2019 Vol. 18 No. 10 Previous Issue    Next Issue

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

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    Crop Science
    Application of virus-induced gene silencing for identification of FHB resistant genes
    FAN Yan-hui, HOU Bing-qian, SU Pei-sen, WU Hong-yan, WANG Gui-ping, KONG Ling-rang, MA Xin, WANG Hong-wei
    2019, 18(10): 2183-2192.  DOI: 10.1016/S2095-3119(18)62118-5
    Abstract ( )   PDF in ScienceDirect  
    Virus-induced gene silencing (VIGS) showed several advantages to identify gene functions such as short experimental cycle, more broad hosts, etc.  In this study, the feasibility and efficiency of employing Barley stripe mosaic virus (BSMV)-based VIGS system to evaluate Fusarium head blight (FHB) resistance were explored in wheat.  With variable conditions tested, it showed that the maximal silencing efficiency 78% on spike was obtained when the recombinant BSMV was inoculated on flag leaf at flagging stage.  However, the plant may reduce its own immunity to FHB when inoculated with BSMV.  To induce this impact, different Fusarium graminearum strains were tested and SF06-1 strain was selected for FHB resistance evaluation.  Using this system, TaAOC, TaAOS, and TaOPR3 involved in jasmonic acid (JA) signaling pathway were identified to positively regulate FHB resistance, which was underpinned by the results when silencing TaAOS in wheat by stable transgenic plants.
    Dynamic changes of root proteome reveal diverse responsive proteins in maize subjected to cadmium stress
    REN Wen, LIU Ya, ZHOU Miao-yi, SHI Zi, WANG Tian-yu, ZHAO Jiu-ran, LI Yu
    2019, 18(10): 2193-2204.  DOI: 10.1016/S2095-3119(18)62140-9
    Abstract ( )   PDF in ScienceDirect  
    Toxic symptoms and tolerance mechanisms of heavy metal in maize are well documented.  However, limited information is available regarding the changes in the proteome of maize seedling roots in response to cadmium (Cd) stress.  Here, we employed an iTRAQ-based quantitative proteomic approach to characterize the dynamic alterations in the root proteome during early developmental in maize seedling.  We conducted our proteomic experiments in three-day seedling subjected to Cd stress, using roots in four time points.  We identified a total of 733, 307, 499, and 576 differentially abundant proteins after 12, 24, 48, or 72 h of treatment, respectively.  These proteins displayed different functions, such as ribosomal synthesis, reactive oxygen species homeostasis, cell wall organization, cellular metabolism, and carbohydrate and energy metabolism.  Of the 166 and 177 proteins with higher and lower abundance identified in at least two time points, 14 were common for three time points.  We selected nine proteins to verify their expression using quantitative real-time PCR.  Proteins involved in the ribosome pathway were especially responsive to Cd stress.  Functional characterization of the proteins and the pathways identified in this study could help our understanding of the complicated molecular mechanism involved in Cd stress responses and create a list of candidate gene responsible for Cd tolerance in maize seeding roots.
    Strategies to enhance cottonseed oil contents and reshape fatty acid profile employing different breeding and genetic engineering approaches
    Iram Sharif, Jehanzeb Farooq, Shahid Munir Chohan, Sadaf Saleem, Riaz Ahmad Kainth, Abid Mahmood, Ghulam Sarwar
    2019, 18(10): 2205-2218.  DOI: 10.1016/S2095-3119(18)62139-2
    Abstract ( )   PDF in ScienceDirect  
    Cottonseed oil is the valuable byproduct extracted after seed cotton processing for lint.  It confers a huge contribution to total vegetable oil production and ranked the 2nd to meet global edible oil requirements.  Over centuries, breeders mainly focused to improve lint production and fiber quality.  Now attention has been given to improve the cottonseed oil percentage, its functional and nutritional properties.  However, these efforts are less than other major oilseed crops which left cottonseed oil market behind in term of consumer demand and kept cottonseed oil industry at vulnerable position.  Considerable progress has been made to alter the relative percentage of fatty acid composition still intensified efforts have been required to meet the global oilseed demand.  The objective of this review is to explore the cotton germplasm variation for seed oil carrying potential, its utilization in suitable breeding programs, seed oil biosynthetic pathways, major genes, and QTLs linked to quantity and quality enhancement of oil and deployment of modern genomic tools, viz., gene silencing and transgenic development to ameliorate its nutritional properties.  
    Maize/peanut intercropping increases photosynthetic characteristics, 13C-photosynthate distribution, and grain yield of summer maize
    LI Yan-hong, SHI De-yang, LI Guang-hao, ZHAO Bin, ZHANG Ji-wang, LIU Peng, REN Bai-zhao, DONG Shu-ting
    2019, 18(10): 2219-2229.  DOI: 10.1016/S2095-3119(19)62616-X
    Abstract ( )   PDF in ScienceDirect  
    Intercropping is used widely by smallholder farmers in developing countries to increase land productivity and profitability.  We conducted a maize/peanut intercropping experiment in the 2015 and 2016 growing seasons in Shandong, China.  Treatments included sole maize (SM), sole peanut (SP), and an intercrop consisting of four rows of maize and six rows of peanut (IM and IP).  The results showed that the intercropping system had yield advantages based on the land equivalent ratio (LER) values of 1.15 and 1.16 in the two years, respectively.  Averaged over the two years, the yield of maize in the intercropping was increased by 61.05% compared to that in SM, while the pod yield of peanut was decreased by 31.80% compared to SP.  Maize was the superior competitor when intercropped with peanut, and its productivity dominated the yield of the intercropping system in our study.  The increased yield was due to a higher kernel number per ear (KNE).  Intercropping increased the light transmission ratio (LTR) of the ear layer in the maize canopy, the active photosynthetic duration (APD), and the harvest index (HI) compared to SM.  In addition, intercropping promoted the ratio of dry matter accumulation after silking and the distribution of 13C-photosynthates to grain compared to SM.  In conclusion, maize/peanut intercropping demonstrated the potential to improve the light condition of maize, achieving enhanced photosynthetic characteristics that improved female spike differentiation, reduced barrenness, and increased KNE.  Moreover, dry matter accumulation and 13C-photosynthates distribution to grain of intercropped maize were improved, and a higher grain yield was ultimately obtained.
    Rhizosphere soil bacterial community composition in soybean genotypes and feedback to soil P availability
    ZHOU Tao, WANG Li, DU Yong-li, LIU Ting, LI Shu-xian, GAO Yang, LIU Wei-guo, YANG Wen-yu
    2019, 18(10): 2230-2241.  DOI: 10.1016/S2095-3119(18)62115-X
    Abstract ( )   PDF in ScienceDirect  
    Soil with low phosphorus (P) availability and organic matter contents exists in large area of southwest of China, but some soybean genotypes still show well adaptations to this low yield farmland.  However, to date, the underlying mechanisms of how soybean regulates soil P availability still remains unclear, like microbe-induced changes.  The objective of the present study was to compare the differences of rhizosphere bacterial community composition between E311 and E109 in P-sufficiency (10.2 mg kg–1) and P-insufficiency (5.5 mg kg–1), respectively, which then feedback to soil P availability.  In P-sufficiency, significant differences of the bacterial community composition were observed, with fast-growth bacterial phylum Proteobacteria, genus Dechloromonas, Pseudomonas, Massilia, and Propionibacterium that showed greater relative abundances in E311 compared to E109, while in P-insufficiency were not.  A similar result was obtained  that E311 and E109 were clustered together in P-insufficiency rather than in P-sufficiency by using principal component analysis and hierarchical clustering analysis.  The quadratic relationships between bacterial diversity and soil P availability in rhizosphere were analyzed, confirming that bacterial diversity enhanced the soil P availability.  Moreover, the high abundance of Pseudomonas and Massilia in the rhizosphere of E311 might increased the P availability.  In the present study, the soybean E311 showed capability of shaping rhizosphere bacterial diversity, and subsequently, increasing soil P availability.  This study provided a strategy for rhizosphere management through soybean genotype selection and breeding to increase P use efficiency, or upgrade middle or low yield farmland.
    Effect of biochar on grain yield and leaf photosynthetic physiology of soybean cultivars with different phosphorus efficiencies
    ZHU Qian, KONG Ling-jian, SHAN Yu-zi, YAO Xing-dong, ZHANG Hui-jun, XIE Fu-ti, AO Xue
    2019, 18(10): 2242-2254.  DOI: 10.1016/S2095-3119(19)62563-3
    Abstract ( )   PDF in ScienceDirect  
    This study was conducted with two soybean cultivars, Liaodou 13 (L13, phosphorus (P)-efficient) and Tiefeng 3 (T3, P-inefficient), to investigate the effects of biochar on soybean yield and photosynthetic physiological parameters, at four biochar application rates (0, 1, 5, and 10%, w/w), and two fertilization treatments (0 and 150 kg ha–1).  Grain yield, plant biomass, P accumulation, leaf net photosynthetic rate (Pn), chlorophyll index (Chl), nitrogen balance index (NBI), sucrose phosphate synthase (SPS), and sucrose synthase (SS) activities, soluble sugar, sucrose and starch contents, and leaf area duration (LAD) were measured.  Biochar had positive effects on Pn, Chl, NBI, SPS, and SS activities, and leaf soluble sugar, sucrose, and starch contents of both genotypes, these effects increased with biochar application rate.  L13 benefited more efficiently from biochar than T3 did, as the grain yield of L13 significantly increased by 31.0 and 51.0%, at 5 and 10% biochar, respectively, while that of T3 increased by 40.4 at 10% biochar application rate, as compared with controls.  The combined application of biochar and fertilizer boosted the positive effects described, but no difference was found for grain yield in L13 among biochar application rates, while grain yield of T3 continually increased with biochar rate, among which, 1% biochar combined with 150 kg ha–1 fertilizer resulted in T3 yield increment of more than 23%, compared with the application of 150 kg ha–1 fertilizer alone.  Altogether, our results indicated that the application of biochar enhanced carbon assimilation in soybean, resulting in increased biomass accumulation and yield.  Differences in genotypic responses to biochar highlight the need to consider specific cultivars and biochar rate, when evaluating the potential responses of crops to biochar.
    Inheritance of steroidal glycoalkaloids in potato tuber flesh
    PENG Zhen, WANG Pei, TANG Die, SHANG Yi, LI Can-hui, HUANG San-wen, ZHANG Chun-zhi
    2019, 18(10): 2255-2263.  DOI: 10.1016/S2095-3119(19)62718-8
    Abstract ( )   PDF in ScienceDirect  
    Potato (Solanum tuberosum L.) is the third most important food crop worldwide after wheat and rice in terms of human consumption.  A critical domestication trait for potato was the decrease of toxic steroidal glycoalkaloids (SGAs) in tuber flesh.  Here, we used a diploid F2 segregating population derived from a cross between S. tuberosum and the wild potato species Solanum chacoense to map the quantitative trait loci (QTLs) associated with the regulation of SGAs content in tuber flesh.  In a three-year study, we identified two QTLs on chromosomes 2 and 8 affecting SGAs content in tuber flesh.  The QTL on chromosome 8 harbors 38 genes that are co-expressed with the GLYCOALKALOID METABOLISM genes.  These findings lay the foundation for exploiting the genes controlling SGAs content in tuber flesh and they provide a theoretical basis for the use of wild germplasm in potato breeding.
    Transcriptome analysis reveals the effects of alkali stress on root system architecture and endogenous hormones in apple rootstocks
    LIU Xuan, LIANG Wei, LI Yu-xing, LI Ming-jun, MA Bai-quan, LIU Chang-hai, MA Feng-wang, LI Cui-ying
    2019, 18(10): 2264-2271.  DOI: 10.1016/S2095-3119(19)62706-1
    Abstract ( )   PDF in ScienceDirect  
    Soil alkalinity is a major factor that restricts the growth of apple roots. To analyze the response of apple roots to alkali stress, the root structure and endogenous hormones of two apple rootstocks, Malus prunifolia (alkali-tolerant) and Malus hupehensis (alkali-sensitive), were compared. To understand alkali tolerance of M. prunifolia at the molecular level, transcriptome analysis was performed. When plants were cultured in alkaline conditions for 15 d, the root growth of M. hupehensis with weak alkali tolerance decreased significantly. Analysis of endogenous hormone levels showed that the concentrations of indole-3-acetic acid (IAA) and zeatin riboside (ZR) in M. hupehensis under alkali stress were lower than those in the control. However, the trend for IAA and ZR in M. prunifolia was the opposite. The concentration of abscisic acid (ABA) in the roots of the two apple rootstocks under alkali stress increased, but the concentration of ABA in the roots of M. prunifolia was higher than that in M. hupehensis. The expression of IAA-related genes ARF5, GH3.6, SAUR36, and SAUR32 and the Cytokinin (CTK)-related gene IPT5 in M. prunifolia was higher than those in the control, but the expression of these genes in M. hupehensis was lower than those in the control. The expression of ABA-related genes CIPK1 and AHK1 increased in the two apple rootstocks under alkali stress, but the expression of CIPK1 and AHK1 in M. prunifolia was higher than in M. hupehensis. These results demonstrated that under alkali stress, the increase of IAA, ZR, and ABA in roots and the increase of the expression of related genes promoted the growth of roots and improved the alkali tolerance of apple rootstocks.
    Postharvest responses of hydroponically grown lettuce varieties to nitrogen application rate
    Bevly M. Mampholo, Martin Maboko, Puffy Soundy, Dharini Sivakumar
    2019, 18(10): 2272-2283.  DOI: 10.1016/S2095-3119(19)62664-X
    Abstract ( )   PDF in ScienceDirect  

    Limited information is available on the influence of preharvest N application rates on postharvest quality of different lettuce genotypes.  Two green leafy lettuce (Multigreen 1 and Multigreen 3) and red leafy lettuce (Multired 4) were grown in gravel film technique and fertigated with five different N application rates: 60, 90, 120, 150 and 180 mg L–1.  The 120 mg L–1 N application is commercially recommended for lettuce.  After harvest, lettuce samples were packed in a bioriented poly propylene packaging (5% O2 and 5% CO2) and  held at 5°C and 85% RH for 3, 6, 9 and 12 days.  The genotypes, preharvest N application rates and storage time affected the leaf colour coordinates, phenolic acids (dicaffeoyltataric acid, caffeoyl tartaric acid, 3-caffeoylquinic acid and 3,4-dihydroxycinnamic acid) and browning enzyme activities (phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD)).  Lower rates of N application at preharvest stage showed higher weight loss with the storage time increasing in Multigreen 3.  In Multigreen 1, colour coordinate b* value decreased remarkably with N application rates from 60 to 120 mg L–1 due to the onset of browning during storage.  While in Multigreen 3 and N application higher than 60 mg L–1 influenced the decrease in b* value.  Browning occurred due to the increased activity of PAL enzyme and the availability of the substrates caftaric, chlorogenic, caffeic acids, PPO activity and production of browning pigments due to the activity of POD.  Higher, N application rates (>120 mg L–1) influenced the browning mechanism and showed brownish red leaves in Multired 4 during storage.  Higher ascorbic acid concentration played a role in reducing the onset of browning in the fresh cuts leaves of Mulitired 4 and Multigreen 3 fertilized with lower preharvest lower N application rates (<120 mg L–1).  Preharvest N application at 90 mg L–1 retained the colour, ascorbic acid content and the phenolic acid components and extended the shelf life of Multired 4 lettuce up to 6 days. 

    Plant Protection
    Limited infection by ‘Candidatus Liberibacter asiaticus’ in ‘Valencia’ sweet orange trees in the presence of Citrus tristeza virus
    FU Shi-min, Cristina Gouin, ZHOU Chang-yong, John S. Hartung
    2019, 18(10): 2284-2293.  DOI: 10.1016/S2095-3119(19)62605-5
    Abstract ( )   PDF in ScienceDirect  
    Huanglongbing (HLB) is the most destructive disease of citrus and is associated with ‘Candidatus Liberibacter asiaticus’ (CLas), a member of the α-proteobacteria. Citrus tristeza virus (CTV) is another pathogen of citrus with very great historic as well as current importance. Both CLas and CTV are phloem-restricted pathogens. A severe CTV isolate, CTV-B6, and CLas-B232 induce a group of symptoms of phloem dysfunction that overlap, but the mild isolate CTV-B2 does not cause any loss to commercial trees. Prior inoculation and establishment of CLas-B232 did not affect subsequent establishment of either CTV-B2 or CTV-B6, while super infection by CLas-B232 was reduced by prior establishment of CTV-B2 and to a lesser extent by prior infection with CTV-B6. Trees co-infected with CTV-B6 and CLas-B232 developed more severe symptoms, typical of CTV-B6, than either of the two pathogens co-infected with CTV-B2. In this study, we confirmed that CLas established in the rootlets earlier and with higher concentration than in leaves. The distribution of CLas in the plant infected by CLas-B438 alone and with CTV-B2 fits a previously proposed model but CLas was more sporadically distributed in a plant co-infected by CLas and CTV-B2 than in a plant infected by CLas alone. These biological phenomena are aligned with previously analyzed transcriptome data and the study provides a novel idea that mild CTV strains may provide some protection against CLas by limiting its multiplication and spread. The protective effect may be due to opposite regulation of key host defense pathways in response to CTV-B2 and CLas-B438.
    Sugarcane mosaic virus infection of model plants Brachypodium distachyon and Nicotiana benthamiana
    XU Jing-sheng, DENG Yu-qing, CHENG Guang-yuan, ZHAI Yu-shan, PENG Lei, DONG Meng, XU Qian, YANG Yong-qing
    2019, 18(10): 2294-2301.  DOI: 10.1016/S2095-3119(19)62572-4
    Abstract ( )   PDF in ScienceDirect  
    Sugarcane mosaic virus (SCMV; genus Potyvirus, family Potyviridae) is a causal pathogen of sugarcane mosaic disease, and it is widespread in regions where sugarcane (Saccharum spp. hybrids) is grown.  It is difficult to investigate the molecular mechanism of pathogen infection in sugarcane because of limited genomic information.  Here, we demonstrated that SCMV strain FZ1 can systemically infect Brachypodium distachyon inbred line Bd21 and Nicotiana benthamiana through inoculation, double antibody sandwich enzyme-linked immunosorbent, transmission electron microscopy, and reverse transcription PCR assays.  The leaves of Bd21 developed mosaic symptoms, while the leaves of N. benthamiana showed no obvious symptoms under the challenge of SCMV-FZ1.  We concluded that B. distachyon inbred line Bd21 is a promising experimental model plant compared with N. benthamiana for study on the infectivity of SCMV.  This is the first report on the SCMV infection of model plants B. distachyon inbred line Bd21 and N. benthamiana, which will shed light on the mechanism of SCMV infection of sugarcane and benefit sugarcane breeding against sugarcane mosaic disease.
    Quantitative analysis of the interaction of heterologous viruses with Plum pox virus in C5 HoneySweet transgenic plums
    Khushwant Singh, Tereza Neubauerová, Jiban Kumar Kundu
    2019, 18(10): 2302-2310.  DOI: 10.1016/S2095-3119(18)62136-7
    Abstract ( )   PDF in ScienceDirect  
    Stone fruits are an important crop in most parts of the world and are heavily challenged by several viruses including Plum pox virus (PPV), Prune dwarf virus (PDV), Prunus necrotic ringspot virus (PNRSV), and Apple chlorotic leaf spot virus (ACLSV).  We validated the PPV resistance in C5 plum plants (commercially known as HoneySweet) grown in the Czech Republic for more than 16 years in a field trial experiment under natural environmental conditions.  We quantified single (PPV-Rec) and mixed viruses (PPV-Rec+ACLSV, PPV-Rec+PDV and PPV-Rec+ACLSV+PDV) in C5 transgenic plums inoculated for the period 2016 to 2018.  The accumulation of PPV-Rec was high (~5.43E+05 copies) compared with that of ACLSV (~8.70E+04 copies) in the inoculated graft of C5 transgenic plants.  Leaves close to the inoculum sources showed a differential level of virus titre in single and mixed infections (~10 to ~5×102 copies).  C5 plants with permanent virus pressure showed 103- to 105-fold fewer copies of viruses than those of the inoculated graft.  We observed high accumulation of conserved miRNAs such as miR167, miR69 and miR396 in C5 plants co-infected with PPV, ACLSV and PDV that are associated with its resistance against viruses.  Overall, i) C5 transgenic plums showed high resistance to PPV infection, and a low level (~32 copies) of PPV only accumulated in some grafted plants, ii) high accumulation of PPV was found in inoculated grafts in single PPV infection and mixed infections, iii) heterologous virus infection sustained by ACLSV or PDV did not suppress PPV resistance, and iv) high and low conserved microRNAs accumulated in C5 plants.
    Molecular cloning, expression profiling and RNA interference of a vitellogenin gene from Harmonia axyridis (Coleoptera: Coccinellidae)
    LIANG Chao, LIU Ting-hui, HAN Shi-peng, HE Yun-zhuan
    2019, 18(10): 2311-2320.  DOI: 10.1016/S2095-3119(18)62103-3
    Abstract ( )   PDF in ScienceDirect  
    In this study, the Harmonia axyridis vitellogenin gene 2 (HmVg2) sequence was identified from transcriptomic databases of female adult H. axyridis and cloned into pMD18-T vector.  The HmVg2 gene was 5 460 bp in length, and formed with an open reading frame (ORF) of 5 361 nucleotides (GenBank accession no. KY794939).  The putative molecular weight of the primary HmVg2 protein was 203.459 kDa and the predicted isoelectric point (pI) was 8.59.  HmVg2 contained a signal peptide, vitellogenin N-terminal (vitellogenin-N) domain, domain of unknown function 1943 (DUF1934) domain and von Willebrand factor type D (VWD) domain.  The developmental expression profiling showed that HmVg2 was extremely highly expressed in female insects, but was expressed at lower levels in male insects.  In female insects, HmVg2 was mainly expressed in the wing and fat body.  The double-stranded RNA-HmVg2/-GFP was injected into H. axyridis, and qRT-PCR results showed that the HmVg2 gene was specifically silenced.  The eggs laid during the first five days and the hatching rate of eggs was lower than controls after dsHmVg2 injection.  This investigation demonstrated that the HmVg2 gene plays an important role in H. axyridis reproduction and enriches the function of the insect vitellogenin gene.
    More stressful event does not always depress subsequent life performance
    CHEN Ying-ying, ZHANG Wei, MA Gang, MA Chun-sen
    2019, 18(10): 2321-2329.  DOI: 10.1016/S2095-3119(18)62145-8
    Abstract ( )   PDF in ScienceDirect  
    Climate change has led to a substantial increase in intensity and duration of heat waves worldwide.  Predicting the ecological impacts of hot events should incorporate both immediate and potential carry-over effects in different intensities of heat waves.  Previous studies suggested that higher heat dose in early life stage of insect generally decreased immediate survival and depressed adult reproduction through carry-over effects, or unchanged adult performance through recovery effects.  However, our previous study showed a different pattern, in which longer heat exposures in larval stage did not always decrease but sometimes increase the subsequent adult maturation success in the diamondback moth.  We speculated that it might be another important pattern in the carry-over effects vs. heat dose, and conducted experiments using a global pest, Plutella xylostella.  Our present results suggested that heat exposures in early life stage reduced the immediate survival and produced general declines with significant zigzag fluctuating patterns in subsequent body size and reproduction as exposure durations increased.  The similar patterns were also validated in other insect taxa and other stresses by reanalyzing the experiment data from literatures.  The finding highlights the importance for differentiating the biological effects and consequences of changes in heat dose at fine scales; daily exposure hours of a hot day should be considered to predict population dynamic under climate change.
    Flight behavior of the sycamore lace bug, Corythucha ciliata, in relation to temperature, age, and sex
    LU Shao-hui, WEI Mei-cai, YUAN Guo-jun, CUI Jian-xin, GONG Dong-feng
    2019, 18(10): 2330-2337.  DOI: 10.1016/S2095-3119(19)62624-9
    Abstract ( )   PDF in ScienceDirect  
    The flight capacity of different ages and sexes of the sycamore lace bug, Corythucha ciliata, was studied at different temperatures using a flight mill system.  The results of regression analysis showed a significant effect of temperature on flight distance (P=0.0082).  Temperature did not influence flight duration (P=0.212) or flight speed (P=0.175).  The mean flight distance (1 024 m) and mean flight duration were the greatest at 25.2°C.  The age of C. ciliata had a significant influence on flight distance (P=0.0005), flight duration (P=0.0005) and flight speed (P=0.026).  The 12-d-old adult had the greatest flight distance (887 m), duration (3 875 s) and speed (0.22 m s–1).  Flight distances and flight duration of females were significantly longer than that of males.  However, the male had significantly greater flight speed than the female.  The insect appears to be capable of long distance flights.  The understanding of the optimal age and temperature for the flight of this insect through this study provides a foundation for better management of the insect in China.
    Animal Science · Veterinary Medicine
    Mitochondrial DNA diversity and origin of indigenous pigs in South China and their contribution to western modern pig breeds
    WANG Chen, CHEN Yao-sheng, HAN Jian-lin, MO De-lin, LI Xiu-jin, LIU Xiao-hong
    2019, 18(10): 2338-2350.  DOI: 10.1016/S2095-3119(19)62731-0
    Abstract ( )   PDF in ScienceDirect  
    Indigenous pigs in South China are valuable genetic resources with many specific and unique characters, which have played an important role in the establishment of some western modern pig breeds.  However, the origin and genetic diversity of indigenous pigs in South China have not been fully understood.  In the present study, we sequenced 534 novel mitochondrial DNA (mtDNA) D-loop and assembled 54 complete mitogenome sequences for all 17 indigenous pig breeds from Fujian, Guangdong, Guangxi and Hainan in South China.  These data were analyzed together with previously published homologous sequences relevant to this study.  We found that all 13 coding genes of the mitogenomes were under purifying selection, but ND1 had the most variable sites and CYTB contained the most non-synonymous SNPs.  Phylogenetic analysis showed that all indigenous pigs in South China were clustered into the D haplogroup with D1a1, D1b, D1c and D1e sub-haplogroups found to be dominant.  Haplotype and nucleotide diversities of D-loop sequences ranged from 0.427 to 0.899 and from 0.00342 to 0.00695, respectively, among which all pigs in Guangdong had the lowest diversity.  The estimates of pairwise FST, gene flow (Nm) and genetic distance (Da) indicated that most of these indigenous pig breeds differentiated from each other significantly (P<0.05).  Among the western modern breeds, Berkshire and Yorkshire had significant Asian matrilineal footprints from indigenous pigs in South China, especially the Spotted pigs distributed in Guangdong and Guangxi.  The neutrality test (Fu’s FS) indicated that indigenous pigs from Fujian and Guangxi had gone through recent population expansion events (P<0.05).  It is concluded that indigenous pigs in South China were most likely derived from the Mekong region and the middle and downstream regions of Yangtze River through Guangxi and Fujian.  Our findings provide a complete and in-depth insight on the origin and distribution pattern of maternal genetic diversity of indigenous pigs in South China.
    Identification of SNPs and expression patterns of FZD3 gene and its effect on wool traits in Chinese Merino sheep (Xinjiang Type)
    ZHAO Bing-ru, FU Xue-feng, TIAN Ke-chuan, HUANG Xi-xia, DI Jiang, BAI Yan, XU Xin-ming, TIAN Yue-zhen, WU Wei-wei, ABLAT Sulayman, ZENG Wei-dan, HANIKEZI Tulafu
    2019, 18(10): 2351-2360.  DOI: 10.1016/S2095-3119(19)62735-8
    Abstract ( )   PDF in ScienceDirect  
    As a member of the Frizzled family, Frizzled3 (FZD3) is a receptor of the canonical Wnt signaling pathway and plays a vital role in mammalian hair follicle developmental processes.  However, its effects on wool traits are not clear.  The objectives of this study were to identify the single nucleotide polymorphisms (SNPs) and the expression patterns of FZD3 gene, and then to determine whether it affected wool traits of Chinese Merino sheep (Xinjiang Type) or not.  PCR-single stranded conformational polymorphism (PCR-SSCP) and sequencing were used to identify mutation loci, and general linear model (GLM) with SAS 9.1 was used for the association analysis between wool traits and SNPs.  Quantitative real-time PCR (qRT-PCR) was used to investigate FZD3 gene expression levels.  The results showed that six exons of FZD3 gene were amplified and two mutation loci were identified in exon 1 (NC_019459.2: g.101771685 T>C (SNP1)) and exon 3 (NC_019459.2: g.101810848, A>C (SNP2)), respectively.  Association analysis showed that SNP1 was significantly associated with mean fiber diameter (MFD) (P=0.04) and live weight (LW) (P=0.0004), SNP2 was significantly associated with greasy fleece weight (GFW) (P=0.04).  The expression level of FZD3 gene in skin tissues of the superfine wool (SF) group was significantly lower (P<0.05) than that of the fine wool (F) group.  Moreover, it had a higher expression level (P<0.01) in skin tissues than in other tissues of Chinese Merino ewes.  While, its expression level had a fluctuant expression in skin tissues at different developmental stages of embryos and born lambs, with the highest expression levels (P<0.01) at the 65th day of embryos.  Our study revealed the genetic relationship between FZD3 variants and wool traits and two identified SNPs might serve as potential and valuable genetic markers for sheep breeding and lay a molecular genetic foundation for sheep marker-assisted selection (MAS).
    Generation of recombinant rabies virus ERA strain applied to virus tracking in cell infection
    ZHAO Dan-dan, SHUAI Lei, GE Jin-ying, WANG Jin-liang, WEN Zhi-yuan, LIU Ren-qiang, WANG Chong, WANG Xi-jun, BU Zhi-gao
    2019, 18(10): 2361-2368.  DOI: 10.1016/S2095-3119(19)62717-6
    Abstract ( )   PDF in ScienceDirect  
    The mechanism of rabies virus (RABV) infection still needs to be further characterized.  RABV particle with self-fluorescent is a powerful viral model to visualize the viral infection process in cells.  Herein, based on a reverse genetic system of the Evelyn-Rokitnicki-Abelseth (rERA) strain, we generated a recombinant RABV rERA-N/mCherry strain that stably expresses an additional ERA nucleoprotein that fuses with the red fluorescent protein mCherry (N/mCherry).  The rERA-N/mCherry strain retained growth property similar to the parent strain rERA in vitro.  The N/mCherry expression showed genetic stability during passage into mouse neuroblastoma (NA) cells and did not change the virulence of the vector.  The rERA-N/mCherry strain was then utilized as a visual viral model to study the RABV-cell binding and internalization.  We directly observed the red self-fluorescence of rERA-N/mCherry particles binding to the cell surface, and further co-localizing with clathrin in the early stage of infection in NA cells by fluorescence microscopy.  Our results showed that the rERA-N/mCherry strain uses clathrin-dependent endocytosis to enter cells, which is consistent with the well-known mechanism of RABV invasion.  The recombinant RABV rERA-N/mCherry thus appears to have the potential to be an effective viral model to further explore the fundamental molecular mechanism of rabies neuropathogenesis.
    Agro-ecosystem & Environment
    Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain, Northwest China
    QIANG Sheng-cai, ZHANG Fu-cang, Miles Dyck, ZHANG Yan, XIANG You-zhen, FAN Jun-liang
    2019, 18(10): 2369-2380.  DOI: 10.1016/S2095-3119(19)62688-2
    Abstract ( )   PDF in ScienceDirect  
    Excessive use of nitrogen (N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution.  Therefore, determination of optimum N requirements for plant growth is necessary.  Previous studies mostly established critical N dilution curves based on aboveground dry matter (DM) or leaf dry matter (LDM) and stem dry matter (SDM), to diagnose the N nutrition status of the whole plant.  As these methods are time consuming, we investigated the more rapidly determined leaf area index (LAI) method to establish the critical nitrogen (Nc) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China.  Field experiments were conducted using four N fertilization levels (0, 105, 210 and 315 kg ha−1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons.  LAI, DM, plant N concentration (PNC) and grain yield were determined.  Data points from four cultivars were used for establishing the Nc curve and data points from the remaining two cultivars were used for validating the curve.  The Nc dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values.  The N nutrition index (NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit (Nand) ranged from 60.38 to –17.92 kg ha−1 during the growing season.  The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function.  The Nc curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.
    Substitution of chemical fertilizer by Chinese milk vetch improves the sustainability of yield and accumulation of soil organic carbon in a double-rice cropping system
    ZHOU Xing, LU Yan-hong, LIAO Yu-lin, ZHU Qi-dong, CHENG Hui-dan, NIE Xin, CAO Wei-dong, NIE Jun
    2019, 18(10): 2381-1392.  DOI: 10.1016/S2095-3119(18)62096-9
    Abstract ( )   PDF in ScienceDirect  
    The double-rice cropping system is a very important intensive cropping system for food security in China.  There have been few studies of the sustainability of yield and accumulation of soil organic carbon (SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch (Mv).  We conducted a 10-year (2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application (22.5 Mg ha–1).  Fertilizer and Mv were applied both individually and in combination (sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively).  It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve.  The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100.  However, the grain yields increased in the MF80 (by 8.4% compared to the F100), while the SOC stock only increased by 8.4%.  Analogous to the change of grain yield, the sustainable yield index (SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40.  After a certain amount of Mv input (22.5 Mg ha–1), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass.  Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate (with the value higher by 71.6 and 70.1%), whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0.  Based on the above results we suggested that Mv could partially replace chemical fertilizers (e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China.
    Fusing multi-source data to map spatio-temporal dynamics of winter rape on the Jianghan Plain and Dongting Lake Plain, China
    TAO Jian-bin, LIU Wen-bin, TAN Wen-xia, KONG Xiang-bing, XU Meng
    2019, 18(10): 2393-2407.  DOI: 10.1016/S2095-3119(19)62577-3
    Abstract ( )   PDF in ScienceDirect  
    Mapping crop distribution with remote sensing data is of great importance for agricultural production, food security and agricultural sustainability.  Winter rape is an important oil crop, which plays an important role in the cooking oil market of China.  The Jianghan Plain and Dongting Lake Plain (JPDLP) are major agricultural production areas in China.  Essential changes in winter rape distribution have taken place in this area during the 21st century.  However, the pattern of these changes remains unknown.  In this study, the spatial and temporal dynamics of winter rape from 2000 to 2017 on the JPDLP were analyzed.  An artificial neural network (ANN)-based classification method was proposed to map fractional winter rape distribution by fusing moderate resolution imaging spectrometer (MODIS) data and high-resolution imagery.  The results are as follows: (1) The total winter rape acreages on the JPDLP dropped significantly, especially on the Jianghan Plain with a decline of about 45% during 2000 and 2017.  (2) The winter rape abundance keeps changing with about 20–30% croplands changing their abundance drastically in every two consecutive observation years.  (3) The winter rape has obvious regional differentiation for the trend of its change at the county level, and the decreasing trend was observed more strongly in the traditionally dominant agricultural counties.
    Agricultural Economics and Management
    Technical efficiency of hybrid maize growers: A stochastic frontier model approach
    Imad Ali, HUO Xue-xi, Imran Khan, Hashmat Ali, Khan Baz, Sufyan Ullah Khan
    2019, 18(10): 2408-2421.  DOI: 10.1016/S2095-3119(19)62743-7
    Abstract ( )   PDF in ScienceDirect  
    This study investigated the effect of credit constraints and credit unconstraints on the technical efficiency of hybrid maize growers in the Khyber Pakhtunkhwa Province (KPK) of Pakistan. The primary data were collected by a direct elicitation method from 510 maize growers of KPK Province. Stochastic frontier model techniques were used for technical efficiency analyses. The results revealed that the mean technical efficiency difference between the two groups was 10.2%. The results of technical inefficiency effect modeling demonstrated that education of the household head, family size, number of married family members, off-farm income, farming experience, tractor drill, water irrigation through a lined course, certified seed, extension services, household saving variables, and a credit size variable had positive effects on technical efficiency for both credit constrained farmers (CCFs) and credit unconstrained farmers (UCCFs). In addition, age of household head and fragmented land values had negative effects on technical efficiency for both groups. However, the interest rate had positive and negative impacts on the technical efficiency of CCFs and UCCFs, respectively. Our results have significant implications for policies related to land use, interest rate, and banking sector expansion in the rural areas of Pakistan.
    More children nutrition distribution, less labor incentive: Evidence from Chinese collective agriculture
    HUANG Ying-wei, MAO Pei, LI Jun
    2019, 18(10): 2422-2433.  DOI: 10.1016/S2095-3119(19)62733-4
    Abstract ( )   PDF in ScienceDirect  
    Distribution system will affect the labor incentive that has been heatedly discussed by recent literatures. Using a unique micro dataset, this paper demonstrates that the equalitarian distribution system is one of the reasons for the insufficient labor incentive during the Chinese Collective Agriculture period. Specifically speaking, in the distribution of basic rations, the proportion for children (aged 1–3 and 4–7 years) was often beyond their nutrition demand, resulting the dissatisfaction of other families with more laborers and less children, thus these households will reduce their labor supply gradually. At the same time, the existence of outstanding accounts makes it a failure to use work points to buy distributions, which is the mechanism of the distribution system and insufficient labor incentive. All the results have been accepted by the robustness tests. The study will help to understand the distribution system and labor incentive, as well as the failure of the Chinese collective agriculture.