2019 Vol. 18 No. 5 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
    Food Science
    Short Communication

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    Crop Science
    Characterization of TaCOMT genes associated with stem lignin content in common wheat and development of a gene-specific marker
    FU Lu-ping, XIAO Yong-gui, YAN Jun, LIU Jin-dong, WEN Wei-e, ZHANG Yong, XIA Xian-chun, HE Zhong-hu
    2019, 18(5): 939-947.  DOI: 10.1016/S2095-3119(18)61958-6
    Abstract ( )   PDF in ScienceDirect  
    Stem lignin content (SLC) in common wheat (Triticum aestivum L.) contributes to lodging resistance.  Caffeic acid 3-O-methyltransferase (COMT) is a key enzyme involved in lignin biosynthesis.  Characterization of TaCOMT genes and development of gene-specific markers could enable marker-assisted selection in wheat breeding.  In the present study, the full-length genomic DNA (gDNA) sequences of TaCOMT genes located on chromosomes 3A, 3B, and 3D were cloned by homologous cloning.  Two allelic variants, TaCOMT-3Ba and TaCOMT-3Bb, were identified and differed by a 222-bp insertion/deletion (InDel) in the 3´-untranslated region (3´-UTR).  A co-dominant gene-specific marker based on this InDel was developed and designated as TaCOMT-3BM.  A total of 157 wheat cultivars and advanced lines grown in four environments were used to validate the associations between allelic patterns and SLC.  The SLC of cultivars with TaCOMT-3Ba was significantly (P<0.01) higher than that of those with TaCOMT-3Bb, and the marker TaCOMT-3BM could be effectively used in wheat breeding.
    Phenotypic characterization and genetic mapping of the dwarf mutant m34 in maize
    LI Jie-ping, Soomro Ayaz Ali, XIAO Gui, CHEN Fan-jun, YUAN Li-xing, GU Ri-liang
    2019, 18(5): 948-957.  DOI: 10.1016/S2095-3119(18)61959-8
    Abstract ( )   PDF in ScienceDirect  
    Plant height is one of the most important agronomic traits associated with yield in maize.  In this study, a gibberellins (GA)-insensitive dwarf mutant, m34, was screened from inbred line Ye478 by treatment with the chemical mutagen ethyl-methanesulfonate (EMS).  Compared to Ye478, m34 showed a dwarf phenotype with shorter internodes, and smaller leaf length and width, but with similar leaf number.  Furthermore, m34 exhibited smaller guard cells in internodes than Ye478, suggesting that smaller cells might contribute to its dwarf phenotype.  Genetic analysis indicated that the m34 dwarf phenotype was controlled by a recessive nuclear gene.  An F2 population derived from a cross between m34 and B73 was used for mutational gene cloning and this gene was mapped to a chromosome region between umc2189 and umc1553 in chromosome 1 bin1.10, which harbored a previously identified dwarf gene ZmVP8.  Sequencing analysis showed a nucleotide substitution (G1606 to A1606) in the sixth exon of ZmVP8, which resulted in an amino acid change (E531 to K531) from Ye478 to m34.  This amino acid change resulted in an α-helix changing to a β-sheet in the secondary protein structure and the ‘SPEC’ domain changed to a ‘BOT1NT’ domain in the tertiary protein structure.  Taken together, these results suggested that m34 is a novel allelic mutant originally derived from Ye478 that is useful for further ZmVP8 functional analysis in maize.
    Morphological diversity and correlation analysis of phenotypes and quality traits of proso millet (Panicum miliaceum L.) core collections
    ZHANG Da-zhong, Rabia Begum Panhwar, LIU Jia-jia, GONG Xiang-wei, LIANG Ji-bao, LIU Minxuan, LU Ping, GAO Xiao-li, FENG Bai-li
    2019, 18(5): 958-969.  DOI: 10.1016/S2095-3119(18)61997-5
    Abstract ( )   PDF in ScienceDirect  
    Genetic diversity and comprehensive performance are the basis for the discovery and efficient use of proso millet (Panicum miliaceum L.) core collections.  In this study, 386 proso millet core collections were used as materials to observe inflorescence color, leaf phase, inflorescence density, axis shape, branched spike length, panicle type, trichome, measured area of the top3 leaves, and chlorophyll content of the top3 leaves at filling stage.  These core collections were also used to record growth period, plant height, diameter of main stem, plant tiller number, branch number, panicle length, panicle number per plant, and panicle weight per plant at the maturation stage.  Starch, fat, protein, and yellow pigment contents in the grain and 1 000-seed weight were also measured after harvest.  Then, quantitative traits were used for diversity analysis and comprehensive evaluation of each collection.  Correlations between all traits were also analyzed.  Results showed that among the 8 quality traits, the Shannon index (H´) of hull color was the highest (1.588) followed by the H´ of inflorescence density (0.984).  However, inflorescence color and axis shape were lower.  The H´ of 16 quantitative traits were significantly higher than the quality traits with the following traits having the highest indices: fat content (2.092), 1 000-seed weight (2.073), top3 leaves area (2.070), main stem diameter (2.056), and plant height (2.052).  Furthermore, all other traits had a diversity higher than 1.900.  After a comprehensive evaluation of phenotypic traits, plant height, diameter of main stem, plant tiller number, leaf area of top3 leaves, and 1 000-seed weight were the biggest contributors to the principal components.  Six high-fat and high-protein cultivars, including Nuoshu, A75-2, Zhiduoaosizhi, Panlonghuangmi, Xiaobaishu, and Xiaohongshu were also screened.  Correlations between the quantitative traits were significant, including the correlation between quality traits and quantitative traits.  In conclusion, the core collections can be used as basis for discriminating among proso millet cultivars based on related traits and for further studies on millet with rich genetic diversity, good representation, and significant collection between traits.
    Field identification of morphological and physiological traits in two special mutants with strong tolerance and high sensitivity to drought stress in upland rice (Oryza sativa L.)
    HUANG Min, XU Yu-hui, WANG Hua-qi
    2019, 18(5): 970-981.  DOI: 10.1016/S2095-3119(18)61909-4
    Abstract ( )   PDF in ScienceDirect  
    The two mutants idr1-1 and 297-28, which were obtained from the radiation mutation of HD297 and IAPAR9, were used as experimental materials in this study for a 2-year (2012 and 2013) experiment about field drought resistance identification in Beijing, China.  Key agronomic traits and water-related physiological indexes were observed and measured, including the leaf anti-dead level (LADL), days to heading, plant height, setting percentage, aboveground biomass, leaf water potential (LWP), net photosynthetic rate (Pn) and transpiration rate.  The results showed that the mutant idr1-1 that was under drought stress (DS) conditions for 2 years had the highest LADL grades (1.3 and 2.0) among all the materials, and they were 2–3 grades stronger than the wild-type IAPAR9 with an average that was 21.4% higher for the setting percentage than the wild type.  Compared with the IAPAR9 for the 2-year average delay in the days to heading and the reduction rates in the plant height, setting percentage, and aboveground biomass under DS compared with the well-watered (WW) treatment, idr1-1 showed 3.2% less delay and 19.1, 16.4, and 6.1% less reduction, respectively.  The idr1-1 in the LWP always exhibited the highest performance among all the materials.  The Pn of idr1-1 under severe and mild DS comparing with that under WW was slightly decreased and even slightly increased, respectively, leading to an average reduction rate of only 0.92%, which was 26.93% less than that of IAPAR9.  Under the severe DS, idr1-1 still showed the highest value of 16.88 μmol CO2 m–2 s–1 among all the materials and was significantly higher than that of IAPAR9 (11.66 μmol CO2 m–2 s–1).  Furthermore, only idr1-1 had the increased and the highest transpiration rate values (7.6 and 6.04 mmol H2O m–2 s–1) under both mild and severe DS compared with the values under WW, when the transpiration rate of all the other materials significantly decreased.  By contrast, the 297-28 in terms of the LADL grade under DS was the lowest (7.0), and it was four grades weaker than its wild-type HD297 and even one grade weaker than the drought-sensitive paddy rice SN265.  For the 2-year average reduction rates in aboveground biomass and plant heights under DS compared with those under the WW, 297-28 was 31.6 and 31.8% higher than HD297, respectively.  Meanwhile, 297-28 showed the worst performance for the LWP, Pn, and transpiration rate.  These results suggest that idr1-1 might be a superior drought tolerant mutant of upland rice found in China.  It has a strong ability to maintain and even enhance leaf transpiration while maintaining a high plant water potential under DS, thus supporting a high Pn and alleviating the delay in agronomic trait development and yield loss effectively.  297-28 is a much more highly drought-sensitive mutant that is even more sensitive than paddy rice varieties.  The two mutants could be used as drought tolerance controls for rice germplasm identification and the drought resistant mechanism studies in the future.  idr1-1 is also suitable for breeding drought-tolerant and lodging-resistant high-yield rice varieties.
    Mulching with plastic film improved the root quality of summer-sown sweet potato (Ipomoea batatas (L). Lam.) in northern China
    HOU Fu-yun, DONG Shun-xu, XIE Bei-tao, ZHANG Hai-yan, LI Ai-xian, WANG Qing-mei
    2019, 18(5): 982-991.  DOI: 10.1016/S2095-3119(18)61994-X
    Abstract ( )   PDF in ScienceDirect  
    The root quality of sweet potato cultivated during the summer season is poor in northern China; thus, this study was conducted to determine whether root quality could be improved through mulching with plastic film (MPF).  The effect of MPF on root starch and its composition, the activity of starch synthesis enzymes, and other quality-related parameters were investigated in two purple flesh sweet potato cultivars, Jishu 18 and Ayamurasaki (Aya).  The results indicated that root dry matter, anthocyanin content, adenosine triphosphate (ATP), and starch content were higher in both cultivars under the MPF treatment than those under the control treatment.  The root adenosine diphosphate glucose pyrophosphorylase/uridine diphosphate glucose pyrophosphorylase (ADPGPPase/UDPGPPase) activity and adenosine triphosphatease (ATPase) activity were increased using MPF.  However, under the MPF treatment, the amylose content, soluble sugar content, and granule-bound synthase (GBSS) activity increased in Jishu 18 but decreased in Aya, and the amylopectin content, protein content, and soluble starch synthase (SSS) activity decreased in Jishu 18 but increased in Aya.  Therefore, MPF seems benifit to improve the quality of sweet potato, but the effects of this treatment condition may be dependent on the cultivar.
    Crosstalk of cold and gibberellin effects on bolting and flowering in flowering Chinese cabbage
    SONG Shi-wei, LEI Yu-ling, HUANG Xin-min, SU Wei, CHEN Ri-yuan, HAO Yan-wei
    2019, 18(5): 992-1000.  DOI: 10.1016/S2095-3119(18)62063-5
    Abstract ( )   PDF in ScienceDirect  
    The flower stalk is the product organ of flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee), which is cultivated extensively in South China.  Flower stalk formation and development, including bolting and flowering, determine the yield of flowering Chinese cabbage; however, the bolting and flowering mechanisms remain to be explored.  To elucidate these processes, we studied the effects of low-temperature and gibberellin (GA) treatments, and their interaction, on stem elongation, bolting time, flowering time, hormone content, and cell morphology in stem of flowering Chinese cabbage.  The results showed that both cold and GA treatments accelerated bolting time, stem elongation, and flowering time.  Moreover, cold and GA cotreated plants displayed additive positive effects.  In addition, cold treatments increased the GA, indole-3-acetic acid, and cytokinin contents and altered cell size in the shoot apices of flowering Chinese cabbage.  Treatment with uniconazole, a GA synthesis inhibitor, strongly delayed bolting time, stem elongation, and flowering time, whereas GA, but not cold treatment, rescued this inhibition, indicating that low temperature accelerates bolting and flowering not only through inducing GA in the shoot apices, but also other ways.  These results provide a theoretical basis for further dissecting the regulatory mechanism of bolting and flowering in flowering Chinese cabbage.
    Foliar spraying of aqueous garlic bulb extract stimulates growth and antioxidant enzyme activity in eggplant (Solanum melongena L.)
    Muhammad Ali, CHENG Zhi-hui, Sikandar Hayat, Husain Ahmad, Muhammad Imran Ghani, LIU Tao
    2019, 18(5): 1001-1013.  DOI: 10.1016/S2095-3119(18)62129-X
    Abstract ( )   PDF in ScienceDirect  
    Recently, botanical extracts are gaining popularity as biostimulants in vegetable production.  In present study, the effect of aqueous garlic bulb extract (AGE) was studied on the growth and physiology of eggplant grown in plastic tunnel.  AGE was foliage sprayed with various frequencies, i.e., 0, S1 (once), S2 (twice) and S3 (three times) at two independent growth stages, pre- and post-transplant.  The results showed that the treated plants exhibited stimulatory responses in growth and physiology in accord with the repetition of AGE spray and growth stages of the plants, respectively.  A single foliage sprayed pre-transplant resulted in improved growth, i.e., plant morphology and biomass, and enhanced antioxidants enzymes (superoxide dismutase, SOD; peroxidase, POD), photosynthesis and chlorophyll abundance observed at vegetative, first flowering and fruit setting stages, respectively.  However, thrice application inhibited the plant growth and development and resulted in lipid peroxidation, i.e., increased malondialdehyde (MDA) content.  In addition, the post-transplant application also showed growth stimulation and interestingly, an overall positive influence was observed with respect to the AGE application and no significant increase in the MDA content indicated the post-transplant seedlings responded well.  Our findings demonstrate that AGE can act as a biostimulant to enhance the eggplant growth in plastic tunnel production.
    Plant Protection
    Seedling and adult plant resistance to leaf rust in 46 Chinese bread wheat landraces and 39 wheat lines with known Lr genes
    ZHANG Pei-pei, Takele Weldu Gebrewahid, ZHOU Yue, LI Qing-luo, LI Zai-feng, LIU Da-qun
    2019, 18(5): 1014-1023.  DOI: 10.1016/S2095-3119(19)62575-X
    Abstract ( )   PDF in ScienceDirect  
    Wheat leaf rust, caused by Puccinia triticina (Pt), is an important foliar disease that has an important influence on wheat yield.  The most economic, safe and effective way to control the disease is growing resistant cultivars.  In the present study, a total of 46 wheat landraces and 34 wheat lines with known Lr (leaf rust resistance) genes were inoculated with 16 Pt pathotypes for postulating seedling resistance gene(s) in the greenhouse.  These cultivars and five wheat differential lines with adult plant resistance (APR) genes (Lr12, Lr22b, Lr34, Lr35 and Lr37) were also evaluated for identification of slow rusting resistance in the field trials in Baoding, Hebei Province of China in the 2014–2015 and 2015–2016 cropping seasons.  Furthermore, 10 functional molecular markers closely linked to 10 known Lr genes were used to detect all the wheat genotypes.  Results showed that most of the landraces were susceptible to most of the Pt pathotypes at seedling stage.  Nonetheless, Lr1 was detected only in Hongtangliangmai.  The field experimental test of the two environments showed that 38 landraces showed slow rusting resistance.  Seven cultivars possessed Lr34 but none of the landraces contained Lr37 and Lr46Lr genes namely, Lr9, Lr19, Lr24, Lr28, Lr29, Lr47, Lr51 and Lr53 were effective at the whole plant stage.  Lr18, Lr36 and Lr45 had lost resistance to part of pathotypes at the seedling stage but showed high resistance at the adult plant stage. Lr34 as a slowing rusting gene showed good resistance in the field.  Four race-specific APR genes Lr12, Lr13, Lr35 and Lr37 conferred good resistance in the field experiments.  Seven race-specific genes, Lr2b, Lr2c, Lr11, Lr16, Lr26, Lr33 and LrB had lost resistance.  The 38 landraces showed slow rusting resistance to wheat leaf rust can be used as resistance resources for wheat resistance breeding in China.
    The autophagy gene ATG8 affects morphogenesis and oxidative stress tolerance in Sporisorium scitamineum
    ZHANG Bin, CUI Guo-bing, CHANG Chang-qing, WANG Yi-xu, ZHANG Hao-yang, CHEN Bao-shan, DENG Yi-zhen, JIANG Zi-de
    2019, 18(5): 1024-1034.  DOI: 10.1016/S2095-3119(18)62109-4
    Abstract ( )   PDF in ScienceDirect  
    The basidiomycetous fungus Sporisorium scitamineum causes sugarcane smut that leads to severe economic losses in the major sugarcane growing areas in China, India and Brazil, etc.  Autophagy is a conserved pathway in eukaryotes for bulk degradation and cellular recycling, and was shown to be important for fungal cell growth, development, and pathogenicity.  However, physiological function of autophagy has not been studied in S. scitamineum.  In this study, we identified a conserved Atg8 protein, named as SsAtg8 and characterized its function. Our results showed that autophagy was blocked in the ssatg8Δ mutant, in nitrogen starvation.  The ssatg8Δ mutant formed pseudohypha frequently and was hypersensitive to oxidative stress.  However, mating or filamenation was unaffected in the ssatg8Δ mutant in vitro.  Overall we demonstrate that autophagy is dispensable for S. scitamineum mating/filamentation, while critical for oxidative stress tolerance and proper morphology in sporidial stage.   
    Preparation and characterization of atrazine-loaded biodegradable PLGA nanospheres
    CHEN Xiao-ting, Tongxin Wang
    2019, 18(5): 1035-1041.  DOI: 10.1016/S2095-3119(19)62613-4
    Abstract ( )   PDF in ScienceDirect  
    Atrazine is the second mostly used herbicide in USA, but low utilization ratio causes severe environmental problem, so controlled release system is highly needed in order to minimize the negative impact on environment.  In this paper, a herbicide delivery system, atrazine-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) were prepared by forming an oil-in-water emulsion using the emulsion-solvent evaporation method.  By varying the preparation conditions of PLGA-NPs, such as sonication time, surfactant content, solvent fraction, and polymer content, the particle sizes of the PLGA-NPs were well controlled from 204 to 520 nm.  The morphology and size distribution of PLGA-NPs were evaluated using dynamic light scattering (DLS) and scanning electron microscopy (SEM).  Both the encapsulation efficiency and release profile of the herbicide from the PLGA-NPs were typically evaluated by using 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine, ATZ) as the model.  ATZ encapsulation efficiency within the PLGA-NPs was ranged from 31.6 to 50.5%.  The release profiles of ATZ-loaded PLGA-NPs exhibited a much slower release rate in comparison with that of pure herbicide.  The results demonstrated that the prepared PLGA-NPs had a high encapsulation efficiency and slow release rate, which could be used as a promising herbicide release system in agriculture to diminish the impact on the environment and minimize the potential harm to the farmers. 
    Species-specific COI primers for rapid identification of a globally significant invasive pest, the cassava mealybug Phenacoccus manihoti Matile-Ferrero
    WANG Yu-sheng, TIAN Hu, WAN Fang-hao, ZHANG Gui-fen
    2019, 18(5): 1042-1049.  DOI: 10.1016/S2095-3119(18)62043-X
    Abstract ( )   PDF in ScienceDirect  
    The globally invasive cassava mealybug Phenacoccus manihoti Matile-Ferrero is a pernicious pest of cassava, and its recent introduction into Asia has raised considerable alarm.  To slow or prevent further invasion, an accurate, simple, and developmental-stage-independent detection method for P. manihoti is required.  In the present study, a PCR method based on a species-specific mitochondrial DNA cytochrome oxidase I (SS-COI) marker was developed for rapid identification of P. manihoti.  One pair of SS-COI primers (PMSSZW-1F and PMSSZW-1R) was designed based on sequence variations in the COI gene among P. manihoti and related mealybug species.  Specificity of the primer pair was validated on 21 closely related species.  Sensitivity tests were performed on four immature developmental stages and female adults.  Efficacy tests demonstrated that at the relatively low concentration of (135.2±14.7) pg μL–1 resuspended DNA, the specific fragment was detected in all replicates.  Furthermore, the SS-COI primer pair was assayed on three populations of P. manihoti from major exporting countries of cassava.  The PCR assay was proved to be a rapid, simple, and reliable molecular measure for the identification of P. manihoti.  This tool will be useful for quarantine, monitoring, and management of this invasive pest.
    No evidence for an effect of Wolbachia on mtDNA variation and evolution in natural populations of Sesamia inferens (Lepidoptera: Noctuidae)
    TANG Xiao-tian, XU Jing, LU Ming-xing, DU Yu-zhou
    2019, 18(5): 1050-1063.  DOI: 10.1016/S2095–3119(18)62019–2
    Abstract ( )   PDF in ScienceDirect  
    Wolbachia are widespread maternally-inherited endosymbiotic bacteria that infect numerous arthropods.  This study represents a thorough survey of the Wolbachia infection patterns in the pink stem borer, Sesamia inferens (Walker), an important rice pest in China, based on nucleotide comparisons for the surface protein (wsp) and cell division protein (ftsZ) genes.  The effects of Wolbachia on mtDNA variation and evolution of S. inferens were also investigated.  Although we identified six genetically diverse strains, we found infections to be infrequent, with only 7.8% of hosts infected, and identified geographical differences in infection rates between southern and northern populations.  Nucleotide indexes (haplotype diversity (Hd), nucleotide diversity (π) and number of variable sites (S) of mtDNA in infected populations were not significantly lower or higher than that in the uninfected populations.  Furthermore, there was no association between Wolbachia infection status and phylogeny of mtDNA haplotypes.  Analysis of molecular variance (AMOVA) showed that significant differentiation mainly existed within groups rather than among the groups.  Additionally, using Tajima’s D and Fu’s F values, the mtDNA genes did not deviate significantly from neutral evolution.  Taken together these results indicate that currently there were no effects of Wolbachia infection on host mtDNA variation and evolution in S. inferens.
    Alanine-substituted mutant on Gly373 and Asn375 of Cry1Ai-h-loop 2 causes reduction in both toxicity and binding against Helicoverpa armigera
    LIU Yu-xiao, ZHOU Zi-shan, LIANG Ge-mei, SONG Fu-ping, ZHANG Jie
    2019, 18(5): 1064-1071.  DOI: 10.1016/S2095-3119(18)61933-1
    Abstract ( )   PDF in ScienceDirect  
    Cry1Ai-h-loop 2 is a mutant of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera.  The toxicity of Cry1Ai-h-loop 2, in contrast to the very low toxicity of Cry1Ai, is closely associated with the eleven residues in the loop 2 region.  To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, alanine-substituted mutants were generated.  The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity.  ELISA binding and competition binding assays demonstrated that the reduction of toxicity in the mutant of interest was correlated with decreased binding affinity.
    Animal Science · Veterinary Medicine
    Production of homeobox A10 gene transgenic pigs by somatic cell nuclear transfer
    XIAO Qian, ZHAO Chang-zhi, LIN Rui-yi, LI Guang-lei, LI Chang-chu, WANG Hai-yan, XU Jing, XIE Sheng-song, YU Mei, ZHAO Shu-hong
    2019, 18(5): 1072-1079.  DOI: 10.1016/S2095-3119(19)62582-7
    Abstract ( )   PDF in ScienceDirect  
    Homeobox A10 (Hoxa10) gene is one of the most important candidate genes associated with the reproductive performance of humans and mice.  Overexpression of Hoxa10 in mouse endometrium can increase litter size.  Moreover, Hoxa10 plays a key role in regulating the embryo implantation of sows.  This study aimed to generate transgenic pigs using Hoxa10 via somatic cell nuclear transfer (SCNT).  We established seven Hoxa10-transgenic cell lines, and two of the cell lines were selected as nuclear donors for the transfer.  A total of 1 270 cloned embryos were generated and transferred to five surrogate mothers (Landrace×Yorkshire).  Eight cloned male piglets were produced including one with cryptorchidism.  Six transgenic piglets grew up healthy and produced 56 offspring.  Finally, we obtained six transgenic male pigs and 26 transgenic positive offspring that can be used to further study the regulatory mechanism of Hoxa10 on the reproductive performance of pigs.
    Weaning methods affect ruminal methanogenic archaea composition and diversity in Holstein calves
    DONG Li-feng, MA Jun-nan, TU Yan, DIAO Qi-yu
    2019, 18(5): 1080-1092.  DOI: 10.1016/S2095-3119(18)62120-3
    Abstract ( )   PDF in ScienceDirect  
    The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.  Thirty-six newborn Holstein bull calves were assigned to 1 of 3 treatments: (1) conventional weaning (d 56) and fed a high proportion of solid feed (CWS); (2) conventional weaning (d 56) and fed a high proportion of liquid feed (CWL); (3) early weaning (d 42) and fed with a high proportion of solid feed (EWS).  High-throughput sequencing of the methyl coenzyme M reductase (mcrA) gene, which encodes the α-subunit of methyl coenzyme M reductase - the enzyme that catalyzes the final step in methanogenesis was used to determine the composition and diversity of rumen methanogens.  No significant difference (P>0.05) was observed for operational taxonomic units (OTUs) or richness indices, but diversity indices increased (P<0.05) for calves fed high dietary solids.  Predominant families across the three treatments were Methanobacteriaceae, Thermoplasmataceae and Methanomassiliicoccaceae.  Calves in the EWS treatment had a higher (P<0.05) relative abundance of Methanobrevibacter sp. strain AbM4 and Methanosphaera stadtmanae, while calves in the CWL treatment had a higher (P<0.05) abundance of Methanosphaera sp. strain SM9.  A positive (P<0.05) relationship was identified between butyrate and Methanobrevibacter sp. strain AbM4.  In conclusion, the composition and diversity of methanogens in the rumen of Holstein calves varied under the different weaning methods.  This study identified a positive relationship between butyrate and Methanobrevibacter sp. strain AbM4, potentially reflecting correlations between ruminal fermentation variables and methanogenesis function.  These in-depth analyses provide further understanding of weaning methods for intensified production systems. 
    Evaluating the efficacy of an attenuated Streptococcus equi ssp. zooepidemicus vaccine produced by multi-gene deletion in pathogenicity island SeseCisland_4
    MA Fang, WANG Guang-yu, ZHOU Hong, MA Zhe, LIN Hui-xing, FAN Hong-jie
    2019, 18(5): 1093-1102.  DOI: 10.1016/S2095-3119(18)62133-1
    Abstract ( )   PDF in ScienceDirect  
    Streptococcus equi ssp. zooepidemicus (SEZ) is a pathogen associated with a wild range of animal species.  Frequent outbreaks have occurred in recent years in pigs, horses, goats and dogs which is liable to infect humans.  There is a lack of efficient vaccines against this disease and the occurrence of antibiotic resistance may render drug therapies ineffective.  In this study, gene deletion mutant (ΔSEZ) in pathogenicity islands SeseCisland_4 was constructed.  The mutant ΔSEZ had a 52-fold decrease in 50% lethal dose (LD50) and had less capacity to adhere epithelial cells.  Importantly, immunization of mice with attenuated vaccine ΔSEZ at the dose of 102 colony-forming units (CFU) mL–1 elicited a significant humoral antibody response, with an antibody titer of 1:12 800.  Therefore, 102 CFU mL–1 might be used as the appropriate immune dose for the attenuated vaccine ΔSEZ, which provided mice with efficient protection against virulent SEZ.  In addition, the hyperimmune sera against 102 CFU mL–1 attenuated vaccine ΔSEZ could confer significant protection against virulent SEZ infection in the passive immunization experiment and exhibited efficient bactericidal activity in the whole blood assay.  Meanwhile, no viable bacteria was detected in blood when mice were immunized with ΔSEZ at the dose of 102 CFU mL–1 via hypodermic injection.  Thereafter, the mutant ΔSEZ at the dose of 102 CFU mL–1 could confer significant protection in mice and had less negative effects on host, which could be an effective attenuated vaccine candidate for the prevention of SEZ.
    Agro-ecosystem & Environment
    Carbon cycle in response to residue management and fertilizer application in a cotton field in arid Northwest China
    ZHANG Peng-peng, XU Shou-zhen, ZHANG Guo-juan, PU Xiao-zhen, WANG Jin, ZHANG Wang-feng
    2019, 18(5): 1103-1119.  DOI: 10.1016/S2095-3119(18)62075-1
    Abstract ( )   PDF in ScienceDirect  
    Understanding the influence of farming practices on carbon (C) cycling is important for maintaining soil quality and mitigating climate change, especially in arid regions where soil infertility, water deficiency, and climate change had significantly influenced on agroecosystem.  A field experiment was set up in 2009 to examine the influence of residue management and fertilizer application on the C cycle in a cotton field in the Xinjiang Uygur Autonomous Region of Northwest China.  The study included two residue management practices (residue incorporation (S) and residue removal (NS)) and four fertilizer treatments (no fertilizer (CK), organic manure (OM), chemical fertilizer (NPK), chemical fertilizer plus organic manure (NPK+OM)).  Soil organic carbon (SOC) and some of its labile fractions, soil CO2 flux, and canopy apparent photosynthesis were measured during the cotton growing seasons in 2015 and 2016.  The results showed that SOC, labile SOC fractions, canopy apparent photosynthesis, and soil CO2 emission were significantly greater in S+NPK+OM (residue incorporation+chemical fertilizer) than in the other treatments.  Analysis of all data showed that canopy apparent photosynthesis and soil CO2 emission increased as SOC increased.  The S+OM (residue incorporation+organic manure) and S+NPK+OM treatments were greater for soil C sequestration, whereas the other treatments resulted in soil C loss.  The S+NPK treatment is currently the standard management practice in Xinjiang.  The results of this study indicate that S+NPK cannot offset soil C losses due to organic matter decomposition and autotrophic respiration.  Residue return combined with NPK fertilizer and organic manure application is the preferred strategy in arid regions for increasing soil C sequestration. 
    Interaction effect of nitrogen form and planting density on plant growth and nutrient uptake in maize seedlings
    WANG Peng, WANG Zhang-kui, SUN Xi-chao, MU Xiao-huan, CHEN Huan, CHEN Fan-jun, Yuan Lixing, MI Guo-hua
    2019, 18(5): 1120-1129.  DOI: 10.1016/S2095-3119(18)61977-X
    Abstract ( )   PDF in ScienceDirect  
    High planting density is essential to increasing maize grain yield.  However, single plants suffer from insufficient light under high planting density.  Ammonium (NH4+) assimilation consumes less energy converted from radiation than nitrate (NO3).  It is hypothesized that a mixed NO3/NH4+supply is more important to improving plant growth and population productivity under high vs. low planting density.  Maize plants were grown under hydroponic conditions at two planting densities (low density: 208 plants m–2 and high density: 667 plants m–2) and three nitrogen forms (nitrate only, 75/25NO3/NH4+ and ammonium only).  A significant interaction effect was found between planting density and N form on plant biomass.  Compared to nitrate only, 75/25NO3/NH4+ increased per-plant biomass by 44% under low density, but by 81% under high density.  Treatment with 75/25NO3/NH4+ increased plant ATP, photosynthetic rate, and carbon amount per plant by 31, 7, and 44% under low density, respectively, but by 51, 23, and 95% under high density.  Accordingly, carbon level per plant under 75/25NO3/NH4+ was improved, which increased leaf area, specific leaf weight and total root length, especially for high planting density, increased by 57, 17 and 63%, respectively.  Furthermore, under low density, 75/25NO3/NH4+ increased nitrogen uptake rate, while under high density, 75/25NO3/NH4+ increased nitrogen, phosphorus, copper and iron uptake rates.  By increasing energy use efficiency, an optimum NO3/NH4+ ratio can improve plant growth and nutrient uptake efficiency, especially under high planting density.  In summary, an appropriate supply of NH4+ in addition to nitrate can greatly improve plant growth and promote population productivity of maize under high planting density, and therefore a mixed N form is recommended for high-yielding maize management in the field.
    Polyaspartic acid mediates the absorption and translocation of mineral elements in tomato seedlings under combined copper and cadmium stress
    HU Mei-mei, DOU Qiao-hui, CUI Xiu-min, LOU Yan-hong, ZHUGE Yu-ping
    2019, 18(5): 1130-1137.  DOI: 10.1016/S2095-3119(18)62017-9
    Abstract ( )   PDF in ScienceDirect  
    Polyaspartic acid (PASP) is a nontoxic, biodegradable, environmentally friendly polymer and is widely used as a fertilizer synergist in agricultural production.  In many old orchards and vegetable gardens, highly fertile soil is often accompanied by severe heavy metal contamination.  The present study was designed to investigate mineral element interactions mediated by PASP under copper (Cu)+cadmium (Cd) combined stress to provide reasonable suggestions for scientific fertilization.  A pot experiment was conducted in which tomato seedlings served as plant materials.  A concentration of 700 mg L–1 PASP and foliar spraying application methods were selected based on previous experiments.  Four treatments were applied: normal soil (control (CK)), Cu+Cd (combined stress), Cu+Cd+PASP, and normal soil+PASP.  The plant biomass, root activity, and mineral elements were measured, and these data were analyzed by Data Processing System (DPS) statistical software.  The results showed that, under Cu+Cd combined stress, PASP promoted stem diameter growth, root activity and chlorophyll content and ultimately increased the biomass of tomato seedlings to different degrees.  Moreover, the content of both Cu and Cd and their individual accumulation in plants decreased.  PASP increased the distribution of Cu and Cd in the roots under Cu+Cd combined stress, and the translocation ability from the roots to shoots was significantly restricted.  With respect to essential elements, PASP promoted mainly the absorption and translocation of potassium (K), calcium (Ca), and magnesium (Mg), which greatly exerted physiological roles.  However, the variation trends of Cu and Cd under normal soil conditions contrasted with those under stress conditions.  With respect to essential elements other than K, Ca, and Mg, PASP mostly restrained their absorption but promoted their translocation.  The regulatory mechanism of PASP differed between the combined stress conditions and normal soil conditions.  Under the combined stress conditions, PASP seemed to mainly promote these advantageous factors that exert physiological regulatory functions.  Under normal soil conditions, PASP mainly acted as a biological stimulant or signaling molecule for increased nutrient efficiency, which caused greater biomass productivity. 
    Effect of grazing time and intensity on growth and yield of spring wheat (Triticum aestivum L.)
    Ketema Tilahun Zeleke
    2019, 18(5): 1138-1147.  DOI: 10.1016/S2095-3119(18)62125-2
    Abstract ( )   PDF in ScienceDirect  
    A simulated grazing field experiment was conducted to determine the effect of timing and intensity of grazing on the growth and yield of a mid-late maturing spring wheat (cv. Flanker) under different watering regimes, at Wagga Wagga in south-eastern Australia.  The experiment was a factorial design of watering regime and pasture “grazing” as factors, with three replications.  The two watering regimes were rainfed (R) and supplemental irrigation (I).  There were four simulated grazing treatments: no grazing, “crash” grazing by mowing to 5 cm height on 13 June (Cut1-5), “crash” grazing by mowing to 5 cm on 15 July (Cut2-5) and “clip” grazing by mowing to 15 cm height on 15 July (Cut2-15).  The lowest dry matter (simulated grazing) was obtained from RCut1-5 (0.13 t ha–1) and the highest (0.86 t ha–1) was from ICut2-5.  There was no significant difference (P<0.05) among the grain yields of the grazing treatments in the respective watering regimes.  However, there was significant difference (P<0.05) between the grain yields of the rainfed (3.60 t ha–1) and irrigated (6.0 t ha–1) treatments.  Under both watering regimes, the highest grain yield was obtained from the late “clip” grazings: 3.79 t ha–1 (RCut2-15) for rainfed and 6.47 t ha–1 (ICut2-15) for irrigated treatments.  The lowest grain yield for the rainfed treatment was 3.26 t ha–1 (RCut1-5) and for the irrigated treatments, the lowest grain yield was 5.50 t ha–1 (ICut2-5).   Harvest index (HI) was not significantly affected (P>0.05) by either the watering regime or grazing.  Seed weight was significantly (P<0.05) affected both by the watering regime and grazing with the lowest value for 1 000-seed weight of 30.05 g (RCut2-5) and the highest value of 38.00 g (ICut2-15).  Water use efficiency was significantly (P<0.05) affected both by the watering regime and grazing with the lowest value of 9.94 kg ha–1 mm–1 (ICut2-5) and the highest value 13.43 kg ha–1 mm–1 (RCut2-5).  By “crash” grazing late (just before stem elongation stage) to a height of 5 cm, a significantly higher (P<0.05) above ground dry matter can be grazed without significantly affecting the yield both in seasons with low amount of rainfall and high amount of rainfall (irrigated in this study) although in a wet season a slightly lower (15% lower) grain yield is obtained relative to “clip grazing” to 15 cm height.  Grazing of mid-late maturing wheat cultivars has the potential to fill the feed gap without significantly affecting grain yield.
    Food Science
    Comparison of phenolic profiles and antioxidant activities in skins and pulps of eleven grape cultivars (Vitis vinifera L.)
    LI Fu-xiang, LI Fu-hua, YANG Ya-xuan, YIN Ran, MING Jian
    2019, 18(5): 1148-1158.  DOI: 10.1016/S2095-3119(18)62138-0
    Abstract ( )   PDF in ScienceDirect  
    Eleven grape cultivars were analysed to explore the variety differences of fresh grape phenolic profiles.  The results showed that free phenolics were predominant in grape skins and pulps, and showed the higher antioxidant activities than bound.  In 11 cultivars, Muscat Kyoho extracts had the highest total phenolic content in skins (10.525 mg GAE g–1 FW) and pulps (1.134 mg GAE g–1 FW), and exhibited the highest DPPH radical scavening capacity (EC50=11.7 µg mL–1) and oxygen radical absorbance capacity (ORAC) value (190.57 µmol TE g–1 FW) of free phenolic in skin.  In addition, the most abundant phenolics in grape skins were found to be flavonoids such as kaempferol in Kyoho skin (541.2 µg g–1 FW), rutin, catechin and epicatechin in Muscat Kyoho skin (262.3, 86.3 and 70.0 µg g–1 FW, respectively).  Furthermore, the principal component analysis showed a strong difference of phenolic profiles with the cultivars, existing forms and distributions.  Pearson correlation coefficient analysis showed a significant linear correlation between total phenolic content and antioxidant activity (P<0.05).  Therefore, both skins and pulps were rich sources of bioactive phenolic compounds, and Muscat Kyoho was the ideal source among all samples.
    The chemical treatments combined with antagonistic yeast control anthracnose and maintain the quality of postharvest mango fruit
    SHAO Yuan-zhi, ZENG Jiao-ke, TANG Hong, ZHOU Yi, LI Wen
    2019, 18(5): 1159-1169.  DOI: 10.1016/S2095-3119(18)62128-8
    Abstract ( )   PDF in ScienceDirect  
    During the storage and transportation of the mango fruit, the major source of disease is anthracnose, caused by the fungus Colletotrichum gloeosporioides.  The objective of this study is to find an appropriate method that not only reduces mango decay but also maintains its postharvest quality.  The effects of chemicals, the use of the yeast species Metschnikowia pulcherrima and their combination on storage quality, focusing on the enzyme activity related to disease of Tainong mangos was studied.  By immersing the mangoes in M. pulcherrima suspension (1.0×108 cfu mL–1), salicylic acid (SA) solution (50 mg L–1) or calcium chloride (CaCl2) solution (1.0 g L–1), the lesion expansion and decay of the mango fruit caused by C. gloeosporioides could be significantly delayed.  These treatments also delayed the changes in quality traits (a* value, firmness, contents of total soluble solids (TSS) and vitamin C (Vc), while the activities of anti-disease enzymes such as polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), chitinase (CHT) and β-1,3-glucanase (GUN) were enhanced as compared to the control treatment.  Furthermore, the combination of SA solution, CaCl2 solution and M. pulcherrima suspension presented an additive effect, increasing the efficacy in controlling the disease and maintaining the storage quality of mango fruits.  Taken together, our data suggest that the integration of chemical treatments combined with M. pulcherrima could be an alternative to the use of fungicides in postharvest treatment of the mango fruit, specifically for improving storage quality as well as the control of the anthracnose.
    Short Communication
    Impacts of Sletr1-1 and Sletr1-2 mutations on the hybrid seed quality of tomatoes
    Syariful Mubarok, Hiroshi Ezura, Anas, Kusumiyati, Neni Rostini, Erni Suminar, Gungun Wiguna
    2019, 18(5): 1170-1176.  DOI: 10.1016/S2095-3119(19)62614-6
    Abstract ( )   PDF in ScienceDirect  
    Shelf life is an important breeding trait in tomato, especially for the tomato production in subtropical and tropical regions.  Previously we have isolated and characterized ethylene receptor mutants, Sletr1-1 and Sletr1-2 from mutant population based on Micro-Tom cultivar.  Sletr1-1 showed insensitivity to ethylene while Sletr1-2 showed reduced sensitivity to ethylene.  We also have demonstrated that the traits are useful for extending fruit shelf life of the hybrid tomato cultivars.  For commercializing the hybrid cultivars, the seed quality is another important trait.  In this study, we evaluated the effects of the Sletr1-1 and Sletr1-2 mutations on the seed quality characteristics of F1 hybrid lines generated by crossing Sletr1-1 and Sletr1-2 with three commercial tomato cultivars, Intan, Mutiara and Ratna.  Sletr1-1 mutation conferred insensitivity to ethylene in the F1 hybrid seedlings, resulting in negative effects including reduced germination rate, vigor index and emergence speed index.  Interestingly Sletr1-2 mutation had almost no effect on the seed quality characteristics of the F1 hybrid lines, suggesting that Sletr1-2 was suitable for producing high quality of hybrid seeds.