesis and accumulation, and provide new genetic resources for improving caffeine content in tea plant. 【Method】 An unique PCR primer set, namely TCS1P InDel F/R, was used to detect TCS1 alleles in 673 accessions of tea germplasm. The primer set (TCS1cDNAF/R) was used to clone the full-length cDNA sequence of novel allele, whose function was subsequently validated by bioinformatics quantitative real-time PCR (qRT-PCR) and prokaryotic expression analysis. 【Result】 The novel rare allele, TCS1g, was identified in the several germplasm of C. taliensis. The TCS1g sequence was obtained by using the accession ‘LL17’, which contained both TCS1a and TCS1g. The CDS of TCS1g was 1098 bp, encoding 365 amino acids with a calculated molecular weight of 40.9 kD and a theoretical isoelectric point 5.1. The sequence similarities between TCS1g and TCS1a, TCS1b, TCS1c, TCS1d, TCS1e, TCS1f ranged from 94.1% to 99.2%. The TCS1g showed a high level (>96%) of amino acid sequence identity with the alleles (TCS1b and TCS1c) which had only theobromine synthase (TS) activity, while it was slightly lower for other alleles (TCS1a, TCS1d, TCS1e and TCS1f ) having both TS and caffeine synthase (CS) activity. The amino acid residue in position 221, located at the active center motif of TCS1, was histidine (His) in the TCS1g, as well as TCS1b and TCS1c, however it was arginine (Arg) for the others. The mutation (His to Arg) would change the isoelectric point and hydrophilicity from 5.05 to 5.06, and from -0.119 to -0.123, respectively. Meanwhile, the 5' upstream regulatory region of TCS1g, TCS1b and TCS1c was 15 bp longer than that of TCS1a, TCS1d, TCS1e and TCS1f. The results of prokaryotic expression analysis indicated that TCS1g had only TS activity (44.3 pkat/mg), and qRT-PCR analysis showed the TCS1g was expressed in the ‘LL17’. The contents of caffeine and theobromine in the ‘LL17’ were 40.3 mg·g -1and 5.4 mg·g -1, respectively. 【Conclusion】 A novel rare allele of TCS1 (TCS1g) was cloned, and the expression was detected in the ‘LL17’. TCS1g had TS activity, but no CS activity, which might be caused by the change of amino acid residue in position 221.

    FOOD SCIENCE AND ENGINEERING
    Classification Criteria and Storage Characteristics of Actinidia Arguta Fruits with Different Maturities
    GAO Xue,ZHANG Yin,XIN Guang,ZHANG Bo,MU JingJing,LI YiMeng,LIU ChangJiang,SUN XiaoRong,LI Bin
    Scientia Agricultura Sinica. 2019, 52(10):  1784-1796.  doi:10.3864/j.issn.0578-1752.2019.10.011
    Abstract ( 658 )   HTML ( 21 )   PDF (520KB) ( 302 )   Save
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    【Objective】The aim of this study was to establish the classification criteria of different maturities to determine the optimal harvest time of Actinidia arguta fruits. Furthermore, the fruit qualities of 70%, 80% and 90% maturity levels were investigated, in order to provide theoretical guidance for the storage characteristic studies of Actinidia arguta fruits.【Method】Different indicators, including hardness, seed color transformation index, the contents of soluble solids, titratable acid, starchand tannin, were studied and analyzed by correlational and hierarchy analysis. Consequently, the comprehensive scoring model was established for the classification criteria with different fruit maturities. Then the physico-chemical changes of fruits at different harvesting stages were determined.【Result】During blossom period, the comprehensive scores of fruits were ≤0.3209 (at 76 and 78 d), 0.3209-0.4562 (at 80 and 82 d), 0.4562-0.6440 (at 84 and 92 d), ≥0.6440 (at 94 and 96 d), the maturity levels were 70%, 80%, 90% and 100%, respectively. Compared with 70% maturity fruits, the decay index of the 80% maturity fruits was significantly lower and the hardness was significantly higher. The contents of tannin and soluble solids of 80% and 90% maturity fruits were similar, and the other indicators could reach optimum ripeness during storage, but the latter had shorter storage life. The70% maturity fruits, which soluble solid content was the lowest, which couldn’t undergo after-ripening process during storage.【Conclusion】The comprehensive scores of Actinidia arguta fruit were ≥0.6440, 0.4562-0.6440, 0.3209-0.4562, ≤0.3209, and the corresponding maturities were 100%, 90%, 80% and 70%, respectively. Fruits of 80% maturity level were more suitable for long-term storage, staggered season and long-distance selling. Fruits of 90% maturity level were preferred to sale and process locally.

    ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT
    Development of Models of Methane Emissions from Growing Sheep
    ZHOU Yan, DONG LiFeng, DENG KaiDong, XU GuiShan, DIAO QiYu
    Scientia Agricultura Sinica. 2019, 52(10):  1797-1806.  doi:10.3864/j.issn.0578-1752.2019.10.012
    Abstract ( 323 )   HTML ( 20 )   PDF (382KB) ( 309 )   Save
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    【Objective】 This study was aimed to investigate the methane (CH4) emission and develop CH4 prediction models of growing sheep. 【Method】 The average daily weight gain of the treatment of NFC/NDF = 0.78, 1.03 and 2.17 was used as the reference for the restricting level of feed for the other three treatments, respectively, and the digestibility of nutrients and methane production of meat sheep were measured on this basis. Furthermore, the regression relationships were established between CH4 production and dietary nutrient content, nutrient intake, digestible nutrients intake, and apparent digestibility of nutrients. 【Result】When the sheep grew from 25 to 35 kg BW, the most accurate single-variable and multivariate regression model were shown below: CH4(L/d)= -26.58 × NFC/NDF + 92.70(R 2 = 0.772, P <0.001); CH4 (L/d) = 2.71 × NDFD - 2.45 × DMD - 0.97 × CPD + 124.46 (R 2 = 0.846, P = 0.001). When the sheep grew from 48 to 55 kg BW, the most accurate single-variable and multivariate regression model were shown below: CH4 (L/d) = -57.00 × GE (MJ·kg -1) + 1076.01 (R 2 = 0.581, P = 0.002); CH4/BW 0.75(L·kg -1) = - 0.01 × NDFI (g·d -1) - 0.13 × CPI (g·d -1) + 0.02 × DMI (g·d -1) + 0.84 (R 2 = 0.652, P = 0.019). The most accurate single-variable and multivariate regression model in the overall growing period of sheep were shown below: CH4(L/d)= -26.94 × NFC/NDF + 90.71(R 2= 0.655, P <0.001); CH4/BW 0.75(L·kg -1) = 0.005 × DNDFI (g·d -1) + 0.011 × DDMI (g·d -1) - 0.097 × DCPI (g·d -1) - 4.78 (R 2 = 0.722, P <0.001). 【Conclusion】 The regression relationships were established for the respective growth periods (25-35 kg and 48-55 kg BW) and the overall growth period (25-55 kg BW). The studies showed that the optimal methane prediction factors for meat sheep at different weight were various, and methane production was greatly affected by dietary NFC/NDF, which could be used as a theoretical basis for the evaluation of methane production under the breeding model in China and a reference for the diets of meat sheep.

    Polymorphisms of ADIPOQ Gene and Their Association with Growth and Carcass Traits in Sheep
    AN QingMing,ZHOU HuiTong,WU ZhenYang,LUO YuZhu,Jon G. Hickford
    Scientia Agricultura Sinica. 2019, 52(10):  1807-1817.  doi:10.3864/j.issn.0578-1752.2019.10.013
    Abstract ( 304 )   HTML ( 16 )   PDF (548KB) ( 371 )   Save
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    【Objective】In this study, polymorphisms and linkage relationship of ovine ADIPOQ (adiponectin) gene were investigated and their effects on some growth and carcass traits were estimated, so as to enrich the molecular genetic data for sheep. 【Method】Mutations in Exon-1 and Exon-2 of ADIPOQ gene were detected by PCR-SSCP in 8 commodity sheep populations, and the relationship between mutations in growth and carcass traits in New Zealand (NZ) Romney lambs was investigated using General Linear Models (GLMs). 【Result】In total, thirteen SNPs were detected in Exon-1 and Exon-2 regions of ovine ADIPOQ gene, and the nucleotide substitution c.46T/C in Exon-2 resulted in amino acid change (p.Tyr16His). Allele A1 and B1 were the dominant allele in Exon-1, Allele A2 and D2 were the dominant allele in Exon-2, and there were difference of allele frequencies between these two regions. The majority population was moderately polymorphic in all regions (PIC<0.5), except Texel, Perendale and Dorset Down was low polymorphic in Exon-2 region (PIC<0.25), and there was a high linkage relationship of these mutation and tend to shared genetic linkages (D’=0.952, r 2=0.365). The association analysis showed that the mutations in Exon-1 region of ovine ADIPOQ gene had different effects on growth traits of male and female lambs. In male lambs, individuals with possessing allele A1 had lower tailing weight, weaning weight and pre-weaning growth rate than those no-possessing (P<0.05), but no associations were detected in female lambs (P>0.05). In female lambs, individuals with possessing allele B1 had higher tailing weight than those no-possessing (P<0.05), however, no associations were detected in male lambs (P>0.05). And individuals with possessing B1B1 had higher tailing weight and weaning weight in male lambs. The carcass traits association analysis results showed that individuals with possessing allele A1 had lower hot-carcass weight, loin yield, leg yield and total yield than those no-possessing (P<0.05), and individuals with possessing allele B1 had higher leg yield, proportion of led yield and lower proportion shoulder yield than those no-possessing (P<0.05), individuals with possessing B1B1 had higher hot carcass weight, loin yield, leg yield and total yield (P<0.05). 【Conclusion】Exon-1 and Exon-2 of ovine ADIPOQ gene had abundant polymorphisms, and SNP c.46T/C was non-synonymous. The mutations of Exon-1 of ovine ADIPOQ gene might affect some growth traits and carcass traits, and selecting sheep with allele B1 and genotype B1B1, or eliminating ones with allele A1 and A1A1 could improve some growth traits and carcass traits of Romney sheep.

    Silencing and Overexpressing SMAD Family Member 1 (SMAD1) Gene and Its Effect on Myogenesis in Primary Myoblast of Qinchuan Cattle (Bos taurus)
    NING Yue,MI Xue,CHEN XingYi,SHAO JianHang,ZAN LinSen
    Scientia Agricultura Sinica. 2019, 52(10):  1818-1829.  doi:10.3864/j.issn.0578-1752.2019.10.014
    Abstract ( 466 )   HTML ( 17 )   PDF (5157KB) ( 207 )   Save
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    【Objective】The aims of the present study were to investigate molecular function of SMAD1 gene in the bovine myoblast cell differentiation and to explore its role in the growth and development of Qinchuan cattle for beef production.【Method】SMAD1 gene was silenced and overexpressed through RNA interference and adenovirus recombinant over expression vector containing SMAD1. The negative control siRNA-NC and RNA interference specific targeted SMAD1 gene (siSMAD1) were designed and synthesized against the bovine SMAD1 mRNA sequence (CDS), which was obtained by RT-PCR using cDNA of Qinchuan cattle myoblast as template, and then, which was inserted into a shuttle vector pDC316-mCMV-EGFP to construct the over expression of adenovirus shuttle vector pDC316-mCMV-EGFP-bSMAD1. Adenovirus genome plasmid and adenovirus shuttle vectors were cotransfected into HEK293 cell line to pack and obtain recombinant adenovirus. Adenovirus containing target gene was named as AD-bSMAD1, while pDC316-EGFP was used as a reference vector and was considered as control group "AD-NC". Their titers were tested by using LaSRT method. Bovine myoblast were transfected with siSMAD1 and AD-bSMAD1, the mRNA level of SMAD1 gene and myogenesis-related genes, such as MyoD, Myf5 and MyoG, were detected by real-time quantitative PCR, and the impact on myotube formation was observed. 【Result】 The mRNA level of SMAD1 gene transfected with siRNA was reduced 75.4% (induced differentiation for 1 day, P<0.01), 66.7% (induced differentiation for 3 days, P<0.01), 60.0% (induced differentiation for 6 days, P<0.01), 54.7% (induced differentiation for 9 days, P<0.01), respectively, compared with the siRNA-NC. The optimum titer of AD-bSMAD1 infectious was found at 1×10 10pfu/mL. The expression levels of SMAD1 were rapidly increased 2.10 (induced differentiation for 1 day), 3.19 (induced differentiation for 3 days), 105.3 (induced differentiation for 6 days, P<0.01) and 144 (induced differentiation for 9 days, P<0.01) times of the control group after infected by AD-bSMAD1, respectively. In addition, both myotube formation and qRT-PCR results proved that SMAD1 gene promoted myoblasts differentiation and myotube formation, as well as the mRNA expression level of MyoD, Myf5, and MyoG. 【Conclusion】 We could conclude from the present study that SMAD1 gene performed its function in the myoblast differentiation and myotube formation. Based upon these findings, SMAD1 gene could be used as potential marker for the breed improvement of Qinchuan cattle through marker assisted selection for beef production.

    Expression, Purification and Localization Analysis of Polar Tube Protein 2 (NbPTP2) from Nosema bombycis
    YI Min,LÜ Qing,LIU KeKe,WANG LiJun,WU YuJiao,ZHOU ZeYang,LONG MengXian
    Scientia Agricultura Sinica. 2019, 52(10):  1830-1838.  doi:10.3864/j.issn.0578-1752.2019.10.015
    Abstract ( 364 )   HTML ( 13 )   PDF (1106KB) ( 476 )   Save
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    【Objective】Microsporidia are eukaryotic intracellular obligate parasites that infect almost all organisms, including human. As a special infection organ, the polar tube is mainly composed of polar tube proteins. The polar tube protein plays an important role in microsporidia invasion host and maintaining the structure of polar tube. The objective of this study is to clone and express Nosema bombycis polar tube protein 2 (NbPTP2), analyze its localization characteristics in mature spores, and to lay a foundation for further study the function of polar tube proteins.【Method】NbPTP2 was amplified from N. bombycis genome. The amino acid composition, theoretical molecular weight and predicted isoelectric point of NbPTP2 were analyzed by Expasy online software. SignalP 4.1 and TMHMM Server V. 2.0 were used to predict the signal peptide and transmembrane domain of NbPTP2. The phosphorylation site of NbPTP2 was analyzed by NetPhos 3.1 Server. The phylogenetic tree of NbPTP2 from different microsporidia species was constructed by MEGA 7.0. NbPTP2 was amplified from N. bombycis genome, then ligated with prokaryotic expression vector pET32a (+). The correctly sequenced recombinant plasmid was transformed into Escherichia coli Rosetta, and protein expression was heterologous induced by IPTG. The polyclonal antibody of NbPTP2 was prepared by immunizing New Zealand rabbits with the fusion protein by affinity chromatography purification. The expression of NbPTP2 in mature spores was detected by Western blot. Indirect immunofluorescence assay (IFA) was used to analyze the localization characteristics of NbPTP2 in mature spores of microsporidia. 【Result】 The NbPTP2 with a length of 834 bp was successfully cloned. The protein encodes 278 amino acid residues with a theoretical molecular weight of 30.9 kD, and isoelectric point of 9.39. Moreover, it was predicted to have a N-terminal signal peptide and potential phosphoric acid sites, but no transmembrane domain. The phylogenetic tree analysis result showed that NbPTP2 from N. bombycis was closely related to NaPTP2 from N. apis and NcPTP2 from N. ceranae. Western blot result showed that NbPTP2 was expressed in mature spores of N. bombycis and its molecular weight was about 39 kD. The localization analysis result of IFA indicated that NbPTP2 could locate on the whole polar tube of N. bombycis, and it was confirmed that NbPTP2 was a polar tube protein. 【Conclusion】 The relationship between NbPTP2 and polar tube protein 2 from other microsporidia was clarified. NbPTP2 was expressed in N. bombycis and could be localized on the whole polar tube after germination. These results can provide a basis for polar tube structure analysis and polar tube protein function research.