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2017 Vol. 16 No. 10 Previous Issue    Next Issue

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Review
Crop Science
Horticulture
Plant Protection
Animal Science · Veterinary Medicine
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Review

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Ecology and management of the black inch worm, Hyposidra talaca Walker (Geometridae: Lepidoptera) infesting Camellia sinensis (Theaceae): A review Somnath Roy, Soma Das, Gautam Handique, Ananda Mukhopadhyay, Narayanannair Muraleedharan 2017, 16(10): 2115-2127.  DOI: 10.1016/S2095-3119(16)61573-3 Abstract ( )   PDF in ScienceDirect   The black inch worm, Hyposidra talaca (Walker) (Geometridae: Lepidoptera) has earned considerable importance as a defoliator during last decade in north east India.  Characteristic features of H. talaca, such as switching from wild plants to Camellia sinensis, and completion of 6–8 generations in a year without winter diapause appear to be the major reasons for persistence of the defoliator on C. sinensis.  There are reports on the aggressive infestation of the pest on C. sinensis than on alternate host plants and development of high tolerance/resistance to certain insecticides.  Till date, more than one hundred alternate host plants have been recorded for H. talaca, but with very few natural enemies.  To manage this pest chemically, synthetic pesticides are widely used.  Integrated management is recently being encouraged wherein cultural, mechanical, physical, biological and chemical methods have been contemplated.  This review collates the work and literature on the ecology of H. talaca and offers an analysis of the problems encountered in managing the defoliator in tea plantations.  Further, future directions for better management of H. talaca are suggested.

Crop Science

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Significant association of the novel Rf4-targeted SNP marker with the restorer for WA-CMS in different rice backgrounds and its utilization in molecular screening CHEN Li-kai, YAN Xian-cheng, DAI Jun-hao, CHEN Si-ping, LIU Yong-zhu, WANG Hui, CHEN Zhiqiang, GUO Tao 2017, 16(10): 2128-2135.  DOI: 10.1016/S2095-3119(16)61620-9 Abstract ( )   PDF in ScienceDirect      In the rice cytoplasmic-genetic male sterility (CMS) system, the combination of a CMS line, maintainer line and restorer line carrying the restorer gene to restore fertility, is indispensable for the development of hybrids. However, the process of screening for the trait of fertility restoration is laborious and time-consuming. In the present study, we analyzed the nucleotide sequence of the Rf4 gene, which is the major locus controlling fertility restoration, to identify allele-specific variation. A single nucleotide polymorphism (SNP) A/C at +474 in the coding sequence (CDS) was found to be capable of strictly distinguishing groups of alleles Rf4 (A) and rf4 (C). Using KASP genotyping, this valuable SNP was converted to an allele-specific PCR marker. We evaluated and validated the marker among three-line parents with different backgrounds, and the results revealed a complete correlation between SNP alleles and the fertility restoration phenotype. Molecular screening was subsequently carried out for the presence of alleles of Rf4 and Rf3 among 328 diverse rice cultivars with worldwide distribution. The results demonstrate that this SNP marker could be the optimal choice for the molecular identification of potential restorers.

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Genetic behavior of Triticum aestivum–Dasypyrum villosum translocation chromosomes T6V#4S·6DL and T6V#2S·6AL carrying powdery mildew resistance LIU Chang, YE Xing-guo, WANG Mei-jiao, LI Shi-jin, LIN Zhi-shan 2017, 16(10): 2136-2144.  DOI: 10.1016/S2095-3119(16)61568-X Abstract ( )   PDF in ScienceDirect   T6V#2S·6AL and T6V#4S·6DL translocation chromosomes developed from the cross of wheat and different Dasypyrum villosum accessions have good powdery mildew (PM) resistance, but their pairing and pyramiding behavior remains unclear.  Results in this study indicated that the pairing frequency rate of the two differently originated 6VS chromosomes in their F1 hybrid was 18.9% according to genomic in situ hybridization (GISH); the PM resistance plants in the F2 generation from the cross between T6V#4S·6DL translocation line Pm97033 and its PM susceptible wheat variety Wan7107 was fewer than expected.  However, the ratio of the resistant vs. the susceptible plants of 15:1 in the F2 generation derived from the cross between the two translocation lines of T6V#2S·6AL and T6V#4S·6DL fitted well.  Plants segregation ratio (homozygous:heterozygous:lacking) revealed by molecular marker for T6V#4S·6DL or T6V#2S·6AL in their F2 populations fitted the expected values of 1:2:1 well, inferring that the pairing of the two alien chromosome arms facilitates the transmission of T6V#4S·6DL from the F1 to the F2 generation.  A quadrivalent was also observed in 21% of pollen mother cells (PMCs) of homozygote plants containing the two pairs of translocated chromosomes.  The chromosome pairing between 6V#2S and 6V#4S indicates that it will be possible to obtain recombinants and clarify if the PM resistance determinant on one alien chromosome arm is different from that on the other.

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Conditional and unconditional QTLs mapping of gluten strength in common wheat (Triticum aestivum L.) LIU Tong-tong, LIU Kai, WANG Fang-fang, ZHANG Ying, LI Qing-fang, ZHANG Kai-ran, XIE Chu-peng, TIAN Ji-chun, CHEN Jian-sheng 2017, 16(10): 2145-2155.  DOI: 10.1016/S2095-3119(16)61564-2 Abstract ( )   PDF in ScienceDirect       Dissecting the genetic relationships among gluten-related traits is important for high quality wheat breeding. Quantitative trait loci (QTLs) analysis for gluten strength, as measured by sedimentation volume (SV) and gluten index (GI), was performed using the QTLNetwork 2.0 software. Recombinant inbred lines (RILs) derived from the winter wheat varieties Shannong 01-35×Gaocheng 9411 were used for the study. A total of seven additive QTLs for gluten strength were identified using an unconditional analysis. QGi1D-13 and QSv1D-14 were detected through unconditional and conditional QTLs mapping, which explained 9.15–45.08% of the phenotypic variation. QTLs only identified under conditional QTL mapping were located in three marker intervals: WPT-3743–GLU-D1 (1D), WPT-7001–WMC258 (1B), and WPT-8682–WPT-5562 (1B). Six pairs of epistatic QTLs distributed nine chromosomes were identified. Of these, two main effect QTLs (QGi1D-13 and QSv1D-14) and 12 pairs of epistatic QTLs were involved in interactions with the environment. The results indicated that chromosomes 1B and 1D are important for the improvement of gluten strength in common wheat. The combination of conditional and unconditional QTLs mapping could be useful for a better understanding of the interdependence of different traits at the QTL molecular level.

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iTRAQ-based quantitative proteome characterization of wheat grains during filling stages CUI Yong, YANG Ming-ming, DONG Jian, ZHAO Wan-chun, GAO Xiang 2017, 16(10): 2156-2167.  DOI: 10.1016/S2095-3119(16)61583-6 Abstract ( )   PDF in ScienceDirect   Using isobaric tags for relative and absolute quantification (iTRAQ) and associated analytic technologies, we have cataloged and compared 7 069 unique wheat proteins expressed during four substages of the filling stage.  Among them, 859 are differentially expressed, showing at least a 2-fold difference in concentration across substages.  Differentially expressed proteins (DEPs) includind high-molecular weight glutenin subunit (W5AIU1), low-molecular weight glutenin subunit (Q8W3V4), gliadin/avenin-like seed protein (D2KFG9), and avenin-like protein (W5DVL2), all of which have previously been identified as important for nutritional quality and bread-making properties, and all of which were found to increase at the latter stages of development.  We have applied statistical techniques to group the proteins into hierarchical clusters, and have consulted databases to infer functional and other relationships among the identified proteins.

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Ipomoea batatas HKT1 transporter homolog mediates K+ and Na+ uptake in Saccharomyces cerevisiae PARK Sung-chul, YU Yi-cheng, KOU Meng, YAN Hui, TANG Wei, WANG Xin, LIU Ya-ju, ZHANG Yun-gang, KWAK Sang-soo, MA Dai-fu, SUN Jian, LI Qiang 2017, 16(10): 2168-2176.  DOI: 10.1016/S2095-3119(16)61570-8 Abstract ( )   PDF in ScienceDirect   Soil salinity causes the negative effects on the growth and yield of crops. In this study, two sweet potato (Ipomoea batatas L.) cultivars, Xushu 28 (X-28) and Okinawa 100 (O-100), were examined under 50 and 100 mmol L–1 NaCl stress. X-28 cultivar is relatively high salt tolerant than O-100 cultivar. Interestingly, real-time quantitative polymerase chain reaction (RT-qPCR) results indicated that sweet potato high-affinity K+ transporter 1 (IbHKT1) gene expression was highly induced by 50 and 100 mmol L–1 NaCl stress in the stems of X-28 cultivar than in those of O-100 cultivar, but only slightly induced by these stresses in the leaves and fibrous roots in both cultivars. To characterize the function of IbHKT1 transporter, we performed ion-flux analysis in tobacco transient system and yeast complementation. Tobacco transient assay showed that IbHKT1 could uptake sodium (Na+). Yeast complementation assay showed that IbHKT1 could take up K+ in 50 mmol L–1 K+ medium without the presence of NaCl. Moreover, Na+ uptake significantly increased in yeast overexpressing IbHKT1. These results showed that IbHKT1 transporter could have K+-Na+ symport function in yeast. Therefore, the modes of action of IbHKT1 in transgenic yeast could differ from the mode of action of the other HKT1 transporters in class I. Potentially, IbHKT1 could be used to improve the salt tolerance nature in sweet potato.

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Modeling curve dynamics and spatial geometry characteristics of rice leaves ZHANG Yong-hui, TANG Liang, LIU Xiao-jun, LIU Lei-lei, CAO Wei-xing, ZHU Yan 2017, 16(10): 2177-2190.  DOI: 10.1016/S2095-3119(16)61597-6 Abstract ( )   PDF in ScienceDirect   The objective of this work was to develop a dynamic model for describing leaf curves and a detailed spatial geometry model of the rice leaf (including sub-models for unexpanded leaf blades, expanded leaf blades, and leaf sheaths), and to realize three-dimensional (3D) dynamic visualization of rice leaves by combining relevant models.  Based on the experimental data of different cultivars and nitrogen (N) rates, the time-course spatial data of leaf curves on the main stem were collected during the rice development stage, then a dynamic model of the rice leaf curve was developed using quantitative modeling technology.  Further, a detailed 3D geometric model of rice leaves was built based on the spatial geometry technique and the non-uniform rational B-spline (NURBS) method.  Validating the rice leaf curve model with independent field experiment data showed that the average distances between observed and predicted curves were less than 0.89 and 1.20 cm at the tilling and jointing stages, respectively.  The proposed leaf curve model and leaf spatial geometry model together with the relevant previous models were used to simulate the spatial morphology and the color dynamics of a single leaf and of leaves on the rice plant after different growing days by 3D visualization technology.  The validation of the leaf curve model and the results of leaf 3D visualization indicated that our leaf curve model and leaf spatial geometry model could efficiently predict the dynamics of rice leaf spatial morphology during leaf development stages.  These results provide a technical support for related research on virtual rice.

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Effect of plough pans on the growth of soybean roots in the black- soil region of northeastern China DONG Wen-cai, FU Qiang, WANG Quan-jiu, CAO Cheng-peng 2017, 16(10): 2191-2196.  DOI: 10.1016/S2095-3119(16)61567-8 Abstract ( )   PDF in ScienceDirect   Plough pans (PPs), common in the black-soil region of northeastern China, have significant effects on the root systems of crops.  We conducted a field experiment to study the distribution of soybean roots under the influence of PPs.  The soybean roots showed compensatory growth above the PP, with higher root length and weight in soil with a PP compared to those without a PP.  Roots were heavier and longer in the 15–75 cm soil layer without a PP than with a PP.  Soil porosity was lower in the PP and the soil below the PP, which likely decreased the oxygen content of the soil and induced more growth of roots above the PP.  The PP is also likely to decrease infiltration of rain-water and hinder the migration of nitrate downward, which in turn increased the density and length of soybean root hairs, which, hence, promoted growth.

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Drought-induced responses of organic osmolytes and proline metabolism during pre-flowering stage in leaves of peanut (Arachis hypogaea L.) ZHANG Ming, WANG Li-feng, ZHANG Kun, LIU Feng-zhen, WAN Yong-shan 2017, 16(10): 2197-2205.  DOI: 10.1016/S2095-3119(16)61515-0 Abstract ( )   PDF in ScienceDirect   Peanut (Arachis hypogaea L.), an improtant oil crop, usually encounters drought stress in the process of growth and development, especially at pre-flowering stage.  In order to gain insight into the drought tolerance potentials based on osmolyte accumulation and metabolism of proline aspects of peanut, pot experiments were conducted with a split-plot design in Tai’an, Shangdong Province, China in 2013 and 2014.  Pre-flowering drought (PFD) stress and optinum irrigation (control, CK) were served as the main plots and the two peanut cultivars Shanhua 11 and Hua 17 served as sub-plots.  Shanhua 11 was drought-tolerant cultivar and Hua 17 was drought-sensitive.  The content of soluble sugars, soluble protein, free proline and other free amino acids, the activities of enzymes involved in proline metabolism, and malondialdehyde (MDA) content and ion leakage were all investigated in the two cultivars at pre-flowering stage.  Results showed that PFD stress significantly increased the levels of soluble protein, free proline and free amino acid, and increased Δ1-pyrroline-5-carboxylate synthetase (P-5-CS, EC 2.7.2.11) activity in the leaves of drought-tolerant and drought-sensitive cultivars.  The activity of proline dehydrogenase (proDH) (EC 1.5.99.8) decreased under PFD stress in both cultivars.  The leaves of the tolerant cultivar maintained higher increments of osmolyte levels, lower increments of MDA content and ion leakage, as well as a higher increased proportion of P-5-CS activity and higher inhibited proportion of proDH activity under water stress compared with the drought-sensitive cultivar.  The study suggests that proline accumulation in peanut leaves under PFD can be explained by the higher enhanced activities of P-5-CS and higher inhibition of proDH.  The results will provide useful information for genetic improvement of peanut under drought tolerance.

Horticulture

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Effects of seven different companion plants on cucumber productivity, soil chemical characteristics and Pseudomonas community CHANG Chun-ling, FU Xue-peng, ZHOU Xin-gang, GUO Mei-yu, WU Feng-zhi 2017, 16(10): 2206-2214.  DOI: 10.1016/S2095-3119(17)61698-8 Abstract ( )   PDF in ScienceDirect   Companion cropping can influence cucumber productivity by altering soil chemical characteristics and microbial communities. However, how these alterations affect the growth of cucumber is still unknown. In this study, seven different plant species were selected as companion plants for testing their effects on cucumber productivity. The effects of different companion plants on changes in soil chemical properties such as electrical conductivity (EC) and contents of essential nutrients as well as the structure and abundance of the soil Pseudomonas community were evaluated. The results showed a higher cucumber yield in the wheat/cucumber companion system than that in the cucumber monocultured and other companion cropping systems. The lowest phosphorus (P) and potassium (K) contents in the soil were found in the cucumber monocultured system, and the highest NO3+-N and NH4+-N contents were observed in the rye/cucumber companion system. PCR-denaturing gradient gel electrophoresis (DGGE) and real-time PCR analysis showed that the trifolium/cucumber companion system increased the diversity of the soil Pseudomonas community, while the chrysanthemum/cucumber companion system increased its abundance. Interestingly, plant-soil feedback trials revealed that inoculating the soil of the wheat/cucumber companion system increased the growth of cucumber seedlings. In conclusion, the effects of different companion plants on cucumber productivity, soil chemical characteristics and the soil Pseudomonas community were different, and wheat was a more suitable companion plant for increasing cucumber productivity. In addition, the altered microbial community caused by companion cropping with wheat contributed to increased cucumber productivity.

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Functional characterization of MdMYB73 reveals its involvement in cold stress response in apple calli and Arabidopsis ZHANG Quan-yan, YU Jian-qiang, WANG Jia-hui, HU Da-gang, HAO Yu-jin 2017, 16(10): 2215-2221.  DOI: 10.1016/S2095-3119(17)61723-4 Abstract ( )   PDF in ScienceDirect   Recent studies have shown that the R2R3-MYB transcription factor MdMYB73 is involved in salt stress response in apple. However, no research was done whether MdMYB73 mediated cold tolerance in apple or not. In this study, we found that the expression of MdMYB73 was obviously induced by cold stress. Functional analysis showed that MdMYB73 significantly increased cold tolerance in transgenic apple calli and Arabidopsis. Quantitative real-time PCR (qRT-PCR) assay indicated that the expression levels of cold-responsive genes including MdCBF2, MdCBF3, MdCBF4, and MdCBF5 were obviously enhanced in MdMYB73 transgenic calli, suggesting that MdMYB73 increased cold tolerance via C-repeat binding factor (CBF) cold response pathway. Finally, we found that soluble sugar, which provides an osmoticum for cells, was increased in MdMYB73 transgenic calli compared to that in the wild type control. These findings provide a new insights into how MdMYB73 is involved in cold stress response.

Plant Protection

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Comparative analysis of the genome of the field isolate V86010 of the rice blast fungus Magnaporthe oryzae from Philippines ZHU Kun-peng, BAO Jian-dong, ZHANG Lian-hu, YANG Xue, LI Yuan, Zhu Ming-hui, LIN Qing-yun, ZHAO Ao, ZHAO Zhen, ZHOU Bo, LU Guo-dong 2017, 16(10): 2222-2230.  DOI: 10.1016/S2095-3119(16)61607-6 Abstract ( )   PDF in ScienceDirect   Genome dynamics of pathogenic organisms are driven by plant host and pathogenic organism co-evolution, in which pathogen genomes are used to overcome stresses imposed by hosts with various genetic backgrounds through generation of a range of field isolates.  This model also applies to the rice host and its fungal pathogen Magnaporthe oryzae.  To better understand genetic variation of M. oryzae in nature, the field isolate V86010 from the Philippines was sequenced and analyzed.  Genome annotation found that the assembled V86010 genome was composed of 1 931 scaffolds with a combined length of 38.9 Mb.  The average GC ratio is 51.3% and repetitive elements constitute 5.1% of the genome.  A total of 11 857 genes including 616 effector protein genes were predicted using a combined analysis pipeline.  All predicted genes and effector protein genes of isolate V86010 distribute on the eight chromosomes when aligned with the assembled genome of isolate 70-15.  Effector protein genes are located disproportionately at several chromosomal ends.  The Pot2 elements are abundant in V86010.  Seven V86010-specific effector proteins were found to suppress programmed cell death induced by BAX in tobacco leaves using an Agrobacterium-mediated transient assay.  Our results may provide useful information for further study of the molecular and genomic dynamics in the evolution of M. oryzae and rice host interactions, and for characterizing novel effectors and AVR genes in the rice blast pathogen.

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Functional characterization of (E)-β-caryophyllene synthase from lima bean and its up-regulation by spider mites and alamethicin LI Feng-qi, FU Ning-ning, ZHOU Jing-jiang, WANG Gui-rong 2017, 16(10): 2231-2238.  DOI: 10.1016/S2095-3119(16)61593-9 Abstract ( )   PDF in ScienceDirect   (E)-β-Caryophyllene is a sesquiterpene compound widely distributed in plants and functions in plant defence.  However, little is known about the sequence and function of (E)-β-caryophyllene synthase in lima bean (Phaseolus lunatus).  Here, we report a new full-length cDNA (PlCAHS) encoding (E)-β-caryophyllene synthase, a possible key enzyme of plant defence.  The cDNA of PlCAHS contains an open reading frame of 1 761 bp, encoding a protein of 586 amino acids with a predicted mass of 67.95 kDa.  The deduced amino acid sequence shows 52% identity with sesquiterpene synthase MtCAHS of Medicago truncatula.  Based on phylogenetic analysis, PlCAHS is classified as the terpene synthases (TPS)-a subfamily.  The recombinant enzyme, expressed in Escherichia coli, catalysed the formation of a major product (E)-β-caryophyllene (82%) and a minor product α-humulene (18%) from farnesyl diphosphate.  Real-time quantitative PCR (qRT-PCR) analysis found that the PlCAHS transcript was significantly up-regulated in leaves after treatment with spider mites and alamethicin (ALA), suggesting its ecological function in plant defence.

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Expression of mitogen-activated protein kinase double-stranded RNA in cucumber has no apparent effect on the diversity of rhizosphere archaea CHEN Guo-hua, TIAN Xue-liang, WANG Dian-dong, LING Jian, MAO Zhen-chuan, YANG Yu-hong, XIE Bing-yan 2017, 16(10): 2239-2245.  DOI: 10.1016/S2095-3119(16)61594-0 Abstract ( )   PDF in ScienceDirect   The expression of mitogen-activated protein kinase (mapk) double-stranded RNA in cucumber is effective in controlling infestations of the root-knot nematode Meloidogyne incognita.  However, little is known about the ecological effects of transgenic plants.  Here, we analyzed the diversity of 16S rDNA genes derived from the rhizosphere archaea of transgenic cucumber plants as an indicator of ecological change.  A total of 17 and 18 operational taxonomic units were detected in the rhizospheres of non-transgenic cucumber and mapk dsRNA-expressing plants, respectively.  No significant difference was observed between the two groups according to Shannon and Simpson indices.  In soil samples of the two rhizospheres, the dominant group was Crenarchaeota at the phylum level, with Staphylothermus, Methanococcus, Pyrodictium and Sulfolobus the abundant taxa at the genus level.  These results suggest that expressing mapk double-stranded (ds) RNA in cucumber has no apparent effect on the diversity of rhizosphere archaea, and provide powerful evidence for the ecological safety of transgenic cucumber expressing mapk dsRNA.

Animal Science · Veterinary Medicine

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Genetic background analysis and breed evaluation of Yiling yellow cattle Xu Ling, Zhang Wen-gang, Li Jun-ya, Zhu De-jiang, Xu Xiao-cheng, Tian Yan-zi, Xiong Xiong, Guo Ai-zhen, Cao Bing-hai, Niu Hong, Zhu Bo, Wang Ze-zhao, Liang Yong-hu, Shen Hong-xue, Chen Yan 2017, 16(10): 2246-2256.  DOI: 10.1016/S2095-3119(17)61679-4 Abstract ( )   Traditionally, Chinese indigenous cattle is geographically widespread.  The present study analyzed based on genome-wide variants to evaluate the genetic background among 157 individuals from four representative indigenous cattle breeds of Hubei Province of China: Yiling yellow cattle (YL), Bashan cattle (BS), Wuling cattle (WL), Zaobei cattle (ZB), and 21 individuals of Qinchuan cattle (QC) from the nearby Shanxi Province of China.  Linkage disequilibrium (LD) analysis showed the LD of YL was the lowest (r2=0.32) when the distance between markers was approximately 2 kb.  Principle component analysis (PCA), and neighbor-joining (NJ)-tree revealed a separation of Yiling yellow cattle from other geographic nearby local cattle breeds.  In PCA plot, the YL and QC groups were segregated as expected; moreover, YL individuals clustered  together more obviously.  In the NJ-tree, the YL group formed an independent branch and BS, WL, ZB groups were mixed.  We then used the FST statistic approach to reveal long-term selection sweep of YL and other 4 cattle breeds.  According to the selective sweep, we identified the unique pathways of YL, associated with production traits.  Based on the results, it can be proposed that YL has its unique genetic characteristics of excellence resource, and it is an indispensable cattle breed in China.

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Research on the appropriate way to transfer exogenous substances into chicken embryos WANG Yi-lin, JIN Kai, HE Na-na, CHENG Shao-ze, ZUO Qi-sheng, LI Dong, WANG Ying-jie, WANG Fei, JI Yan-qing, LU Zhen-yu, ZHANG Chen, WANG Man, ZHAO Rui-feng, YU Xin-jian, ZHANG Ya-ni, ZHAO Wen-ming... 2017, 16(10): 2257-2263.  DOI: 10.1016/S2095-3119(17)61668-X Abstract ( )   PDF in ScienceDirect   In biological research, chicken embryos are a classic experimental model for the exploration of the embryonic development and cell differentiation.  Transferring exogenous substances into chicken embryos for producing medical antibodies has been widely used in the production practice.  However, there are few studies about the effect of the different injection site and dosage on chicken embryos.  The aim of this study was to explore the effects of different injection sites and dosages on chicken embryo hatching rate and development, so as to provide a basis for further studies using the chicken embryo model.  Freshly laid eggs (Rugao yellow chicken) were injected with different doses of saline at the tip, equatorial plane and the blunt end of the egg shell, respectively.  Egg hatching rate was recorded and compared among injection sites and different doses.  A trypan blue stain was also injected at the aforementioned sites and the growth of chicken embryos was observed.  The SPSS (statistical package for the social science) software was used to analyze the relationship between the chicken eggs hatching rate and the different injection sites or the different dosages.  The experimental results showed that there were significant differences on egg hatching rates among the different injection sites and doses (P<0.05).  The hatchability of the blunt end injection group was significantly higher than that of the other two sites.  The egg hatching rate decreased with increased saline doses.  The egg hatching rate of the 100 µL saline injection group was higher than the 200 and 300 µL dosage groups.  Ultimately, we suggest that the optimal chicken embryo injection process is during early development, at the blunt end site with a dose less than 100 µL to minimize damage to the egg.

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Newcastle disease virus-based MERS-CoV candidate vaccine elicits high-level and lasting neutralizing antibodies in Bactrian camels Liu Ren-qiang, Ge Jin-ying, Wang Jin-ling, Shao Yu, Zhang Hui-lei, Wang Jin-liang, Wen Zhi-yuan, Bu Zhi-gao 2017, 16(10): 2264-2273.  DOI: 10.1016/S2095-3119(17)61660-5 Abstract ( )   PDF in ScienceDirect   Middle East respiratory syndrome coronavirus (MERS-CoV), a member of the Coronaviridae family, is the causative pathogen for MERS that is characterized by high fever, pneumonia, acute respiratory distress syndrome (ARDS), as well as extrapulmonary manifestations.  Currently, there are no approved treatment regimens or vaccines for MERS.  Here, we generated recombinant nonvirulent Newcastle disease virus (NDV) LaSota strain expressing MERS-CoV S protein (designated as rLa-MERS-S), and evaluated its immunogenicity in mice and Bactrian camels.  The results revealed that rLa-MERS-S showed similar growth properties to those of LaSota in embryonated chicken eggs, while animal immunization studies showed that rLa-MERS-S induced MERS-CoV neutralizing antibodies in mice and camels.  Our findings suggest that recombinant rLa-MERS-S may be a potential MERS-CoV veterinary vaccine candidate for camels and other animals affected by MERS.

Agro-Ecosystem & Environment

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Rice cultivation changes and its relationships with geographical factors in Heilongjiang Province, China LU Zhong-jun, SONG Qian, LIU Ke-bao, WU Wen-bin, LIU Yan-xia, XIN Rui, ZHANG Dong-mei 2017, 16(10): 2274-2282.  DOI: 10.1016/S2095-3119(17)61705-2 Abstract ( )   PDF in ScienceDirect   Rice planting patterns have changed dramatically over the past several decades in northeast China (NEC) due to the combined influence of global change and agricultural policy.  Except for its great implications for environmental protection and climate change adaption, the spatio-temporal changes of rice cultivation in NEC are not clear.  In this study, we conducted spatio-temporal analyses of NEC’s major rice production region, Heilongjiang Province, by using satellite-derived rice cultivation maps.  We found that the total cultivated area of rice in Heilongjiang Province increased largely from 1993 to 2011 and it expanded spatially to the northern and eastern part of the Sanjiang Plain.  The results also showed that rice cultivation areas experienced a larger increase in the region managed by the Reclamation Management Bureau (RMB) than that managed by the local provincial government.  Rice cultivation changes were closely related with those geographic factors over the investigated periods, represented by the geomorphic (slope), climatic (accumulated temperature), and hydrological (watershed) variables.  These findings provide clear evidence that crop cultivation in NEC has been modified to better cope with the global change.

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Assimilation of temporal-spatial leaf area index into the CERES-Wheat model with ensemble Kalman filter and uncertainty assessment for improving winter wheat yield estimation LI He, JIANG Zhi-wei, CHEN Zhong-xin, REN Jian-qiang, LIU Bin, Hasituya 2017, 16(10): 2283-2299.  DOI: 10.1016/S2095-3119(16)61351-5 Abstract ( )   PDF in ScienceDirect   To accurately estimate winter wheat yields and analyze the uncertainty in crop model data assimilations, winter wheat yield estimates were obtained by assimilating measured or remotely sensed leaf area index (LAI) values.  The performances of the calibrated crop environment resource synthesis for wheat (CERES-Wheat) model for two different assimilation scenarios were compared by employing ensemble Kalman filter (EnKF)-based strategies.  The uncertainty factors of the crop model data assimilation was analyzed by considering the observation errors, assimilation stages and temporal-spatial scales.  Overall, the results indicated a better yield estimate performance when the EnKF-based strategy was used to comprehensively consider several factors in the initial conditions and observations.  When using this strategy, an adjusted coefficients of determination (R2) of 0.84, a root mean square error (RMSE) of 323 kg ha–1, and a relative errors (RE) of 4.15% were obtained at the field plot scale and an R2 of 0.81, an RMSE of 362 kg ha–1, and an RE of 4.52% were obtained at the pixel scale of 30 m×30 m.  With increasing observation errors, the accuracy of the yield estimates obviously decreased, but an acceptable estimate was observed when the observation errors were within 20%.  Winter wheat yield estimates could be improved significantly by assimilating observations from the middle to the end of the crop growing seasons.  With decreasing assimilation frequency and pixel resolution, the accuracy of the crop yield estimates decreased; however, the computation time decreased.  It is important to consider reasonable temporal-spatial scales and assimilation stages to obtain tradeoffs between accuracy and computation time, especially in operational systems used for regional crop yield estimates.

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Using the DSSAT model to simulate wheat yield and soil organic carbon under a wheat-maize cropping system in the North China Plain LIU Hai-long, LIU Hong-bin,LEI Qiu-liang, ZHAI Li-mei, WANG Hong-yuan, ZHANG Ji-zong, ZHU Yeping, LIU Sheng-ping, LI Shi-juan, ZHANG Jing-suo, LIU Xiao-xia 2017, 16(10): 2300-2307.  DOI: 10.1016/S2095-3119(17)61678-2 Abstract ( )   PDF in ScienceDirect   Crop modelling can facilitate researchers’ ability to understand and interpret experimental results, and to diagnose yield gaps. In this paper, the Decision Support Systems for Agrotechnology Transfer 4.6 (DSSAT) model together with the CENTURT soil model were employed to investigate the effect of low nitrogen (N) input on wheat (Triticum aestivum L.) yield, grain N concentration and soil organic carbon (SOC) in a long-term experiment (19 years) under a wheat-maize (Zea mays L.) rotation at Changping, Beijing, China.  There were two treatments including N0 (no N application) and N150 (150 kg N ha–1) before wheat and maize planting, with phosphorus (P) and potassium (K) basal fertilizers applied as 75 kg P2O5 ha–1 and 37.5 kg K2O ha–1, respectively.  The DSSAT-CENTURY model was able to satisfactorily simulate measured wheat grain yield and grain N concentration at N0, but could not simulate these parameters at N150, or SOC in either N treatment.  Model simulation and field measurement showed that N application (N150) increased wheat yield compared to no N application (N0).  The results indicated that inorganic fertilizer application at the rates used did not maintain crop yield and SOC levels.  It is suggested that if the DSSAT is calibrated carefully, it can be a useful tool for assessing and predicting wheat yield, grain N concentration, and SOC trends under wheat-maize cropping systems.

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Spatiotemporal variation of drought characteristics in the Huang-Huai-Hai Plain, China under the climate change scenario LI Xiang-xiang, JU Hui, Sarah Garré, YAN Chang-rong, William D. Batchelor, LIU Qin 2017, 16(10): 2308-2322.  DOI: 10.1016/S2095-3119(16)61545-9 Abstract ( )   PDF in ScienceDirect   Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain (3H Plain), which is a major grain production area in China.  In this paper, we investigated the variations in drought characteristics (drought event frequency, duration, severity, and intensity) for the past 50 years (1961–2010) and under future scenarios (2010–2099), based on the observed meteorological data and the Representative Concentration Pathway (RCP) 8.5 scenario, respectively.  First, we compared the applicability of three climatic drought indices: the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index based on the Penman-Monteith equation (SPEI-PM) and the same index based on the Thornthwaite equation (SPEI-TH) to correlate the recorded agricultural drought areas.  Then, we analyzed the drought characteristics using ‘run theory’ for both historical and the future RCP 8.5 scenario based on the best performing index.  Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain.  Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961–2010 showed an decreasing trend.  However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010–2099, although drought components during the 2010–2039 are predicted to be milder compared with historical conditions.  This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices.  The results of this study can help inform researchers and local policy makers to establish drought management strategies.

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Modeling the regional grazing impact on vegetation carbon sequestration ability in Temperate Eurasian Steppe CHEN Yi-zhao, SUN Zheng-guo, QIN Zhi-hao, Pavel Propastin, WANG Wei, LI Jian-long, RUAN Hong-hua 2017, 16(10): 2323-2336.  DOI: 10.1016/S2095-3119(16)61614-3 Abstract ( )   PDF in ScienceDirect   Anthropogenic activities profoundly influence carbon sequestration in the Eurasian Steppe.  In particular, grazing has been identified as having a major effect on carbon sequestration.  However, the extent to which grazing affects regional patterns or carbon sequestration is unknown.  In this study, we evaluated the impact of regional grazing on grassland carbon sequestration using the Boreal Ecosystem Productivity Simulator (BEPS) and the Shiyomi grazing model.  Model performances were validated against the results from field measurements and eddy covariance (EC) sites.  Model outputs showed that in 2008, the regional net primary productivity (NPP) was 79.5 g C m–2, and the net ecosystem productivity (NEP) was –6.5 g C m–2, characterizing the region as a weak carbon source.  The Mongol Steppe (MS) was identified as a carbon sink, whereas the Kazakh Steppe (KS) was either carbon neutral or a weak carbon source.  The spatial patterns of grazing density are divergent between the MS and the KS.  In the MS, livestock was mainly distributed in China with relatively good management, while in the KS livestock was mainly concentrated in the southern countries (especially Uzbekistan and Turkmenistan) with harsh environments and poor management.  The consumption percentages of NPP in Turkmenistan, Tajikistan and Uzbekistan were 5.3, 3.3 and 1.2%, respectively, whereas the percentages in other countries were lower than 1%.  Correspondingly, grazing consumption contributed to the carbon sources of Turkmenistan, Tajikistan and Uzbekistan by 11.6, 6.3 and 4.3%, respectively, while it weakened the carbon sink in Inner Mongolia, China and Mongolia by 1.6 and 0.5%.  This regional pattern should be affected by different sub-regional characteristics, e.g., the continuous degradation of grassland in the southern part of the KS and the restoration of grassland in Inner Mongolia, China.

Agricultural Economics and Management

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Rice variety improvement and the contribution of foreign germplasms in China SHI Xiao-hua, HU Rui-fa 2017, 16(10): 2337-2345.  DOI: 10.1016/S2095-3119(16)61615-5 Abstract ( )   PDF in ScienceDirect   The introduction and use of foreign germplasms have played an important role in the improvement of crop varieties in China.  Based on published materials and scientist interviews, we collected data on the sown area, morphological characteristics, and pedigree of the popular rice varieties grown in the 15 major rice production provinces and 1 autonomous region in China, from 1982 to 2011.  Results showed that China’s scientists developed the largest number of rice varieties worldwide, and that rice yield potential and grain quality have substantiality improved during the studied period.  In contrast, resistance of newly-released varieties to diseases and insect pests has decreased since the 1990s.  Germplasms from the International Rice Research Institute (IRRI) and from Japan have contributed 16.4 and 11.2% of genetic materials to China’s rice varieties developed between 1982 and 2011, respectively.  While IRRI’s materials contributed to the improvement of yield potential, growth duration, and blast and bacterial blight resistance, Japanese materials contributed to the improvement of grain quality.  Materials from other countries contributed to the improvement of resistance to diseases and insect pests, particularly to rice blast disease, brown planthoppers, white-backed planthoppers, and striped stem borers.

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The impact of Bt cotton adoption on the stability of pesticide use QIAO Fang-bin, HUANG Ji-kun, WANG Shu-kun, LI Qiang 2017, 16(10): 2346-2356.  DOI: 10.1016/S2095-3119(17)61699-X Abstract ( )   PDF in ScienceDirect   Even though the impact of Bacillus thuringiensis (Bt) cotton on pesticide use has been well documented, all previous studies focus on the mean value of pesticide use.  Using seven unique waves of panel data collected between 1999 and 2012 in China, we show that Bt cotton adoption has not only caused a reduction of the mean value of pesticide use, but also a reduction of the standard deviation of pesticide use.  We conclude that Bt technology adoption has also contributed to the stability of pesticide use in cotton production.  We believe that this contribution is theoretically and practically relevant because of the long length of our unique dataset.