2020 Vol. 19 No. 1 Previous Issue    Next Issue

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

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    Prospects of utilization of inter-subspecific heterosis between indica and japonica rice
    ZHANG Gui-quan
    2020, 19(1): 1-10.  DOI: 10.1016/S2095-3119(19)62843-1
    Abstract ( )   PDF in ScienceDirect  
    The Asian cultivated rice (Oryza sativa L.) grown worldwide is divided into two subspecies, indica and japonica.  It is well known that the heterosis of inter-subspecies is usually stronger than that of intra-subspecies.  Since the 1970s, indica hybrid rice, an intra-subspecific hybrid rice, has being widely used in China and even in the world.  However, the inter-subspecific hybrid rice between indica and japonica is still unavailable.  The major obstacle is the hybrid sterility of the inter-subspecies.  In recent decades, the genetic and molecular basis of indica-japonica hybrid sterility was understood more and more clearly.  Some breeding approaches for overcoming inter-subspecific hybrid sterility were proposed and used to develop the indica-japonica hybrid rice.  The updated understanding will offer new approaches for development of breeding lines for overcoming indica-japonica hybrid sterility, which facilitates developing of inter-subspecific hybrid rice.
    Insights into African swine fever virus immunoevasion strategies
    WANG Jun, SHI xin-jin, SUN Hai-wei, CHEN Hong-jun
    2020, 19(1): 11-22.  DOI: 10.1016/S2095-3119(19)62762-0
    Abstract ( )   PDF in ScienceDirect  
    African swine fever (ASF) is an acute and highly contagious disease that causes severe economic losses to the swine industry.  ASF is caused by infection of African swine fever virus (ASFV) in domestic pigs, leading to almost 100% mortality.  However, no effective vaccines and pharmacologic treatment against ASF are available.  ASF poses a severe threat to the swine industry and the economy.  Here we summarize potential virus-host cell interaction mechanisms involving the suppression of innate and adaptive immune responses to ASFV entry and infection.  These mechanisms include modulation of apoptosis, inhibition of inflammatory responses, reduction of IFN production, inhibition of autophagy, and suppression of MHC-I expression.  Insights into immunoevasion strategies by ASFV may shed light on the development of vaccines, as well as preventive and therapeutic drugs.
    Crop Science
    Genetic and agronomic traits stability of marker-free transgenic wheat plants generated from Agrobacterium-mediated co-transformation in T2 and T3 generations
    LIU Hui-yun, WANG Ke, WANG Jing, DU Li-pu, PEI Xin-wu, YE Xing-guo
    2020, 19(1): 23-32.  DOI: 10.1016/S2095-3119(19)62601-8
    Abstract ( )   PDF in ScienceDirect  
    Genetically modified wheat has not been commercially utilized in agriculture largely due to regulatory hurdles associated with traditional transformation methods.  Development of marker-free transgenic wheat plants will help to facilitate biosafety evaluation and the eventual environmental release of transgenic wheat varieties.  In this study, the marker-free transgenic wheat plants previously obtained by Agrobacterium-mediated co-transformation of double T-DNAs vector were identified by fluorescence in situ hybridization (FISH) in the T1 generation, and their genetic stability and agronomic traits were analyzed in T2 and T3 generations.  FISH analysis indicated that the transgene often integrated into a position at the distal region of wheat chromosomes.  Furthermore, we show that the GUS transgene was stably inherited in the marker-free transgenic plants in T1 to T3 generations.  No significant differences in agronomic traits or grain characteristics were observed in T3 generation, with the exception of a small variation in spike length and grains per spike in a few lines.  The selection marker of bar gene was not found in the transgenic plants through T1 to T3 generations.  The results from this investigation lay a solid foundation for the potential application of the marker-free transgenic wheat plants achieved through the co-transformation of double T-DNAs vector by Agrobacterium in agriculture after biosafty evaluation.
    Biotic and abiotic stress-responsive genes are stimulated to resist drought stress in purple wheat
    LI Xiao-lan, Lü Xiang, WANG Xiao-hong, PENG Qin, ZHANG Ming-sheng, REN Ming-jian
    2020, 19(1): 33-50.  DOI: 10.1016/S2095-3119(19)62659-6
    Abstract ( )   PDF in ScienceDirect  
    Triticum aestivum L. cv. Guizi 1 (GZ1) is a drought-tolerant local purple wheat cultivar.  It is not clear how purple wheat resists drought stress, but it could be related to anthocyanin biosynthesis.  In this study, transcriptome data from drought-treated samples and controls were compared.  Drought slightly reduced the anthocyanin, protein and starch contents of GZ1 grains and significantly reduced the grain weight. Under drought stress, 16 682 transcripts were reduced, 27 766 differentially expressed genes (DEGs) were identified, and 379 DEGs, including DREBs, were related to defense response.  The defense-response genes included response to water deprivation, reactive oxygen, bacteria, fungi, etc.  Most of the structural and regulatory genes in anthocyanin biosynthesis were downregulated, with only TaDFR, TaOMT, Ta5,3GT, and TaMYB-4B1 being upregulated. TaCHS, TaF3H, TaCHI, Ta4CL, and TaF3’H are involved in responses to UV, hormones, and stimulus.  TaCHS-2D1, TaDFR-2D2, TaDFR-7D, TaOMT-5A, Ta5,3GT-1B1, Ta5,3GT-3A, and Ta5,3GT-7B1 connect anthocyanin biosynthesis with other pathways, and their interacting proteins are involved in primary metabolism, genetic regulation, growth and development, and defense responses.  There is further speculation about the defense-responsive network in purple wheat.  The results indicated that biotic and abiotic stress-responsive genes were stimulated to resist drought stress in purple wheat GZ1, and anthocyanin biosynthesis also participated in the drought defense response through several structural genes.
    Precision phenotyping of contrasting potato (Solanum tuberosum L.) varieties in a novel aeroponics system for improving nitrogen use efficiency: In search of key traits and genes
    Jagesh K. TIWARI, Sapna DEVI, Tanuja BUCKSETH, Nilofer ALI, Rajesh K. SINGH, Rasna ZINTA, Vijay K. DUA, Swarup K. CHAKRABARTI
    2020, 19(1): 51-62.  DOI: 10.1016/S2095-3119(19)62625-0
    Abstract ( )   PDF in ScienceDirect  
    With increasing population, degrading soil health, limited arable land area, and high cost of nitrogen (N) fertilizers, improving nitrogen use efficiency (NUE) of potato is an inevitable approach to save the environment and achieve sufficient tuber yields with less N fertilizer supply.  Recently, we have developed an aeroponics system to study NUE in potato using genomics, physiology, and breeding approaches.  This study aims on precision phenotyping of plants of two distinct potato varieties (Kufri Gaurav, N efficient; Kufri Jyoti, N inefficient) in the novel aeroponics system.  Plants were grown in aeroponics under controlled conditions with low N (0.75 mmol L–1 NO3) and high N (7.5 mmol L–1 NO3) levels.  Plant biomass, root traits, total chlorophyll content, and plant N were increased with increasing N supply, whereas higher NUE parameters namely NUE, agronomic NUE (AgNUE), N uptake efficiency (NUpE), harvest index (HI), and N harvest index (NHI) were observed at low N.  An NUE efficient cv. Kufri Gaurav showed higher tuber dry weight, fresh tuber yield, tuber number per plant, early start of tuber harvesting, root traits, stolon traits, NUE parameters, and higher amino acid (aspartic acid and asparagine) content at low N supply.  Higher expression of nitrate reductase (NR), nitrite reductase (NIR), and asparagine synthetase (AS) genes was observed in the leaf tissues of Kufri Gaurav at high N.  Thus, aeroponics-based precision phenotyping enables identification of NUE efficient genotypes based on key traits and genes involved in improving NUE in potato.  Further, this study suggests that the potential of aeroponics can be utilized to investigate N biology in potato under different N regimes.
    Effects of uniconazole with or without micronutrient on the lignin biosynthesis, lodging resistance, and winter wheat production in semiarid regions
    Irshad AHMAD, MENG Xiang-ping, Muhammad KAMRAN, Shahzad ALI, Shakeel AHMAD, LIU Tie-ning, CAI Tie, HAN Qing-fang
    2020, 19(1): 62-77.  DOI: 10.1016/S2095-3119(19)62632-8
    Abstract ( )   PDF in ScienceDirect  
    Lodging stress results in grain yield and quality reduction in wheat.  Uniconazole, a potential plant growth regulator significantly enhances lignin biosynthesis and thus provides mechanical strength to plants in order to cope with lodging stress.  A field study was conducted during the 2015–2016 and 2016–2017 growing seasons, to investigate the effects of uniconazole sole application or with micronutrient on the lignin biosynthesis, lodging resistance, and production of winter wheat.  In the first experiment, uniconazole at concentrations of 0 (CK), 15 (US1), 30 (US2), and 45 (US3) mg L–1 was applied as sole seed soaking, while in the second experiment with manganese (Mn) at concentration of 0.06 g L–1 Mn, 0.06 g L–1 Mn+15 mg L–1 uniconazole (UMS1), 0.06 g L–1 Mn+30 mg L–1 uniconazole (UMS2), and 0.06 g L–1 Mn+45 mg L–1 uniconazole (UMS3), respectively.  Uniconazole sole application or with micronutrient significantly increased the lignin content by improving the lignin-related enzyme activities of phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, tyrosine ammonia-lyase, and peroxidase, ameliorating basal internode characteristics, and breaking strength.  The spike length, spike diameter, spikes/plant, weight/spike, yield/spike, and grain yield increased and then decreased with uniconazole application at a higher concentration, where their maximum values were recorded with UMS2 and US2 treatments.  The lignin accumulation was positively correlated with lignin-related enzyme activities and breaking strength while, negatively correlated with lodging rate.  Uniconazole significantly improved the lignin biosynthesis, lodging resistance, and grain yield of winter wheat and the treatments which showed the greatest effects were uniconazole seed soaking with micronutrient at a concentration of 30 mg L–1 and 0.06 g L–1, and uniconazole sole seed soaking at a concentration of 30 mg L–1.
    Weakened carbon and nitrogen metabolisms under post-silking heat stress reduce the yield and dry matter accumulation in waxy maize
    YANG Huan, GU Xiao-tian, DING Meng-qiu, LU Wei-ping, LU Da-lei
    2020, 19(1): 78-88.  DOI: 10.1016/S2095-3119(19)62622-5
    Abstract ( )   PDF in ScienceDirect  
    Post-silking high temperature is one of the abiotic factors that affects waxy maize (Zea mays L. sinensis Kulesh) growth in southern China.  We conducted a pot trial in 2016–2017 to study the effects of post-silking daytime heat stress (35°C) on the activities of enzymes involved in leaf carbon and nitrogen metabolisms and leaf reactive oxygen species (ROS) and water contents.  This study could improve our understanding on dry matter accumulation and translocation and grain yield production.  Results indicated that decreased grain number and weight under heat stress led to yield loss, which decreased by 20.8 and 20.0% in 2016 and 2017, respectively.  High temperature reduced post-silking dry matter accumulation (16.1 and 29.5% in 2016 and 2017, respectively) and promoted translocation of pre-silking photoassimilates stored in vegetative organs, especially in leaf.  The lower leaf water content and chlorophyll SPAD value, and higher ROS (H2O2 and O2-·) content under heat stress conditions indicated accelerated senescent rate.  The weak activities of phosphoenolpyruvate carboxylase (PEPCase), Ribulose-1,5-bisphosphate carboxylase (RuBPCase), nitrate reductase (NR), and glutamine synthase (GS) indicated that leaf carbon and nitrogen metabolisms were suppressed when the plants suffered from a high temperature during grain filling.  Correlation analysis results indicated that the reduced grain yield was mainly caused by the decreased leaf water content, weakened NR activity, and increased H2O2 content.  The increased accumulation of grain weight and post-silking dry matter and the reduced translocation amount in leaf was mainly due to the increased chlorophyll SPAD value and NR activity.  Reduced PEPCase and RuBPCase activities did not affect dry matter accumulation and translocation and grain yield.  In conclusion, post-silking heat stress down-regulated the leaf NR and GS activities, increased the leaf water loss rate, increased ROS generation, and induced pre-silking carbohydrate translocation.  However, it reduced the post-silking direct photoassimilate deposition, ultimately, leading to grain yield loss.
    Physiological traits and anatomic structures of the seed for two short cotton season genotypes (Gossypium hirsutum L.) under water stress
    2020, 19(1): 89-98.  DOI: 10.1016/S2095-3119(19)62619-5
    Abstract ( )   PDF in ScienceDirect  
    Cotton (Gossypium hirsutum L.) is utilized commercially in the production of textile, clothing, and household goods.  Its growth is affected by various environmental conditions such as soil, climate, and water supply.  Irrigation is one of the most important factors for crop management.  This research was designed with the aim of studying the biochemical and anatomical features of two genotypes of cottonseed (Latif and Golestan) in order to determine optimum irrigation.  Protein, starch, gossypol gland, total soluble protein, starch content, and the anatomical structure of the cotton seeds were investigated.  The data were analyzed using the SAS Software.  The results showed that when rainfed, Golestan genotype seeds had a larger number of secretory cavities, soluble protein, and starch compared to Latif seeds.  There was also a noticeable difference in the size of the seeds.  Cellulosic cell walls and protein particles were also observed in the seed structure under induced water stress conditions.  It can therefore be concluded that in response to water shortage, there was a noticeable change in the morphometric, anatomic, and biochemical features of the cottonseeds.  It can be concluded that when rainfed, the Golestan genotype of cottonseed has more compatibility than the Latif genotype.  In general, the application of different levels of irrigation showed that at moderate levels of irrigation, anatomical features appeared more normal.  The observations indicate that at high levels of irrigation, some cells begin to dehisce due to osmotic stress, which results in a lack of accurate formation of tissue structures.  The Golestan genotype is therefore the best suited for dryland farming.
    Evaluation of drought indices to identify tolerant genotypes in common bean bush (Phaseolus vulgaris L.)
    Alefsi David SáNCHEZ-REINOSO, Gustavo Adolfo LIGARRETO-MORENO, Hermann RESTREPO-DíAZ
    2020, 19(1): 99-107.  DOI: 10.1016/S2095-3119(19)62620-1
    Abstract ( )  
    Drought is one of the major abiotic stresses often causing negative impacts on bean crops in the Andean region in Colombia.  An experiment under the greenhouse conditions was carried out to assess the effect of a prolonged drought period (15 days) at two different phenological stages (vegetative or reproductive) on grain yield and yield components of five bush bean cultivars (ICA-Cerinza, Bachue, NUA35, Bianca, and Bacatá).  Nine tolerance indices including stress susceptibility index (SSI), tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), yield stability index (YSI), yield index (YI), Harmonic mean (HM), and drought sensitivity index (DSI) were calculated based on grain yield under non-stressed (YP) and drought (YS) conditions.  Based on the different drought indices, genotypes ICA-Cerinza and NUA35 had the best performance under drought conditions in both studied phases, which reflected in a reduction of grain yield ~≤40%.  The biplot analysis also showed a clear superiority of these two genotypes at both phenological stages. Results also showed that SSI was more effective to identify genotypes less affected by drought.  The above results allowed us to conclude that ICA-Cerinza and NUA35 may be considered for agricultural areas where long periods of water deficit are expected and can be used in breeding programs for drought tolerance.
    Effects of different LEDs light spectrum on the growth, leaf anatomy, and chloroplast ultrastructure of potato plantlets in vitro and minituber production after transplanting in the greenhouse
    CHEN Li-li, ZHANG Kai, GONG Xiao-chen, WANG Hao-ying, GAO You-hui, WANG Xi-quan, ZENG Zhao-hai, HU Yue-gao
    2020, 19(1): 108-119.  DOI: 10.1016/S2095-3119(19)62633-X
    Abstract ( )   PDF in ScienceDirect  
    Light spectrum plays an important role in regulating the growth and development of in vitro cultured potato (Solanum tuberosum L.) plantlets.  The status of potato plantlets at the end of in vitro stage influences the minituber production after transplanting.  With 100 μmol m–2 s–1 total photosynthetic photon flux density (PPFD), a light spectrum study of 100% red light emitting diodes (LEDs) light spectrum (RR), 100% blue LEDs light spectrum (BB), 65% red+35% blue LEDs light spectrum (RB), and 45% red+35% blue+20% green LEDs light spectrum (RBG) providing illumination at the in vitro cultured stage of potato plantlets for 4 weeks using fluorescent lamp as control (CK) was performed to investigate the effects of LEDs light spectrum on the growth, leaf anatomy, and chloroplast ultrastructure of potato plantlets in vitro as well as the minituber yield after 2 months transplanting in the greenhouse.  Compared to CK, RB and RBG promoted the growth of potato plantlets in vitro with increased stem diameter, plantlet fresh weight, plantlet dry weight, and health index.  Furthermore, BB induced the greatest stem diameter as well as the highest health index in potato plantlets in vitro.  Root activity, soluble protein, and free amino acid were also significantly enhanced by BB, whereas carbohydrates were improved by RR.  In addition, thickness of leaf, palisade parenchyma and spongy parenchyma was significantly increased by BB and RBG.  Chloroplasts under BB and RBG showed well-developed grana thylakoid and stroma thylakoid.  Unexpectedly, distinct upper epidermis with greatest thickness was induced and palisade parenchyma and spongy parenchyma were arranged neatly in RR.  After transplanting in the greenhouse for 2 months, potato plantlets in vitro from BB, RB, and RBG produced high percentage of large size tuber.  BB improved fresh and dry weights of the biggest tuber but decreased tuber number per plantlet.  In addition, RBG increased tuber number as well as tuber fresh and dry weight slightly.  Our results suggested monochromatic blue LEDs as well as combined red, blue or/and green LEDs light spectrum were superior to fluorescent lamp spectrum in micro-propagation of potato plantlets.  Therefore, the application of RBG was suitable; BB and RB could be used as alternatives.
    Domestication and breeding changed tomato fruit transcriptome 
    LIU Dan, YANG Liang, ZHANG Jin-zhe, ZHU Guang-tao, Lü Hong-jun, Lü Ya-qing, WANG Yan-ling, CAO Xue, SUN Tian-shu, HUANG San-wen, WU Yao-yao
    2020, 19(1): 120-132.  DOI: 10.1016/S2095-3119(19)62824-8
    Abstract ( )   PDF in ScienceDirect  
    Tomato (Solanum lycopersicum) stress resistance and fruit total soluble solid (TSS) content have changed dramatically during selective breeding, and transcriptome variation has played a critical role in this rewiring.  However, the single tomato reference genome impedes characterization of whole-transcriptome variation during domestication and breeding at the population level.  Here, we constructed a pan-transcriptome of orange-stage tomato fruit, and investigated global expression presence/absence variation (ePAV) and differentially expressed genes (DEGs) based on RNA sequencing (RNA-seq) data from 399 tomato accessions.  A total of 7 181 genes absent from the reference genome were identified, 6 122 of which were ePAV genes during tomato domestication and breeding including resistance genes such as late blight resistance gene PIM_DN29746_c0_g3_i1 and peroxidase P7-like gene PIM_DN30274_c0_g2_i1.  In addition, 3 629 genes were significantly differentially expressed during tomato selection, among which 19 genes were associated with the reduced fruit TSS content of modern tomato cultivars, including LIN5, TIV1, and seven novel sugar transporter genes.  Our results indicate that natural and artificial selection greatly shaped the tomato transcriptome, thereby altering the fruit TSS content and resistance to abiotic and biotic stresses.
    Selenium distribution and nitrate metabolism in hydroponic lettuce (Lactuca sativa L.): Effects of selenium forms and light spectra
    BIAN Zhong-hua, LEI Bo, CHENG Rui-feng, WANG Yu, LI Tao, YANG Qi-chang
    2020, 19(1): 133-144.  DOI: 10.1016/S2095-3119(19)62775-9
    Abstract ( )   PDF in ScienceDirect  
    A deficiency in selenium (Se) in the human diet is a worldwide problem.  The intake of Se-rich vegetables can be a safe way to combat Se deficiency for humans.  However, most leafy vegetables can accumulate a high content of nitrates, which poses a potential threat to human health.  Light is an important environmental factor that regulates the uptake and distribution of mineral elements and nitrogen metabolism in plants.  However, the effects of Se forms and light conditions, especially light spectra, on the uptake and translocation of Se and on nitrate reduction are poorly understood.  In this study, lettuce (Lactuca sativa L.) was treated with exogenous Se applied as selenate (10 mmol L–1) and selenite (0.5 mmol L–1) and grown under five different light spectra: fluorescent light (FL), monochromatic red LED light (R), monochromatic blue LED light (B), and mixed red and blue LED light with a red to blue light ratio at 4 (R/B=4), 8 (R/B=8), and 12 (R/B=12), respectively.  The effects of light spectra and Se forms on plant growth, photosynthetic performance, Se accumulation and nitrate reduction were investigated.  The results showed that the light spectra and Se forms had significant interactions for plant growth, foliar Se accumulation and nitrate reduction.  The Se concentration and nitrate content in the leaves were negatively correlated with the percentage of red light from the light sources.  Compared to Se applied as selenite, exogenous Se applied as selenate was more effective in reducing nitrate via promoting nitrate reductase and glutamate synthase activities.  The lowest nitrate content and highest plant biomass were observed under R/B=8 for both the selenate and selenite treatments.  The significant effect of the light spectra on the root concentration factor and translocation factor of Se resulted in marked variations in the Se concentrations in the roots and leaves.  Compared with FL, red and blue LED light led to significant decreases in the foliar Se concentration.  The results from this study suggest that the light spectra can contribute to Se distribution and accumulation to produce vegetables with better food quality. 
    Plant Protection
    Screening of antagonistic Trichoderma strains and their application for controlling stalk rot in maize 
    LU Zhi-xiang, TU Guang-ping, ZHANG Ting, LI Ya-qian, WANG Xin-hua, Zhang Quan-guo, SONG Wei, CHEN Jie
    2020, 19(1): 145-152.  DOI: 10.1016/S2095-3119(19)62734-6
    Abstract ( )   PDF in ScienceDirect  
    Maize is one of the major crops in China, but maize stalk rot occurs nationwide and has become one of the major challenges in maize production in China.  In order to find an environment-friendly and feasible technology to control this disease, a Trichoderma-based biocontrol agent was selected.  Forty-eight strains with various inhibition activities to Fusarium graminearum, and Fusarium verticillioides were tested.  A group of Trichoderma strains (DLY31, SG3403, DLY1303 and GDFS1009) were found to provide an inhibition rate to pathogen growth in vitro of over 70%.  These strains also prevented pathogen infection over 65% and promoted the maize seedling growth for the main root in vivo by over 50%.  Due to its advantage in antifungal activity against pathogens and promotion activity to maize, Trichoderma asperellum GDSF1009 was selected as the most promising strain of the biocontrol agent in the Trichoderma spectrum.  Pot experiments showed that the Trichoderma agent at 2–3 g/pot could achieve the best control of seedling stalk rot and promotion of maize seedling growth.  In the field experiments, 8–10 g/hole was able to achieve over 65% control to stalk rot, and yield increased by 2–11%.  In the case of natural morbidity, the control efficiency ranged from 27.23 to 48.84%, and the rate of yield increase reached 11.70%, with a dosage of Trichoderma granules at 75 kg ha–1.  Based on these results, we concluded that the Trichoderma agent is a promising biocontrol approach to stalk rot in maize.
    Mapping subgenomic promoter of coat protein gene of Cucumber green mottle mosaic virus
    LIU Mei, LIU Li-ming, WU Hui-jie, KANG Bao-shan, GU Qin-sheng
    2020, 19(1): 153-163.  DOI: 10.1016/S2095-3119(19)62647-X
    Abstract ( )   PDF in ScienceDirect  
    Many plant viruses utilize subgenomic RNA as gene expression strategy, therefore mapping subgenomic promoter (SGP) is extremely important for constructing viral vectors.  Although Cucumber green mottle mosaic virus (CGMMV)-based virus vectors have been constructed, SGP of the coat protein (CP) has not yet mapped.  To this end, we firstly presumed 13 nucleotides upstream of the start codon as the transcription starting site (TSS) as previous study identified by random amplification of cDNA ends (RACE).  Secondly, the region from nucleotides –110 to +175 is the putative CP SGP, as predicted, a long stem loop structure by the secondary structure of RNA covering movement protein (MP) and CP.  To map the CGMMV CP SGP, we further constructed a series of deletion mutants according to RNA secondary structure prediction.  The deletion of TSS upstream significantly enhanced CP transcription when 105 nucleotides were retained before the CP TSS.  For the downstream of CP TSS, we analyzed the expression of enhanced green fluorescent protein (EGFP) in a series of vectors with partial deletion of the CGMMV CP and found that the nucleotides from +71 to +91 played a key role in the EGFP expression at the transcription level, while EGFP showed the highest expression level when 160 nucleotides were retained downstream of the CP TSS.  To confirm these results, we applied online software MEME to predict the motifs and cis-acting elements in the 466 nucleotides covering the sequences of deletion analysis.  Conserved motifs and relative acting elements were in regions in which transcription levels were the highest or enhanced.  To our best knowledge, this is the first mapping of CGMMV SGP.
    Evaluation of soil flame disinfestation (SFD) for controlling weeds, nematodes and fungi
    WANG Xiao-ning, CAO Ao-cheng, YAN Dong-dong, WANG Qian, HUANG Bin, ZHU Jia-hong, WANG Qiu-xia, LI Yuan, OUYANG Can-bin, GUO Mei-xia, WANG Qian
    2020, 19(1): 164-172.  DOI: 10.1016/S2095-3119(19)62809-1
    Abstract ( )   PDF in ScienceDirect  
    Soil flame disinfestation (SFD) is a form of physical disinfestation that can be used both in greenhouses and on field crops.  Its use for soil disinfestation in different crop growing conditions makes it increasingly attractive for controlling soil-borne pathogens and weeds.  But little is known about the effect on weeds and soilbrone diseases.  This study reports on greenhouses and field crops in China that determined the efficacy of SFD to control weeds, nematodes and fungi.  It also determined the impact of SFD on the soil physical and chemical properties (water content, bulk density, NO3-N content, NH4+-N content, conductivity and organic matter) in three field trials.  A second generation SFD machine was used in these trials.  SFD treatment significantly reduced weeds (>87.8%) and root-knot nematodes (Meloidogyne incognita) (>98.1%).  Plant height and crop yield was significantly increased with SFD treatment.  NO3-N and NH4+-N increased after the SFD treatment, and there was also an increase in soil conductivity.  Water content, bulk density and organic matter decreased significantly in the soil after the SFD treatment compared to the control.  Soil flame disinfestation is a potential technique for controlling weeds and diseases in greenhouses or in fields.  SFD is a non-chemical, safe, environmentally-friendly soil disinfection method. 
    Herbicidal activity of Aureobasidium pullulans PA-2 on weeds and optimization of its solid-state fermentation conditions
    GUO Qing-yun, CHENG Liang, ZHU Hai-xia, LI Wei, WEI You-hai, CHEN Hong-yu, GUO Liang-zhi, WENG Hua, WANG Jian
    2020, 19(1): 173-182.  DOI: 10.1016/S2095-3119(19)62738-3
    Abstract ( )   PDF in ScienceDirect  
    Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China.  Based on the culture characteristics and the internal transcribed spacer (ITS) sequence of its 16S rDNA, the strain was identified as Aureobasidium pullulans.  The culture and metabolites of strain PA-2 showed high herbicidal potential to five tested weeds Galium aparine var. tenerum, Chenopodium album, Malva crispa, Polygonum lapathifolium and Avena fatua.  For the in vitro test, 5 days after the detached leaves were inoculated with PA-2 culture, all leaves infected by the hyphae and became black and rotten.  For the in vivo test, a metabolite filtrate of PA-2 culture was sprayed over the living weed plants, and five days after inoculation, the weed plants became withered and necrotic.  Seven days after inoculation, the fresh weight reductions of G. aparine var. tenerum, C. album, M. crispa, P.?lapathifolium and A.?fatua were 87.25, 78.46, 82.25, 62.11, and 80.27%, respectively.  Galium aparine var. tenerum and M. crispa exhibited significant reductions in fresh weight.  The bio-safety test on the five crops showed no significant plant height reductions, which was also observed for wheat (Triticum aestivum), faba bean (Vicia faba), and barley (Hordeum vulgare).  By contrast, oilseed rape (Brassica napus) and pea (Pisum sativum) exhibited light spots but no significant reductions in plant height.  These results indicated that A.?pullulans could be a potential microbial herbicide for the control of the target weeds in crops.  Optimization of the carbon and nitrogen sources for cultural media and substances for solid-state fermentation indicated that PA-2 had better colony growth and spore production with the optimal carbon source of glucose (C4), nitrogen source of soybean flour (N2), and the optimal substance was wheat bran.  The results in this study provide useful information for the development of A.?pulluans PA-2 as an herbicide for bio-control of the weed.
    Identification and characterization of a TLR13 gene homologue from Laodelphax striatellus involved in the immune response induced by rice stripe virus
    ZHOU Xue, HU Jia, FU Mei-li, JIN Ping, ZHANG Yun-ye, XIANG Ying, LI Yao, MA Fei
    2020, 19(1): 183-192.  DOI: 10.1016/S2095-3119(19)62795-4
    Abstract ( )   PDF in ScienceDirect  
    Toll-like receptors (TLRs) are the critical superfamily homologues that initiate sensing of the invasion of pathogens by the Toll pathway.  As one of several intracellular nucleic acid-sensing TLRs, TLR13 is activated by an unmethylated motif present in the large ribosomal subunit of bacterial RNA.  However, little attention has been paid to the function of TLR13 gene homologue from Laodelphax striatellus (designated as LsToll-13) in the immune response to rice stripe virus (RSV).  Herein, LsToll-13 was cloned and characterized using RACE-PCR.  Phylogenetic analysis showed that LsToll-13 was clustered with the TLR13 from six insects.  Real-time PCR analysis demonstrated that the expression level of LsToll-13 was significantly reduced in L.?striatellus with RSV infection compared with that in the naive strain.  When the expression of LsToll-13 was significantly up-regulated at 6 h after bacterial infection, the expression of ribonucleoprotein (RNP) indicated that the RSV titer in the host insect was significantly suppressed.  Upon knockdown of LsToll-13, using RNA interference (RNAi) in L.?striatellus, the expression level of RNP was significantly increased with enhanced RSV accumulation, suggesting that LsToll-13 potentially protects L.?striatellus from RSV infection.  Taken together, our results indicated that LsToll-13 might be involved in the immune response of L.?striatellus to RSV infection, and provided a new insight into further elucidating the molecular mechanisms of complex pathogen-host interactions and integrative pest management.
    Exploiting push-pull strategy to combat the tea green leafhopper based on volatiles of Lavandula angustifolia and Flemingia macrophylla
    HAN Shan-jie, WANG Meng-xin, WANG Yan-su, WANG Yun-gang, CUI Lin, HAN Bao-yu
    2020, 19(1): 193-203.  DOI: 10.1016/S2095-3119(19)62778-4
    Abstract ( )   PDF in ScienceDirect  
    Thirteen volatile compounds were identified from Flemingia macrophylla plants.  Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F.  Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, MeSA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL–1 in n-hexane, respectively; 2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL–1 in n-hexane, respectively; 3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and MeSA at 2, 10, 10 and 11 mg mL–1 in n-hexane, respectively.  Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL–1.  For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps.  The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards.  Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components.  When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day.  Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1 (43%) to day 5 (73%).  This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers. 
    Effects of Paranosema locustae (Microsporidia) on the development and morphological phase transformation of Locusta migratoria (Orthoptera: Acrididae) through modulation of the neurotransmitter taurine
    LI Ao-mei, YIN Yue, ZHANG Yu-xin, ZHANG Liu, ZHANG Kai-qi, SHEN Jie, TAN Shu-qian, SHI Wang-peng
    2020, 19(1): 204-210.  DOI: 10.1016/S2095-3119(19)62637-7
    Abstract ( )   PDF in ScienceDirect  
    Neurotransmitters are important in the maintenance of phase transformation of Locusta migratoria (Arthropoda: Orthoptera).  Here, the effects of the entomopathogen Paranosema locustae on the neurotransmitter taurine in migratory locusts were studied using biochemical methods.  After inoculation with P. locustae, the taurine content of infected locusts significantly declined, but F/C values (ratio between the length of hind femur and the width of the head of locust) increased significantly, compared to healthy locusts.  Meanwhile, F/C values of infected locusts that were injected with 2 µg of taurine showed no significant differences from those of healthy locusts, demonstrating that supplemental taurine inhibited the changes in morphological phase caused by P. locustaeParanosema locustae infection also caused longer developmental durations and lower body weights of locusts, but these changes were unaffected after injection with taurine.  These results provided new insights into the mechanisms by which microsporidian parasites affected their locust hosts.
    Animal Science · Veterinary Medicine
    The toxicological effect of dietary excess of saccharicterpenin, the extract of camellia seed meal, in piglets
    WANG Man, YU Bing, HE Jun, YU Jie, LUO Yu-heng, LUO Jun-qiu, MAO Xiang-bin, CHEN Dai-wen
    2020, 19(1): 211-224.  DOI: 10.1016/S2095-3119(19)62789-9
    Abstract ( )   PDF in ScienceDirect  
    Recently, saccharicterpenin extracted from Camellia oleifera seed meal has become a widely used feed supplement in animal husbandry.  In order to assess its safety, this study was designed to investigate the toxicity and histopathological effects of saccharicterpenin on piglets.  One hundred-fifty weaned pigs ((Yorkshire×Landrace)×Duroc), 75 males and 75 females with body weight (BW) of (7.35±0.29) kg, were randomly allotted to groups receiving diets supplemented with 0, 500, 1 000, 2 500 or 5 000 mg kg–1 saccharicterpenin for 70 d.  The diet with 500 mg kg–1 saccharicterpenin supplementation improved liver glutathione peroxidase (GSH-Px) activity, and the diet with 1 000 mg kg–1 saccharicterpenin supplementation improved liver glutathione S-transferase (GSH-S) activity in piglets on d 70 (P<0.05).  At 2 500 mg kg–1, saccharicterpenin in the diets reduced average daily feed intake (ADFI) and average daily gain (ADG) of piglets from d 1 to 35, damaged the cardiac tissue and liver on d 35, and decreased white blood cell counts (WBC), activities of catalase (CAT) and GSH-Px, and concentrations of glucose (GLU) and urea nitrogen (BUN) in the blood of piglets on d 70 (P<0.05).  In addition, diets with 5 000 mg kg–1 saccharicterpenin supplementation reduced ADFI, ADG and increased diarrhea rates of piglets from d 36 to 70, and decreased hemoglobin (HGB) concentration and activity of CAT in the blood of piglets on d 70 (P<0.05).  Moreover, at a rate of 5 000 mg kg–1, saccharicterpenin supplementation increased pancreas index on d 35 and hepatic index on d 70, and damaged cardiac tissue, liver and spleen during the whole experimental period (P<0.05).  These results suggested that dietary 500 mg kg–1 saccharicterpenin supplementation had beneficial effects on piglets, but excessive supplementation
    (2 500 or 5 000 mg kg–1) of saccharicterpenin in the diets could lead to growth retardation, hematological abnormalities and organ injuries.
    MicroRNA-22 inhibits proliferation and promotes differentiation of satellite cells in porcine skeletal muscle
    Hong Quyen Dang, XU Gu-li, HOU Lian-jie, XU Jian, HONG Guang-liang, Chingyuan Hu, WANG Chong
    2020, 19(1): 225-233.  DOI: 10.1016/S2095-3119(19)62701-2
    Abstract ( )   PDF in ScienceDirect  
    Pig is an important economic animal in China.  Improving meat quality and meat productivity is a long time issue in animal genetic breeding.  MicroRNAs (miRNAs) are short non-coding RNAs that participate in various biological processes, such as muscle development and embryogenesis.  miR-22 differentially expresses in embryonic and adult skeletal muscle.  However, the underlying mechanism is unclear.  In this study, we investigated miR-22 function in proliferation and differentiation of porcine satellite cells (PSCs) in skeletal muscle.  Our data show that miR-22 expressed in both proliferation and differentiated PSCs and is significantly upregulated (P<0.05) during differentiation.  After treated with the miR-22 inhibitor, PSCs proliferation was significantly increased (P<0.05), as indicated by the up-regulation (P<0.01) of cyclin D1 (CCND1), cyclin B1 (CCNB1) and down-regulation (P<0.05) of P21.  Conversely, over-expression of miR-22 resulted in opposite results.  Differentiation of PSCs was significantly suppressed (P<0.05), evidenced by two major myogenic markers: myogenin (MyoG) and myosin heavy chain (MyHC), after transfecting the PSCs with miR-22 inhibitor.  Opposite results were demonstrated in the other way around by transfection with miR-22 mimics.  In conclusion, the data from this study indicated that miR-22 inhibited the PSCs proliferation but promoted their differentiation. 
    Agro-ecosystem & Environment
    Effects of reduced nitrogen and suitable soil moisture on wheat (Triticum aestivum L.) rhizosphere soil microbiological, biochemical properties and yield in the Huanghuai Plain, China
    ZHOU Su-mei, ZHANG Man, ZHANG Ke-ke, YANG Xi-wen, HE De-xian, YIN Jun, WANG Chen-yang
    2020, 19(1): 234-250.  DOI: 10.1016/S2095-3119(19)62697-3
    Abstract ( )   PDF in ScienceDirect  
    Soil management practices affect rhizosphere microorganisms and enzyme activities, which in turn influence soil ecosystem processes. The objective of this study was to explore the effects of different nitrogen application rates on wheat (Triticum aestivum L.) rhizosphere soil microorganisms and enzyme activities, and their temporal variations in relation to soil fertility under supplemental irrigation conditions in a fluvo-aquic region. For this, we established a split-plot experiment for two consecutive years (2014–2015 and 2015–2016) in the field with three levels of soil moisture: water deficit to no irrigation (W1), medium irrigation to (70±5)% of soil relative moisture after jointing stage (W2), and adequate irrigation to (80±5)% of soil relative moisture after jointing stage (W3); and three levels of nitrogen: 0 kg ha–1 (N1), 195 kg ha–1 (N2) and
    270 kg ha–1 (N3).  Results showed that irrigation and nitrogen application significantly increased rhizosphere microorganisms and enzyme activities.  Soil microbiological properties showed different trends in response to N level; the highest values of bacteria, protease, catalase and phosphatase appeared in N2, while the highest levels of actinobacteria, fungi and urease were observed in N3.  In addition, these items performed best under medium irrigation (W2) relative to W1 and W3; particularly the maximum microorganism (bacteria, actinobacteria and fungi) amounts appeared at W2, 5.37×107 and 6.35×107 CFUs g–1 higher than those at W3 in 2014–2015 and 2015–2016, respectively; and these changes were similar in both growing seasons.  Microbe-related parameters fluctuated over time but their seasonality did not hamper the irrigation and fertilization-induced effects.  Further, the highest grain yields of 13 309.2 and 12 885.7 kg ha–1 were both obtained at W2N2 in 2014–2015 and 2015–2016, respectively.  The selected properties, soil microorganisms and enzymes, were significantly correlated with wheat yield and proved to be valuable indicators of soil quality.  These results clearly demonstrated that the combined treatment (W2N2) significantly improved soil microbiological properties, soil fertility and wheat yield on the Huanghuai Plain, China.
    Silicon impacts on soil microflora under Ralstonia Solanacearum inoculation
    LIN Wei-peng, JIANG Ni-hao, PENG Li, FAN Xue-ying, GAO Yang, WANG Guo-ping, CAI Kun-zheng
    2020, 19(1): 251-264.  DOI: 10.1016/S2095-3119(18)62122-7
    Abstract ( )   PDF in ScienceDirect  
    Silicon (Si) can increase plant resistance against bacterial wilt caused by Ralstonia solanacearum and enhance plant immune response.  However, whether Si alleviates soil-borne disease stress through altering soil microbial community component and diversity is not clear.  In this study, effects of Si application under R. solanacearum inoculation with or without plant on soil bacterial and fungal communities were investigated through high-throughput pyrosequencing technique.  The results showed that Si addition significantly reduced bacterial wilt incidence.  However, Si did not reduce the amount of R. solanacearum in rhizosphere soil.  Principal components analysis showed that soil microbial community composition was strongly influenced by Si addition.  Total 63.7% bacterial operational taxonomic units (OTUs) and 43.8% fungal OTUs were regulated by Si addition regardless of the presence of tomato plants, indicating the independent effects of Si on soil microbial community.  Si-added soil harbored a lower abundance of Fusarium, Pseudomonas, and Faecalibacterium.  Our finding further demonstrated that exogenous Si could significantly influence soil microbial community component, and this may provide additional insight into the mechanism of Si-enhanced plant resistance against soil-borne pathogens.
    Straw layer burial to alleviate salt stress in silty loam soils: Impacts of straw forms
    ZHANG Hong-yuan, LU Chuang, PANG Huan-cheng, LIU Na, ZHANG Xiao-li, LI Yu-yi
    2020, 19(1): 265-276.  DOI: 10.1016/S2095-3119(19)62737-1
    Abstract ( )   PDF in ScienceDirect  
    Salt stress can be alleviated by straw layer burial in the soil, but little is known of the appropriate form of the straw layer for optimal regulation of soil water and salinity because of the uncontrollability of field tests.  Here, the following four straw forms with compaction thickness of 5 cm buried 40–45 deep were studied: no straw layer (CK), segmented straw (SL, 5 cm in length), straw pellet (SK), and straw powder (SF).  The three straw forms (SL, SK and SF) significantly delayed the infiltration of irrigation water down the column profile by 71.20–134.3 h relative to CK and the migration velocity of the wetting front under SF was the slowest.  It took longer for the wetting front to transcend SK than SL but shorter for it to reach the bottom of soil column after water crossed the straw layer.  Compared with CK, the average volumetric water content in the 0–40 cm soil layer increased by 6.45% under SL, 1.77% under SK and 5.39% under SF.  The desalination rates at the 0–40 and 0–100 cm soil layers increased by 5.85 and 3.76% under SL, 6.64 and 1.47% under SK and 5.97 and 4.82% under SF.  However, there was no significant difference among straw forms in the 0–40 cm soil layer.  Furthermore, the salt leaching efficiency (SLE, g mm–1 h–1) above the 40 cm layer under SL was 0.0097, being significantly higher than that under SF (0.0071) by 37.23%.  Salt storage under SL, SK and SF in the 40–45 cm layer accounted for 4.50, 16.92 and 7.43% of total storage in the 1-m column profile.  Cumulative evaporation under SL and SF decreased significantly by 41.20 and 49.00%, with both treatments having the most significant inhibition of salt accumulation (resalinization rate being 36.06 and 47.15% lower than CK) in the 0–40 cm soil layer.  In conclusion, the different forms of straw layers have desalting effects under high irrigation level (446 mm).  In particular, SL and SF performed better than SK in promoting deep salt leaching and inhibiting salt accumulation on the soil surface.  However, SL was simpler to implement and its SLE was higher.  Therefore, the segmented 5 cm straw can be recommended as an optimum physical form for establishing a straw layer for managing saline soils for crop production.
    Soil temperature estimation at different depths, using remotely-sensed data
    HUANG Ran, HUANG Jian-xi, ZHANG Chao, MA Hong-yuan, ZHUO Wen, CHEN Ying-yi, ZHU De-hai, Qingling WU, Lamin R. MANSARAY
    2020, 19(1): 277-290.  DOI: 10.1016/S2095-3119(19)62657-2
    Abstract ( )   PDF in ScienceDirect  
    Soil temperatures at different depths down the soil profile are important agro-meteorological indicators which are necessary for ecological modeling and precision agricultural activities.  In this paper, using time series of soil temperature (ST) measured at different depths (0, 5, 10, 20, and 40 cm) at agro-meteorological stations in northern China as reference data, ST was estimated from land surface temperature (LST) and normalized difference vegetation index (NDVI) derived from AQUA/TERRA MODIS data, and solar declination (Ds) in univariate and multivariate linear regression models.  Results showed that when daytime LST is used as predictor, the coefficient of determination (R2) values decrease from the 0 cm layer to the 40 cm layer.  Additionally, with the use of nighttime LST as predictor, the R2 values were relatively higher at 5, 10 and 15 cm depths than those at 0, 20 and 40 cm depths.  It is further observed that the multiple linear regression models for soil temperature estimation outperform the univariate linear regression models based on the root mean squared errors (RMSEs) and R2.  These results have demonstrated the potential of MODIS data in tandem with the Ds parameter for soil temperature estimation at the upper layers of the soil profile where plant roots grow in.  To the best of our knowledge, this is the first attempt at the synergistic use of
    Moving beyond the opposition of diverse knowledge systems for food security and nutrition
    Nathana?l PINGAULT, Patrick CARON, Alicia KOLMANS, Stefanie LEMKE, Carol KALAFATIC, Sabine ZIKELI, Ann WATERS-BAYER, Carolin CALLENIUS, QIN Yong-jun
    2020, 19(1): 291-293.  DOI: 10.1016/S2095-3119(19)62807-8
    Abstract ( )   PDF in ScienceDirect  
    Food Security and Nutrition (FSN) is influenced by diverse and complex factors, and therefore requires a holistic approach to agriculture and food systems plus integration of knowledge from diverse sources in science and society.  Using the results of a colloquium held at the University of Hohenheim (Germany) in September 2016 leading up to the recent High Level Panel of Experts (HLPE) Note on Critical and Emerging Issues for Food Security and Nutrition, this article underlines the role of research and innovation as a social and political process and draws attention to neglected types of knowledge.  It illustrates the potential of knowledge co-production and co-innovation to transform food systems in order to achieve the Sustainable Development Goals.