2018 Vol. 17 No. 08 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
    Agricultural Economics and Management

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    Crop Science
    Identification and genetic analysis of multiple P chromosomes of Agropyron cristatum in the background of common wheat
    CHEN Hong-xin, HAN Hai-ming, LI Qing-feng, ZHANG Jin-peng, LU Yu-qing, YANG Xin-ming, LI Xiuquan, LIU Wei-hua, LI Li-hui
    2018, 17(08): 1697-1705.  DOI: 10.1016/S2095-3119(17)61861-6
    Abstract ( )   PDF in ScienceDirect  
    Agropyron cristatum, a wild relative of common wheat (Triticum aestivum L.), provides many desirable genetic resources for wheat improvement, such as tolerance to cold, drought, and disease.  To transfer and utilize these desirable genes, in this study, two wheat-A. cristatum derivatives II-13 and II-23 were identified and analyzed.  We found that the number of root tip cell chromosomes was 44 in both II-13 and II-23, but there were four and six P genome chromosomes in II-13 and II-23, respectively, based on genomic in situ hybridization (GISH).  The chromosome configurations of II-13 and II-23 were both 2n=22II by the meiotic analysis of pollen mother cells (PMCs) at metaphase I, indicating that there were two and three pairs of P chromosomes in II-13 and II-23, respectively.  Notably, wheat chromosome 7D was absent in derivative line II-13 while II-23 lacked chromosomes 4B and 7A based on SSR analysis combining fluorescence in situ hybridization (FISH) analysis with pAs1 and pSc119.2 as probes.  Chromosomes 2P and 7P were detected in both II-13 and II-23.  Another pair of P genome chromosomes in II-23 was determined to be 4P based on expressed-sequences tags-sequence tagged sites (EST-STS) markers specific to A. cristatum and FISH with probes pAcTRT1 and pAcpCR2.  Overall, these results suggest that II-13 was a 7P (7D) substitution line with one pair of additional 2P chromosomes and II-23 was a multiple 4P (4B), 7P (7A) substitution line with one pair of additional 2P chromosomes.  Moreover, we obtained six alien disomic addition lines and five alien disomic substitution lines by backcrossing.  These new materials will allow desirable genes from A. cristatum to be used in common wheat.
    Influence of protein characteristics and the proportion of gluten on end-use quality in Korean wheat cultivars
    Seong-Woo Cho, Chon-Sik Kang, Hyeon Seok Ko, Byung-Kee Baik, Kwang-Min Cho, Chul Soo Park
    2018, 17(08): 1706-1719.  DOI: 10.1016/S2095-3119(17)61822-7
    Abstract ( )   PDF (4989KB) ( )  

    The effects of protein characteristics and the proportion of gluten on end-use quality in 13 Korean wheat cultivars for three years were verified in this study.  Year, cultivar, and the interaction between the year and the cultivar influenced protein characteristics, the proportion of gluten except for γ- and ω-gliadin using RP-HPLC (reversed-phase high-performance liquid chromatography), and end-use quality.  Protein characteristics and the proportion of gluten in Korean wheat cultivars were between those of Australian standard white (ASW) and hard wheat (AH).  Korean wheat cultivars exhibited a higher average α+β gliadin proportion than imported wheat, a γ-gliadin proportion similar to that of dark northern spring wheat, and the same ω-gliadin proportion as AH.  They showed a bread-loaf volume intermediate between those of ASW and AH and a texture of cooked noodles similar to that of soft white wheat, but less springiness than imported wheat.  The cookie diameter of Korean wheat cultivars was similar to that of hard red winter wheat.  There was a correlation between bread-loaf volume and protein characteristics, except for the protein content in Korean wheat cultivars.  Springiness and cohesiveness of cooked noodles were not correlated with protein characteristics, while hardness was correlated with the protein content and water absorption of a mixograph.  Cookie diameter was negatively correlated with the sodium dodecyl sulfate (SDS) sedimentation volume and water absorption of a mixograph.  The end-use quality was not correlated with any proportion of gluten composition.  Principal component analysis (PCA) showed that the proportion of gluten was not related to the quality of the bread (both PCs, 81.3%), noodle (77.7%), and cookie (82.4%).  PCA explained that Keumkang is suitable for superior bread, while Uri is good for cooked noodles and cookies.

    Development of EST-PCR markers specific to the long arm of chromosome 6V of Dasypyrum villosum
    SUN Hao-jie, SONG Jing-jing, XIAO Jin, XU Tao, WEI Xing, YUAN Chun-xia, CAO Ai-zhong, XING Liping, WANG Hai-yan, WANG Xiu-e
    2018, 17(08): 1720-1726.  DOI: 10.1016/S2095-3119(17)61866-5
    Abstract ( )   PDF in ScienceDirect  
    Expressed sequence tags-derived polymerase chain reaction (EST-PCR) molecular markers specific for alien chromosomes can be used to not only monitor the introgressed alien chromatin in wheat background, but also provide the evidence of the syntenic relationship between homoeologous chromosomes.  In the present study, in order to develop high density and evenly distributed molecular markers specific for chromosome 6VL of Dasypyrum villosum, 297 primer pairs were designed based on the expressed sequence tags (EST) sequences, which were previously mapped in different bins of the long arms of wheat homoeologous 6AL, 6BL, and 6DL.  By using the Triticum aestivum, D. villosum, T. durum-D. villosum amphiploid, and T. aestivum-D. villosum alien chromosome lines involving chromosome 6V, it was found that 32 (10.77%) primers could amplify specific bands for chromosome 6V, and 31 could be allocated to chromosome arm 6VL.  These 6VL specific markers provided efficient tools for the characterization of structural variation involving the chromosome 6VL in common wheat background as well as for the selection of useful genes located on 6VL in breeding programs.
    Identification of novel soybean oil content-related genes using QTLbased collinearity analysis from the collective soybean genome
    XU Ming-yue, LIU Zhang-xiong, QIN Hong-tao, QI Hui-dong, WANG Zhong-yu, MAO Xin-rui, XIN Dawei, HU Zhen-bang, WU Xiao-xia, JIANG Hong-wei, QI Zhao-ming, CHEN Qing-shan
    2018, 17(08): 1727-1735.  DOI: 10.1016/S2095-3119(17)61862-8
    Abstract ( )   PDF in ScienceDirect  
    Soybean is a global principal source of edible plant oil.  As more soybean oil-related quantitative trait loci (QTLs) have been located in the collective genome, it is urgent to establish a classification system for these distributed QTLs.  A collinear platform may be useful to characterize and identify relationships among QTLs as well as aid in novel gene discovery.  In this study, the collinearity MCScanX algorithm and collective soybean genomic information were used to construct collinearity blocks, to which soybean oil-related QTLs were mapped.  The results demonstrated that 666 collinearity blocks were detected in the soybean genome across 20 chromosomes, and 521 collinearity relationships existed in 231 of the 242 effective soybean oil-related QTLs.  This included 214 inclusion relationships and 307 intersecting relationships.  Among them, the collinearity among QTLs that are related to soybean oil content was shown on a maximum of seven chromosomes and minimum of one chromosome, with the majority of QTLs having collinearity on two chromosomes.  Using overlapping hotspot regions in the soybean oil QTLs with collinearity, we mined for novel oil content-related genes.  Overall, we identified 23 putatively functional genes associated with oil content in soybean and annotated them using a number of annotation databases.  Our findings provide a valuable framework for elucidating evolutionary relationships between soybean oil-related QTLs and lay a foundation for functional marker-assisted breeding relating to soybean oil content.
    Silencing of OsXDH reveals the role of purine metabolism in dark tolerance in rice seedlings
    HAN Rui-cai, Adnan Rasheed, WANG Yu-peng, WU Zhi-feng, TANG Shuang-qin, PAN xiao-hua, SHI Qing-hua, WU Zi-ming
    2018, 17(08): 1736-1744.  DOI: 10.1016/S2095-3119(18)61939-2
    Abstract ( )   PDF in ScienceDirect  
    Xanthine dehydrogenase (XDH) is a crucial enzyme involved in purine metabolism.   To evaluate the effect of XDH deficiency on rice growth during dark treatment, wild type (WT) Nipponbare (Oryza sativa L.) and two independent transgenic lines with severe RNAi suppression (xdh3 and xdh4) were used in the present experiment.  Under normal growth conditions, chlorophyll levels and biomass were indistinguishable between WT and the two RNAi transgenic lines, but XDH enzyme activity and ureide levels were suppressed in XDH RNAi transgenic lines.  When XDH RNAi transgenic lines were subjected to dark treatment, chlorophyll content and biomass were significantly decreased, while O2· production rate and malonaldehyde (MDA) were significantly increased compared to WT.  The spraying test of exogenous allantoin raised chlorophyll content and biomass and reduced O2· production rate and MDA in WT and both transgenic lines, and it also simultaneously reduced differences between RNAi and WT plants caused by XDH deficiency in growth potential and anti-oxidative capacity under dark treatment.  These results suggested that fully functional purine metabolism plays an important role in reducing the sensitivity of rice seedlings to dark stress.
    How plant density affects maize spike differentiation, kernel set, and grain yield formation in Northeast China?
    ZHANG Ming, CHEN Tao, Hojatollah Latifmanesh, FENG Xiao-min, CAO Tie-hua, QIAN Chun-rong, DENG Ai-xing, SONG Zhen-wei, ZHANG Wei-jian
    2018, 17(08): 1745-1757.  DOI: 10.1016/S2095-3119(17)61877-X
    Abstract ( )   PDF in ScienceDirect  
    A two-year field experiment was conducted to evaluate the effects of plant density on tassel and ear differentiation, anthesis-silking interval (ASI), and grain yield formation of two types of modern maize hybrids (Zhongdan 909 (ZD909) as tolerant hybrid to crowding stress, Jidan 209 (JD209) and Neidan 4 (ND4) as intolerant hybrids to crowding stress) in Northeast China.  Plant densities of 4.50×104 (D1), 6.75×104 (D2), 9.00×104 (D3), 11.25×104 (D4), and 13.50×104 (D5) plants ha–1 had no significant effects on initial time of tassel and ear differentiation of maize.  Instead, higher plant density delayed the tassel and ear development during floret differentiation and sexual organ formation stage, subsequently resulting in ASI increments at the rate of 1.2–2.9 days on average for ZD909 in 2013–2014, 0.7–4.2 days for JD209 in 2013, and 0.5–3.7 days for ND4 in 2014, respectively, under the treatments of D2, D3, D4, and D5 compared to that under the D1 treatment.  Total florets, silking florets, and silking rates of ear showed slightly decrease trends with the plant density increasing, whereas the normal kernels seriously decreased at the rate of 11.0–44.9% on average for ZD909 in 2013–2014, 2.0–32.6% for JD209 in 2013, and 9.7–28.3% for ND4 in 2014 with the plant density increased compared to that under the D1 treatment due to increased florets abortive rates.  It was also observed that 100-kernel weight of ZD909 showed less decrease trend compared that of JD209 and ND4 along with the plant densities increase.  As a consequence, ZD909 gained its highest grain yield by 13.7 t ha–1 on average at the plant density of 9.00×104 plants ha–1, whereas JD209 and ND4 reached their highest grain yields by 11.7 and 10.2 t ha–1 at the plant density of 6.75×104 plants ha–1, respectively.  Our experiment demonstrated that hybrids with lower ASI, higher kernel number potential per ear, and relative constant 100-kernel weight (e.g., ZD909) could achieve higher yield under dense planting in high latitude area (e.g., Northeast China).
    Fatty acid analysis in the seeds of 50 Paeonia ostii individuals from the same population
    WEI Xiao-bao, XUE Jing-qi, WANG Shun-li, XUE Yu-qian, LIN Huan, SHAO Xing-feng, XU Dong-hui, ZHANG Xiu-xin
    2018, 17(08): 1758-1768.  DOI: 10.1016/S2095-3119(18)61999-9
    Abstract ( )   PDF in ScienceDirect  
    Tree peony seeds are rich in α-linolenic acid (ALA), and the peony seed oil is now being produced in China. Paeonia ostii is the most widely used tree peony species for oil extraction, which is commercially called Fengdan and treated as a single cultivar. Here, 50 P. ostii individuals from the same population in northern China were randomly selected for fatty acids (FAs) analysis. Thirteen FAs were isolated, and the most abundant five were palmitic acid (5.31–6.99%), stearic acid (1.22–2.76%), oleic acid (18.78–28.15%), linoleic acid (11.86–26.10%), and ALA (41.11–57.51%). There were significant individual differences of plants in FA quality and quantity and the linoleic acid content in Plant No. 48 even exceeded the scope of 1–99%. Further statistical analysis indicated that most of the individual FAs, saturated FAs, unsaturated FAs, and total FAs levels showed significant positive correlations to each other, whereas the seed yield per plant was independent and not correlated to the factors mentioned above. Ward’s hierarchical clustering results grouped the 50 plants into four clusters based on FA contents and seed yield, and the seven plants in Cluster IV were identified as good candidates for oil production. Our results confirmed that the individual differences did occur in P. ostii and Fengdan cannot be simply treated as one uniform cultivar. Also, these results may help simplify the selection of plants for oil peony breeding and accelerate the development of the oil peony industry.
    Enhancement of the transfection efficiency of DNA into Crocus sativus L. cells via PEI nanoparticles
    Behnam Firoozi, Nasser Zare, Omid Sofalian, Parisa Sheikhzade-Mosadegh
    2018, 17(08): 1768-1778.  DOI: 10.1016/S2095-3119(18)61985-9
    Abstract ( )   PDF in ScienceDirect  
    Over the past decade, several natural and synthetic cationic polymers have been utilized for gene delivery into cells.  Among them, polyethylenimine (PEI) was used for gene therapy successfully.  The present study investigated the effect of PEI and ultrasound waves on ssDNA delivery into saffron cells.  Gel retardation, dynamic light scattering (DLS) and scanning electron microscopy (SEM) assays were employed to determine the physicochemical properties of PEI/f-DNA  polyplex (complex of PEI and  fluorescently labeled DNA).  Moreover, the cytotoxicity of PEI, PEI/f-DNA polyplex and ultrasound were investigated on saffron cells at different concentrations.  The gel retardation results indicated that the formation and neutralization of the PEI/f-DNA polyplex were completed at N/P=5.  The particle size distribution of the polyplexes was from 50 to 122 nm.  The experimental results revealed that the cytotoxicity of the PEI/f-DNA polyplex was lower than that of PEI alone, hence the cells showed both dose- and exposure duration-dependent responses.  Furthermore, the viability of saffron cells declined extremely after 5 and 10 min sonication but this reduction was not significant at 2 min exposure duration.  The results also indicated that the combined utilization of ultrasound and PEI nanoparticles increased the transfection efficiency of saffron cells up to two times higher than those obtained by PEI or ultrasound separately.
    Plant Protection
    Population genetic structure of Chinese Puccinia triticina races based on multi-locus sequences
    LIU Tai-guo, GE Run-jing, MA Yu-tong, LIU Bo, GAO Li, CHEN Wan-quan
    2018, 17(08): 1779-1789.  DOI: 10.1016/S2095-3119(18)61923-9
    Abstract ( )   PDF in ScienceDirect  
    Puccinia triticina, the causal agent of wheat leaf rust, is one of the most devastating rust fungi attacking wheat worldwide.  Seventy-six isolates of the wheat leaf rust pathogen from Yunnan, Sichuan, Gansu and Henan provinces, China, were tested on wheat leaf rust differentials and the population structure was analyzed using four presumably neutral partial sequence markers such as elongation factor-1α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB) and the second largest RNA polymerase subunit (RPB2).  The phenotypic diversity of Yunnan and Sichuan populations was higher than that of Gansu and Henan populations.  The four populations were separated into two clusters based on the pathogenic data.  A total of 12 single nucleotide polymorphisms (SNPs) and 32 haplotypes were identified among the four sequences.  The 32 haplotypes were divided into two clusters in a neighbor-joining tree.  Bayesian analyses also identified two clusters.  Pairwise Fst between populations in different regions were significantly different (P<0.05).  Analysis of molecular variance (AMOVA) indicated that 68% of the total genetic variation was within populations. 
    Genomic and transcriptomic insights into cytochrome P450 monooxygenase genes involved in nicosulfuron tolerance in maize (Zea mays L.)
    LIU Xiao-min, XU Xian, LI Bing-hua, YAO Xiao-xia, ZHANG Huan-huan, WANG Gui-qi, HAN Yu-jun
    2018, 17(08): 1790-1799.  DOI: 10.1016/S2095-3119(18)61921-5
    Abstract ( )   PDF in ScienceDirect  
    Postemergence application of nicosulfuron for weed control in maize fields can cause great damage to certain maize inbred lines and hybrids.  Two maize genotypes, tolerant inbred (HBR) and sensitive inbred (HBS), were found to significantly differ in their phenotypic responses to nicosulfuron, with the EC50 (50% effective concentration) values differed statistically (763.6 and 5.9 g a.i. ha–1, respectively).  Pre-treatment with malathion, a known cytochrome P450 inhibitor, increased nicosulfuron injury in both HBR and HBS.  Our results support the hypothesis that nicosulfuron selectivity in maize is associated with cytochrome P450 metabolism.  Further analysis of the maize genome resulted in the identification of 314 full length cytochrome P450 monooxygenase (CYP) genes.  These genes were classified into 2 types, 10 clans and 44 families.  The CYP71 clan was represented by all A-type genes (168) belonging to 17 families.  Nine clans possessed 27 families containing 146 non-A-type genes.  The consensus sequences of the heme-binding regions of A-type and non-A-type CYP proteins are ‘PFGXGRRXCPG’ and ‘FXXGPRXCXG’, respectively.  Illumina transcriptome sequence results showed that there were 53 differentially expressed CYP genes on the basis of high variation in expression between HBS and HBR, nicosulfuron-treated and untreated samples.  These genes may contribute to nicosulfuron tolerance in maize.  A hierarchical clustering analysis obtained four main clusters named C1 to C4 in which 4, 15, 21, and 13 CYP genes were found in each respective cluster.  The expression patterns of some CYP genes were confirmed by RT-qPCR analysis.  The research will improve our understanding of the function of maize cytochrome P450 in herbicide metabolism.
    Plant Protection
    Automatic image segmentation method for cotton leaves with disease under natural environment
    ZHANG Jian-hua, KONG Fan-tao, WU Jian-zhai, HAN Shu-qing, ZHAI Zhi-fen
    2018, 17(08): 1800-1814.  DOI: 10.1016/S2095-3119(18)61915-X
    Abstract ( )   PDF (31718KB) ( )  
    In order to improve the image segmentation performance of cotton leaves in natural environment, an automatic segmentation model of diseased leaf with active gradient and local information is proposed.  Firstly, a segmented monotone decreasing edge composite function is proposed to accelerate the evolution of the level set curve in the gradient smooth region.  Secondly, canny edge detection operator gradient is introduced into the model as the global information.  In the process of the evolution of the level set function, the guidance information of the energy function is used to guide the curve evolution according to the local information of the image, and the smooth contour curve is obtained.  And the main direction of the evolution of the level set curve is controlled according to the global gradient information, which effectively overcomes the local minima in the process of the evolution of the level set function.  Finally, the Heaviside function is introduced into the energy function to smooth the contours of the motion and to increase the penalty function ?(x) to calibrate the deviation of the level set function so that the level set is smooth and closed.  The results showed that the model of cotton leaf edge profile curve could be obtained in the model of cotton leaf covered by bare soil, straw mulching and plastic film mulching, and the ideal edge of the ROI could be realized when the light was not uniform.  In the complex background, the model can segment the leaves of the cotton with uneven illumination, shadow and weed background, and it is better to realize the ideal extraction of the edge of the blade.  Compared with the Geodesic Active Contour (GAC) algorithm, Chan-Vese (C-V) algorithm and Local Binary Fitting (LBF) algorithm, it is found that the model has the advantages of segmentation accuracy and running time when processing seven kinds of cotton disease leaves images, including uneven lighting, leaf disease spot blur, adhesive diseased leaf, shadow, complex background, unclear diseased leaf edges, and staggered condition.  This model can not only conduct image segmentation of cotton leaves under natural conditions, but also provide technical support for the accurate identification and diagnosis of cotton diseases.
    The impact of allelochemicals on the differential expression of symbiotic bacteria in cotton aphids
    LIU Ying, LIANG Ping-zhuo, LI Fen, MA Kang-sheng, CHEN Xue-wei, CHEN An-qi, LIANG Pei, GAO Xi-wu
    2018, 17(08): 1815-1821.  DOI: 10.1016/S2095-3119(17)61838-0
    Abstract ( )   PDF in ScienceDirect  
    Insects have developed a good adaptive mechanism in response to environmental stresses in the long-term evolution.
    They have developed a helpful metabolism system to resist plant allelochemicals. Insects also harbor different kinds of
    symbiotic bacteria, which provide them a competitive advantage. Here, using cotton aphid as an example, we investigated
    the effects of four plant allelochemicals on the differential expression of symbiotic bacteria based on transcriptome data.
    We also studied the composition of symbiotic bacteria and function on pathway level in three kinds of aphids. We found that
    the bacteria have a significant role in resisting the plant allelochemicals stress and host plant selection by aphids. These
    results should be useful to investigate the environmental adaption mechanism of aphids in the view of symbiotic bacteria.
    These results would offer a new insight for improving strategy of aphids and developing new pest control systems.
    Pyraclostrobin-loaded poly (lactic-co-glycolic acid) nanospheres: Preparation and characteristics
    YIN Ming-ming, ZHENG Yu, CHEN Fu-liang
    2018, 17(08): 1822-1832.  DOI: 10.1016/S2095-3119(17)61839-2
    Abstract ( )   PDF in ScienceDirect  
    We used poly (lactic-co-glycolic acid) (PLGA) as a carrier polymer for pyraclostrobin-loaded nanospheres.  Using the ultrasound emulsification-solvent evaporation method, the physicochemical characteristics and release properties of the pyraclostrobin-loaded nanospheres were studied by dialysis.  The optimal nanospheres prepared had a diameter of 0.6 μm, an active ingredient loading of 17.2%, and a loading rate of 89.7%.  Infrared spectroscopy data and differential scanning calorimetry revealed that pyraclostrobin was successfully embedded in the carrier PLGA, and photostability tests indicated enhanced ultraviolet resistance of pyraclostrobin-loaded PLGA nanospheres nanospheres.  Release property testing indicated that smaller particles had a faster release rate.  Nanospheres also had a faster release rate in slightly acidic and slightly basic environments than in a neutral condition.  Agitated nanospheres had a faster release rate than immobile nanospheres.  The cumulative release kinetics of pyraclostrobin-loaded nanospheres was consistent with the first order kinetic equation and the Weibull equation.
    Animal Science · Veterinary Medicine
    The effects of step-wise improvement of forage combination in total mixed rations on fatty acid profile in the rumen and milk of Holstein cows
    BAI Sarvvl, CAO Zhi-jun, JIN Xin, WANG Ya-jing, YANG Hong-jian, LI Sheng-li
    2018, 17(08): 1833-1842.  DOI: 10.1016/S2095-3119(18)61941-0
    Abstract ( )   PDF (899KB) ( )  
    Five lactating Holstein cows in a 5×5 Latin square experiment were fed five high-concentrate total mixed rations (TMRs) to investigate the effects of step-wise improvement of forage combination on ruminal and milk fatty acid profiles.  The ratio of concentrate to forage was fixed as 61:39, and the step-wise improvement of forage combination was applied as: TMR1, a ration containing corn stover; TMR2, a ration containing corn stover and ensiled corn stover; TMR3, a ration containing ensiled corn stover and Chinese wild ryegrass hay (Leymus chinensis); TMR4, a ration containing the ryegrass hay and whole corn silage; TMR5, a ration containing the ryegrass hay, whole corn silage and alfalfa hay.  The TMRs were offered to the cows twice daily at 0700 and 1900 h.  The entire experiment was completed in five periods, and each period lasted for 18 days.  Diurnal samples of rumen fluids were collected at 0100, 0700, 1300 and 1900 h (day 16); 0300, 0900, 1500 and 2100 h (day 17); and 0500, 1100, 1700 and 2300 h (day 18).  The step-wise improvement of forage combination increased energy and crude protein contents and decreased fibre content.  As a result, the step-wise improvement of forage combination increased dry matter intake and milk yield (P<0.05).  The step-wise improvement increased dietary content of linolenic acid (C18:3n-3), but did not alter dietary proportions of palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1cis-9), linoleic acid (C18:2n-6) and arachidic acid (C20:0).  In response to the forage combination, ruminal concentration of C16:0, C18:2n-6 and C18:3n-3 linearly increased against their dietary intakes (P<0.10).  The step-wise improvement increased milk contents of C10:0, C12:0, C14:0, C16:0, C18:2n-6 and C18:3n-3 (P<0.10) and decreased milk contents of C18:0 and C18:1cis-9 (P<0.05).  Milk yields of C16:0, C18:1cis-9, C18:2n-6 and C18:3n-3 were linearly increased by the increase of these fatty acids in the rumen (R2≥0.79, P<0.05), and milk yields of C18:2n-6 and C18:3n-3 were also positively correlated with dietary intake of these fatty acids (R2≥0.85, P<0.05).  The step-wise improvement increased the transfer efficiencies from feed to milk for C18:2n-6 from 11.8 to 14.2% and for C18:3n-3 from 19.1 to 22.3%.  In a brief, along with the step-wise improvement of forage combination, more dietary linoleic and linolenic acids might escape microbial hydrogenation in the rumen and consequently accumulated in milk fat though these fatty acids were present in low concentrations in ruminal fluids.  The step-wise improvement of forage combinations could be recommended as a dietary strategy to increase the transfer efficiency of linoleic and linolenic acids from feed to milk.
    iTRAQ-based quantitative proteomic analysis reveals key pathways responsible for scurs in sheep (Ovis aries)
    HE Xiao-hong, CHEN Xiao-fei, PU Ya-bin, GUAN Wei-jun, SONG Shen, ZHAO Qian-jun, LI Xiangchen, JIANG Lin, MA Yue-hui
    2018, 17(08): 1843-1851.  DOI: 10.1016/S2095-3119(17)61894-X
    Abstract ( )   PDF in ScienceDirect  
    Scurs is a horn phenotype that exhibits as small corneous structures on the skull due to the deformed development of horn tissues.  Previous genome-wide association analysis of scurs in Soay sheep showed a significant association to the polled locus, relaxin-like receptor 2 (RXFP2).  However, the molecular mechanism underlying the development of scurs remains largely unknown.  In the present study, we performed an iTRAQ-based quantitative proteomic analysis of horn tissues from both scurs and normal two-horned and four-horned individuals among Altay sheep to identify the differentially expressed proteins (DEPs) responsible for the scurs phenotype.  In total, 232 proteins showed significant differential expression, and the most significant Gene ontology categories were the adhesion processes (biological adhesion (P=4.07×10–17) and cell adhesion (P=3.7×10–16)), multicellular organismal process (single-multicellular organism process (P=2.06×10–11) and multicellular organismal process (P=2.29×10–11)) and extracellular processes (extracellular matrix organization (P=4.77×10–16) and extracellular structure organization (P=4.93×10–16)).  Kyoto encyclopedia of genes and genomes (KEGG) analysis showed that extracellular matrix (ECM)-receptor interactions and focal adhesion pathways were the most significant pathways.  This finding is consistent with the reduced formation of extracellular matrix in scurs and the development of deformed horn tissues.  Our study helps to elucidate the inheritance pattern of sheep horn traits from the perspectives of downstream expressed proteins.
    Agro-ecosystem & Environment
    Effects of long-term green manure application on the content and structure of dissolved organic matter in red paddy soil
    GAO Song-juan, GAO Ju-sheng, CAO Wei-dong, ZOU Chun-qin, HUANG Jing, BAI Jin-shun, DOU Fu-gen
    2018, 17(08): 1852-1860.  DOI: 10.1016/S2095-3119(17)61901-4
    Abstract ( )   PDF in ScienceDirect  
    Dissolved organic matter (DOM) plays important roles in soil biogeochemistry activity and nutrients transportation in soils, but studies regarding the long-term effects of green manures on the content and structure of DOM in red paddy soil have not been reported yet.  A long-term green manure experiment established in 1982 was utilized to test the DOM contents in different treatments, and the spectral characteristics of DOM were investigated by using ultraviolet-visible (UV-Vis) spectrometry and Fourier transform infrared (FTIR) spectrometry.  The experiment included four cropping systems: rice-rice-milk vetch (RRV), rice-rice-rape (RRP), rice-rice-ryegrass (RRG) and rice-rice-winter fallow (RRF), among them, milk vetch, rape, and ryegrass are popular winter green manure species in southern China.  The results showed that the content of dissolved organic carbon (DOC), which is widely used to estimate the concentration of DOM, was significantly promoted after the incorporation of green manures compared with the other sampling stages.  The contents of aromatic groups and the degree of humification of DOM increased in RRV and RRP, suggesting more complex compositions of the soil DOM after long-term application of milk vetch and rape.  The contents of phenol, alcohol and carboxylic acid group at the mature stage of early rice were significantly higher than those at the stage of after green manures turned over, especially for the RRV treatment.  The absorption ratio of FTIR indicated that winter plantation of rape increased the aromatic-C/aliphatic-C ratio, and ryegrass increased the aromatic-C/carboxyl-C ratio.  In conclusion, long-term planting of milk vetch and rape as green manures increased the degree of aromaticity, humification and average molecular weight of DOM, and made the DOM more stable in red paddy soil. 
    Accumulation and bioavailability of heavy metals in a soil-wheat/ maize system with long-term sewage sludge amendments
    YANG Guo-hang, ZHU Guang-yun, LI He-lian, HAN Xue-mei, LI Ju-mei, MA Yi-bing
    2018, 17(08): 1861-1870.  DOI: 10.1016/S2095-3119(17)61884-7
    Abstract ( )   PDF (1049KB) ( )  
    A long-term field experiment was carried out with a wheat-maize rotation system to investigate the accumulation and bioavailability of heavy metals in a calcareous soil at different rates of sewage sludge amendment.  There are significant linear correlations between the contents of Hg, Zn, Cu, Pb, and Cd in soil and sewage sludge amendment rates.  By increasing 1 ton of applied sludge per hectare per year in soil, the contents of Hg, Zn, Cu, Pb, and Cd in soil increased by 6.20, 619, 92.9, 49.2, and 0.500 µg kg–1, respectively.  For Hg, sewage sludge could be safely applied to the soil for 18 years at an application rate of 7.5 t ha–1 before content exceeded the soil environmental quality standards in China (1 mg kg–1).  The safe application period for Zn is 51 years and is even longer for other heavy metals (112 years for Cu, 224 years for Cd, and 902 years for Pb) at an application rate of 7.5 t ha–1 sewage sludge.  The contents of Zn and Ni in wheat grains and Zn, Cu, and Cr in maize grains increased linearly with increasing sewage sludge amendment rates.  The contents of Zn, Cr, and Ni in wheat straws and Zn, Cu, and As in maize straws were positively correlated with sewage sludge amendment rates, while the content of Cu in wheat straws and Cr in maize straws showed the opposite trend.  The bioconcentration factors of the heavy metals in wheat and maize grains were found to be in the order of Zn>Cu>Cd>Hg>Cr=Ni>Pb>As.  Furthermore, the bioconcentration factors of heavy metals in wheat were greater than those in maize, indicating that wheat is more sensitive than maize as an indicator plant.  These results will be helpful in developing the critical loads for sewage sludge amendment in calcareous soils.
    Changes in soil biochemical indicators at different wheat growth stages under conservation-based sustainable intensification of rice-wheat system
    Tanushree Bera, Sandeep Sharma, H. S. Thind, Yadvinder-Singh, H. S. Sidhu, M. L. Jat
    2018, 17(08): 1871-1880.  DOI: 10.1016/S2095-3119(17)61835-5
    Abstract ( )   PDF in ScienceDirect  
    Soil microbes play critical roles in soil biogeochemistry, soil biological health and crop productivity.  The current study evaluated the effects of tillage and residue management on changes in soil biochemical indicators at different growth stages of wheat after 5 years of rice-wheat system.  Nine treatment combinations of tillage, crop establishment and crop residue management included three main plot treatments applied to rice: (1) conventional till direct dry seeded rice (CTDSR), (2) zero till direct dry seeded rice (ZTDSR), and (3) conventional puddled manual transplanted rice (CTPTR) and three sub-plot treatments in subsequent wheat: (1) conventional tillage with rice residue removed (CTW-R), (2) zero tillage with rice residue removed (ZTW-R) and (3) zero tillage with rice residue retained as surface mulch (ZTW+R).  Irrespective of rice treatments, ZTW+R treatment had higher soil biochemical indicators compared with ZTW-R and CTW-R at all the growth stages of wheat.  Generally, all the biochemical indicators were the highest at the flowering stage of wheat.  Residual effect of rice treatments was also significant on biochemical quotients in wheat, which were the highest under ZTDSR followed by CTDSR and CTPTR.  The present study provided three sensitive and reliable biochemical indicators (microbial biomass, basal soil respiration and microbial quotient) which respond rapidly to change in tillage and residue management practices in RWS of South Asia.
    Impacts of invasive Iris pseudacorus L. (yellow flag) establishing in an abandoned urban pond on native semi-wetland vegetation
    Daisuke Hayasaka, Shingo Fujiwara, Taizo Uchida
    2018, 17(08): 1881-1887.  DOI: 10.1016/S2095-3119(17)61831-8
    Abstract ( )   PDF in ScienceDirect  
    Iris pseudacorus L., intentionally introduced in Japan as an ornamental plant and to improve aquatic environments, has been declared a noxious species in the Invasive Alien Species Act of Japan due to the suspected high ecological risks to the local species and ecosystems.  Although prompt responses to I. pseudacorus have been sought to conserve local biodiversity, knowledge about its invasiveness is lacking.  Here, we report the relationship between the establishment of I. pseudacorus and floristic changes in semi-wetland vegetation of an abandoned urban pond (Aoike), Nara City, Nara Prepecture, Japan.  In total, 64 vascular plants were recorded in the pond, of which 50 were native species, seven were naturalized non-native, and seven were invasive species.  On the other hand, most of these vascular plants (42 species) were grassland species and only several aquatic plants (10 species) were found in this study pond.  The number of vascular plant species decreased significantly at quadrats with a coverage of I. pseudacorus above 50%.  In addition, tendencies of lower number of native species and concomitant higher number of invasive species were found with increasing coverage of I. pseudacorus.  From these results, we suggest that it is important to preferentially manage sites where the coverage of I. pseudacorus is above 50%, in order to preserve the local biodiversity.  Additionally, as recommended in the literature, it is essential that the cut reproductive organs are kept submerged under deep water for an effective control of I. pseudacorus
    Agricultural Economics and Management
    What determines irrigation efficiency when farmers face extreme weather events? A field survey of the major wheat producing regions in China
    SONG Chun-xiao, Les Oxley, MA Heng-yun
    2018, 17(08): 1888-1899.  DOI: 10.1016/S2095-3119(18)62006-4
    Abstract ( )   PDF (882KB) ( )  
    Water availability is a major constraint on grain production in China, therefore, improving irrigation efficiency is particularly important when agriculture faces extreme weather events.  This paper first calculates irrigation efficiency with a translog stochastic frontier production function and then investigates what happens when extreme weather events occur via a Tobit model.  The estimated results reveal several important features of irrigation practices: i) irrigation efficiency is lower when extreme weather events occur; ii) large variations in irrigation efficiency occur across irrigation facilities; iii) the farm plots exhibit an extreme distribution across efficiency levels; and iv) water-saving techniques, technology adoption, and the maintenance of farmers’ economic resilience are major determinants of irrigation efficiency.  Based on these results we propose the following recommendations: i) farmers should balance crop yield and water use; undertake relevant training programs and adopt water-saving techniques; ii) local governments and researchers should help farmers to find the optimal level of irrigation water use based on their own circumstances and provide better water-saving techniques and training programs rather than simply encouraging farmers to invest in irrigation facilities in the most extreme weather years; and iii) the income level of farm households should be increased so as to improve their resilience to natural disasters.
    Is the “One Province One Rate” premium policy reasonable for Chinese crop insurance? The case in Jilin Province
    ZHOU Xian-hua, LIAO Pu, WANG Ke
    2018, 17(08): 1900-1911.  DOI: 10.1016/S2095-3119(18)62032-5
    Abstract ( )   PDF in ScienceDirect  
    Crop insurance in China is currently adopting the premium pricing strategy of “One Province One Rate”, which appears to be in line with the systematic risk characteristics within crop insurance.  This research aims to investigate the theoretical rationalization of this pricing strategy and its implications using the spatial lag model and the county-level data from the 45 corn plant counties of Jilin Province, China.  Results corroborate that: (1) the spatial spillover effect of the corn yield risk is significant in Jilin but decreases rapidly when the risk unit includes more than eight counties; and (2) separating Jilin Province into eight risk zones for corn insurance will significantly reduce the high cross-subsidy phenomenon arising from the “One Province One Rate” strategy and shall benefit poor peasants in the region as well.  This paper not only proves the existence of a systematic risk of crop insurance but also reveals that the spatial correlation and systemic features of the crop yield risk do not create a solid foundation for the current pricing strategy of “One Province One Rate”.  These conclusions will undoubtedly provide important references and empirical evidence for the role of China’s crop insurance in poverty alleviation.
    First report of cereal cyst nematode (Heterodera filipjevi) on winter wheat in Shandong Province, China
    ZHEN Hao-yang, PENG Huan,ZHAO Hong-hai, QI Yong-hong, HUANG Wen-kun, KONG Ling-an, LIANG Chen, WEN Yan-hua, PENG De-liang
    2018, 17(08): 1912-1913.  DOI: 10.1016/S2095-3119(18)61965-3
    Abstract ( )   PDF in ScienceDirect  
    The cereal cyst nematodes (Heterodera avenae, Heterodera filipjevi, Heterodera latipons) are considered to be one of the most important plant parasitic nematodes attacking most cereals and can cause significant crop losses (Sikora 1988).  In China, H. filipjevi (Madzhidov 1981) Stelter, 1984, was first reported from Henan province (Peng et al. 2010) and a few years later in Anhui province and Xinjiang Uygur Autonomous Region (Peng et al. 2016, 2018) .  In December 2017, a survey for cereal cyst nematodes on winter wheat was conducted in Shandong Province, China.  A total of 79 samples that including roots and rhizosphere soil were collected.  Cysts and second-stage juveniles (J2s) were isolated from each soil sample using the sieving-decanting method.  Wheat roots were stained with acid fusion to observe the development of cereal cyst nematodes.  One sample collected from Yangzhuan Village in Huanggang Town, Shan County of Heze City (GPS 34°38´23.10´´N, 116°05´42.95´´E), Shandong Province, was found that the wheat roots were heavily parasitized by cyst nematodes, and most of the nematodes in roots had developed to fourth-stage (J4) in mid-December of 2017.  The morphological and molecular studies of cyst and J2s were carried out to confirm the identification of H. filipjevi in one winter wheat field soil and root sample from Shan County.  The cysts were lemon shaped with prominent vulval cone, brown to black in colour.  Cuticle with irregular zig-zag pattern.  Neck prominent, vulval cone bifenestrate with horseshoe-shaped fenestra, bullae and underbridge strongly developed.  The main morphometrics of cysts (n=8) were length (including neck) (688 to 948 μm, mean=794 μm, standard deviation=87 μm), width (465 to 620 μm, mean=529 μm, standard deviation=63 μm), neck length (71.5 to 126.3 μm, mean=86.5 μm, standard deviation=9.2 μm), fenestra length (43.8 to 71.3 μm, mean=58.0 μm, standard deviation=15.1 μm), fenestra width (19.8 to 32.0 μm, mean=25.0 μm, standard deviation=3.9 μm), length of vulval slit (8.1 to 9.7 μm, mean=9.1 μm, standard deviation=0.5 μm) and length of underbridge (64.5 to 101.3 μm, mean=82.6 μm, standard deviation=12.8 μm).  Measurements of J2s (n=10); body length (556.7 to 617.0 μm, mean=584.3 μm, standard deviation=23.2 μm); stylet (22.8 to 24.1 μm, mean=23.3 μm, standard deviation=0.4 μm), tail (59.6 to 68.6 μm, mean=65.8 μm, standard deviation=3.5 μm) and hyaline tail terminus (35.9 to 41.1 μm, mean=38.6 μm, standard deviation=2.1 μm).  Genomic DNA was isolated from single cysts (n=6), and the internal transcribed spacer regions were amplified with primers TW81 (5´-GTTTCCGTAGGTGAACCTGC-3´) and AB28 (5´-ATATGCTTAAGTTCAGCGGGT-3´) (Joyce et al. 1994) and 28S rDNA-D2/D3 regions were amplified with primers D2A (5´-ACAAGTACCGTGAGGGAAAGTTG-3´) and D3B (5´-TCGGAAGGAACCAGCTACTA-3´) (Subbotin et al. 2006).  The obtained internal transcribed spacer regions (ITSs) sequences (GenBank accession MG859977) is 99% identical to those of H. filipjevi from Turkey (KR704292.1 and KR704304.1), the United States (KP878490.1 and GU079654.1) and China (KY448473.1 and KY448473.1).  The obtained 28S rDNA-D2/D3 sequences (GenBank accession MG859980) also to be 99 to 100% identical to those of H. filipjevi from China (GU083597.1, KT314235.1, GU083592.1).  The species-specific primers of H. filipjevi (HfF1, 5´-CAGGACGAAACTCATTCAACCAA-3´; HfR1, 5´-AGGGCGAACAGGAGAAGATTAGA-3´) were also used to identify this population (Peng et al. 2013), the specific band was obtained species-specific primers of H. filipjevi.  Based on the morphological and molecular data, the species of the cyst-forming nematode was identified as H. filipjevi.  As far as we know, this is the first report of H. filipjevi in Shandong Province, China.  The population density of H. filipjevi were found much higher than those of other CCN, it can serious infect winter wheat at seedling stage which often cause economically damaging to wheat, so the spread of H. filipjevi would be a risk for the cereal production of Shandong province.