2020 Vol. 19 No. 5 Previous Issue    Next Issue

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

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    Crop Science
    Identification of long-grain chromosome segment substitution line Z744 and QTL analysis for agronomic traits in rice
    MA Fu-ying, DU Jie, WANG Da-chuan, WANG Hui, ZHAO Bing-bing, HE Guang-hua, YANG Zheng-lin, ZHANG Ting, WU Ren-hong, ZHAO Fang-ming
    2020, 19(5): 1163-1169.  DOI: 10.1016/S2095-3119(19)62751-6
    Abstract ( )   PDF in ScienceDirect  
    Length of grain affects the appearance, quality, and yield of rice.  A rice long-grain chromosome segment substitution line Z744, with Nipponbare as the recipient parent and Xihui 18 as the donor parent, was identified.  Z744 contains a total of six substitution segments distributed on chromosomes (Chrs.) 1, 2, 6, 7, and 12, with an average substitution length of 2.72 Mb.  The grain length, ratio of length to width, and 1 000-grain weight of Z744 were significantly higher than those in Nipponbare.  The plant height, panicle number, and seed-set ratio in Z744 were significantly lower than those in Nipponbare, but they were still 78.7 cm, 13.5 per plant, and 86.49%, respectively.  Furthermore, eight QTLs of different traits were identified in the secondary F2 population, constructed by Nipponbare and Z744 hybridization.  The grain weight of Z744 was controlled by two synergistic QTLs (qGWT1 and qGWT7) and two subtractive QTLs (qGWT2 and qGWT6), respectively.  The increase in the grain weight of Z744 was caused mainly by the increase in grain length.  Two QTLs were detected, qGL1 and qGL7-3, which accounted for 25.54 and 15.58% of phenotypic variation, respectively.  A Chi-square test showed that the long-grain number and the short-grain number were in accordance with the 3:1 separation ratio, which indicates that the long grain is dominant over the short-grain and Z744 was controlled mainly by the principal effect qGL1.  These results offered a good basis for further fine mapping of qGL1 and further dissection of other QTLs into single-segment substitution lines.
    Bioinformatic identification and analyses of the non-specific lipid transfer proteins in wheat
    FANG Zheng-wu, HE Yi-qin, LIU Yi-ke, JIANG Wen-qiang, SONG Jing-han, WANG Shu-ping, MA Dong-fang, YIN Jun-liang
    2020, 19(5): 1170-1185.  DOI: 10.1016/S2095-3119(19)62776-0
    Abstract ( )   PDF in ScienceDirect  
    Non-specific lipid transfer proteins (nsLTPs/LTPs) that can transport various phospholipids across the membrane in vitro are widespread in the plant kingdom, and they play important roles in many biological processes that are closely related to plant growth and development.  Recently, nsLTPs have been shown to respond to different forms of abiotic stresses.  Despite the vital roles of nsLTPs in many plants, little is known about the nsLTPs in wheat.  In this study, 330 nsLTP proteins were identified in wheat and they clustered into five types (1, 2, c, d, and g) by phylogenetic analysis with the nsLTPs from maize, Arabidopsis, and rice.  The wheat nsLTPs of type d included three subtypes (d1, d2, and d3) and type g included seven subtypes (g1–g7).  Genetic structure and motif pattern analyses showed that members of each type had similar structural composition.  Moreover, GPI-anchors were found to exist in non-g type members from wheat for the first time.  Chromosome mapping revealed that all five types were unevenly and unequally distributed on 21 chromosomes.  Furthermore, gene duplication events contributed to the proliferation of the nsLTP genes.  Large-scale data mining of RNA-seq data covering multiple growth stages and numerous stress treatments showed that the transcript levels of some of the nsLTP genes could be strongly induced by abiotic stresses, including drought and salinity, indicating their potential roles in mediating the responses of the wheat plants to these abiotic stress conditions.  These findings provide comprehensive insights into the nsLTP family members in wheat, and offer candidate nsLTP genes for further studies on their roles in stress resistance and potential for improving wheat breeding programs.
    Development and identification of glyphosate-tolerant transgenic soybean via direct selection with glyphosate
    GUO Bing-fu, HONG Hui-long, HAN Jia-nan, ZHANG Li-juan, LIU Zhang-xiong, GUO Yong, QIU Li-juan
    2020, 19(5): 1186-1196.  DOI: 10.1016/S2095-3119(19)62747-4
    Abstract ( )   PDF in ScienceDirect  
    Glyphosate-tolerant soybean is the most widely planted genetically modified crop worldwide.   However, soybean remains recalcitrant to routine transformation because of the low infection efficiency of Agrobacterium to soybean and lack of useful selectable markers.  In this study, several Agrobacterium strains and cell densities were compared by transient expression of the GUS gene.  The results showed that Agrobacterium strain Ag10 at cell densities of OD600 of 0.6–0.9 yielded the highest infection efficiency in Agrobacterium-mediated soybean cotyledonary node transformation system.  Meanwhile, a simple and rapid method was developed for identification of glyphosate tolerance in putative T0 transgenic plants, consisting of spotting plantlets with 1 µL Roundup®.  The whole cycle of genetic transformation could be shortened to about 3 mon by highly efficient selection with glyphosate during the transformation process and application of the spot assay in putative T0 transgenic plantlets.  The transformation frequency ranged from 2.9 to 5.6%.  This study provides an improved protocol for development and identification of glyphosate-tolerant transgenic soybeans.
    Effect of wide-narrow row arrangement in mechanical pot-seedling transplanting and plant density on yield formation and grain quality of japonica rice
    HU Qun, JIANG Wei-qin, QIU Shi, XING Zhi-peng, HU Ya-jie, GUO Bao-wei, LIU Guo-dong, GAO Hui, ZHANG Hong-cheng, WEI Hai-yan
    2020, 19(5): 1197-1214.  DOI: 10.1016/S2095-3119(19)62800-5
    Abstract ( )   PDF in ScienceDirect  
    Mechanical pot-seedling transplanting is an innovatively developed transplanting method that has the potential to replace mechanical carpet-seedling transplanting.  However, the initial pot-seedling transplanting machine lacked optimized density spacing and limited yield potential for japonica rice.  Therefore, ascertaining the optimized density by wide-narrow rows and the appropriate transplanting method for yield formation and grain quality of japonica rice is of great importance for high-quality rice production.  Field experiments were conducted using two japonica rice cultivars Nanjing 9108 and Nanjing 5055 under three transplanting methods in 2016 and 2017: mechanical pot-seedling transplanting with wide-narrow row (K, average row spacing of 30 cm); equidistant row (D, 33 cm×12 cm); and mechanical carpet-seedling transplanting (T, 30 cm×12.4 cm).  In addition, five different density treatments were set in K (K1–K5, from 18.62×104 to 28.49×104 hills ha–1).  The results showed that the highest yield was produced by a planting density of 26.88×104 hills ha–1 in mechanical pot-seedling transplanting with wide-narrow row with a greater number of total spikelets that resulted from significantly more panicles per area and slightly more grain number per panicle, as compared with equidistant row, and yield among density in wide-narrow row showed a parabolic trend.  Compared with mechanical carpet-seedling transplanting, the treatment of the highest yield increased yield significantly, which was mainly attributed to the larger sink size with improved filled-grain percentage and grain weight, higher harvest index, and increased total dry matter accumulation, especially the larger amount accumulated from heading stage to maturity stage.  With the density in wide-narrow row decreasing, processing quality, appearance quality, and nutrition quality were all improved, whereas amylose content and the taste value were decreased.  Compared with mechanical carpet-seedling transplanting, mechanical pot-seedling transplanting improved processing quality and nutrition quality, but decreased amylose content and deteriorated appearance quality.  These results suggested that mechanical pot-seedling transplanting with wide-narrow row coupling produced a suitable planting density of 26.88×104 hills ha–1 and may be an alternative approach to improving grain yield and quality for japonica rice.
    Improved soil characteristics in the deeper plough layer can increase grain yield of winter wheat
    CHEN Jin, PANG Dang-wei, JIN Min, LUO Yong-li, LI Hao-yu, LI Yong, WANG Zhen-lin
    2020, 19(5): 1215-1226.  DOI: 10.1016/S2095-3119(19)62679-1
    Abstract ( )   PDF in ScienceDirect  
    In the North China Plain (NCP), soil deterioration threatens winter wheat (Triticum aestivum L.) production.  Although rotary tillage or plowing tillage are two methods commonly used in this region, research characterizing the effects of mixed tillage on soil characteristics and wheat yield has been limited.  A fixed-site field trial was carried out during 2011–2016 to examine the impacts of three tillage practices (5-year rotary tillage with maize straw removal (RT); 5-year rotary tillage with maize straw return (RS); and annual RS and with a deep plowing interval of 2 years (RS/DS)) on soil characteristics and root distribution in the plough layer.  Straw return significantly decreased soil bulk density, increased soil organic carbon (SOC) storage and SOC content, macro-aggregate proportion (R0.25) and its stability in the plough layer.  The RS/DS treatment significantly increased the SOC content, total nitrogen (TN), and root length density (RLD) in the 10–40 cm layer, and enhanced the proportion of RLD in the 20–30 and 30–40 cm layers.  In the 20–30 and 30–40 cm layers, an increase in SOC and TN could lead to higher grain production than commensurate increases in the surface layer, resulting in a sustainable increase in grain yield from the RS/DS treatment.  Thus, the RS/DS treatment could lead to high productivity of winter wheat by improving soil characteristics and root distribution at the deeper plough layer in the NCP.
    Interacting leaf dynamics and environment to optimize maize sowing date in North China Plain
    TIAN Bei-jing, ZHU Jin-cheng, LIU Xi-wei, HUANG Shou-bing, WANG Pu
    2020, 19(5): 1227-1240.  DOI: 10.1016/S2095-3119(19)62831-5
    Abstract ( )   PDF in ScienceDirect  
    Leaf growth and its interaction with the growing environment critically affect leaf area, distribution, and function, and ultimately affects grain yield of maize (Zea mays L.).  To detect the effects of leaf area dynamics, growth periods, and the environment on maize grain yield, a three-year field experiment was conducted using two maize varieties, medium plant-size variety Zhengdan 958 (ZD958) and large plant-size variety Zhongnongda 4 (ZND4), and three to five sowing dates.  The sowing date significantly affected maize yield as a result of changes in leaf area, growth stage, and growing environment.  Prior to the 12th leaf stage, significant correlations between leaf area dynamics, environment, and yield were seldom detected.  The expansion of leaf area from 12th leaf stage to silking stage was significantly positively correlated with growing degree days (GDD), solar radiation, and grain yield, indicating the importance of leaf area dynamics during this period.  After silking, solar radiation played a more important role in inducing leaf senescence than GDD, particularly in the 2nd half of the grain filling stage.  Accelerated leaf senescence in late growth period can increase maize yield.  The environment affected leaf area dynamics and yield of the large plant-size variety (ZND4) more easily than the medium plant-size variety (ZD958) at the optimum plant density, reflecting the difference in varietal capacity to adapt to the growing environment.  This study indicates that optimizing the interaction among leaf area dynamics, growth periods, and environment is a sound strategy to increase maize yield.  Favorable interactions are useful to determine the optimal sowing date of a given variety.
    Optimizing agronomic practices for closing rapeseed yield gaps under intensive cropping systems in China
    ZHANG Zhi, CONG Ri-huan, REN Tao, LI Hui, ZHU Yun, LU Jian-wei
    2020, 19(5): 1241-1249.  DOI: 10.1016/S2095-3119(19)62748-6
    Abstract ( )   PDF in ScienceDirect  
    A yield gap analysis for rapeseed (Brassica napus L.) is critical to meeting the oil demand by identifying yield potential and yield constraints. In this study, potential yield (Yp), attainable yield (Yatt), and actual yield (Yact) for winter rapeseed were determined in five different zones of China.  A boundary line approach was adopted to calculate Yp, based on a large-scale field experimental database.  A meta-analysis was conducted on the data obtained from 118 published studies to evaluate the effects of agronomic factors on rapeseed yield.  The main results indicated that farmers only achieved 37–56% of the yield potential across the zones.  The low altitude areas (L-URY) and lower reaches (LRY) of the Yangtze River Basin (YRB), China had high yield levels.  The total yield gap was 1 893 kg ha–1, due to the agronomic management factors, environmental factors, and socioeconomic factors.  The meta-analysis showed that weed control and drainage were the best management practices to improve yields (45.6 and 35.3%, respectively), and other practices improved yields by 17.1–21.6%.  Consequently, to narrow the yield gap over the short term, the study could focus on techniques that are easily implemented to farmers.
    Genome-wide identification and expression analysis of anthocyanin biosynthetic genes in Brassica juncea
    ZHANG Da-wei, LIU Li-li, ZHOU Ding-gang, LIU Xian-jun, LIU Zhong-song, YAN Ming-li
    2020, 19(5): 1250-1260.  DOI: 10.1016/S2095-3119(20)63172-0
    Abstract ( )   PDF in ScienceDirect  
    Anthocyanins confer the wide range of colors for plants and also play beneficial health roles as potentially protective factors against heart disease and cancer.  Brassica juncea is cultivated as an edible oil resource and vegetable crop worldwide, thus elucidating the anthocyanin biosynthetic pathway would be helpful to improve the nutritional quality of Brassica juncea through the breeding and cultivating of high anthocyanin content varieties.  Herein, 129 genes in B. juncea were identified as orthologs of 41 anthocyanin biosynthetic genes (ABGs) in Arabidopsis thaliana by comparative genomic analyses.  The B. juncea ABGs have expanded by whole genome triplication and subsequent allopolyploidizatoin, but lost mainly during the whole genome triplication between B. rapa/B. nigra and A. thaliana, rather than the allopolyploidization process between B. juncea and B. rapa/B. nigra, leading to different copy numbers retention of A. thaliana homologous genes.  Although the overall expansion levels ABGs were similar to the whole genome, more negative regulatory genes were retained in the anthocyanin biosynthesis regulatory system.  Transcriptional analysis of B. juncea with different anthocyanin accumulation showed that BjDFR, BjTT19, BjTT8 are significantly up-regulated in plants with purple leaves as compared with green leaves.  The overexpression of BjTT8 and these target genes which were involved in late anthocyanin biosynthesis and transport might account for increasing levels of anthocyanin accumulation in purple leaves.  Our results could promote the understanding of the genetic mechanism of anthocyanin biosynthesis in B. juncea.
    Genome-wide identification and expression analysis of asparagine synthetase family in apple
    YUAN Xi-sen, YU Zi-peng, LIU Lin, XU Yang, ZHANG Lei, HAN De-guo, ZHANG Shi-zhong
    2020, 19(5): 1261-1273.  DOI: 10.1016/S2095-3119(20)63171-9
    Abstract ( )   PDF in ScienceDirect  
    Asparagine is an efficient nitrogen transport and storage carrier.  Asparagine synthesis occurs by the amination of aspartate which is catalyzed by asparagine synthetase (ASN) in plants.  Complete genome-wide analysis and classifications of the ASN gene family have recently been reported in different plants.  However, systematic analysis and expression profiles of these genes have not been performed in apple (Malus domestica).  Here, a comprehensive bioinformatics approach was applied to identify MdASNs in apple.  Then, plant phylogenetic tree, chromosome location, conserved protein motif, gene structure, and expression pattern of MdASNs were analyzed.  Five members were identified and distributed on 4 chromosomes with conserved GATase-7 and ASN domains.  Expression analysis indicated that all MdASNs mRNA accumulated at the highest level in reproductive organs, namely flowers or fruits, which may be associated with the redistribution of free amino acids in plant metabolic organs and reservoirs.  Additionally, most of MdASNs were dramatically up-regulated under various nitrogen supplies, especially in the aboveground part.  Taken together, MdASNs may be assigned to be responsible for the nitrogen metabolism and asparagine synthesis in apple.
    Plant Protection
    Rapid detection of potato late blight using a loop-mediated isothermal amplification assay
    KONG Liang, WANG Hui-bin, WANG Shuai-shuai, XU Ping-ping, ZHANG Ruo-fang, DONG Suo-meng, ZHENG Xiao-bo
    2020, 19(5): 1274-1282.  DOI: 10.1016/S2095-3119(19)62816-9
    Abstract ( )   PDF in ScienceDirect  
    Potato late blight caused by Phytophthora infestans is one of the most destructive plant diseases that threaten global food security.  Early and effective diagnosis of P. infestans is required before disease management decisions are made.  Here, we developed a quick protocol to detect P. infestans based on a loop-mediated isothermal amplification (LAMP) assay.  The P. infestans specific multiple copy DNA sequences (PiSMC), a transposon-like element, provides an ideal target for molecular detection of this pathogen.  We designed highly specific and sensitive primers allowing effective LAMP detection of the pathogen at 64°C in 70 min.  In the validation assay, all 15 P. infestans isolates collected from China, Europe and South America could be positively detected, but results of the other 9 Phytophthora species infecting different plants, fungal and bacterial plant pathogens tested were negative.  The detection limit of this assay is 1 pg P. infestans DNA.  Moreover, the LAMP-PiSMC assay is able to detect P. infestans from infected leaves, tubers and soil.  Taken together, this study reports the development of a specific and sensitive LAMP-PiSMC assay for early diagnosis of potato late blight.
    Monoclonal antibody-based serological detection of potato virus M in potato plants and tubers
    ZHANG Yu, GAO Yan-ling, HE Wan-qin, WANG Ya-qin, QIAN Ya-juan, ZHOU Xue-ping, WU Jian-xiang
    2020, 19(5): 1283-1291.  DOI: 10.1016/S2095-3119(19)62755-3
    Abstract ( )   PDF in ScienceDirect  
    Potato virus M (PVM) is one of the common and economically important potato viruses in potato-growing regions worldwide.  To investigate and control this viral disease, efficient and specific detection techniques are needed.  In this study, PVM virions were purified from infected potato plants and used as the immunogen to produce hybridomas secreting PVM-specific monoclonal antibodies (MAbs).  Four highly specific and sensitive murine MAbs, i.e., 1E1, 2A5, 8A1 and 17G8 were prepared through a conventional hybridoma technology.  Using these four MAbs, we have developed an antigen-coated plate (ACP)-ELISA, a dot-ELISA and a Tissue print-ELISA for detecting PVM infection in potato plants and tubers.  PVM could be detected in infected potato plant tissue crude extracts diluted at 1:10 240 (w/v, g mL–1) by the dot-ELISA or at 1:163 840 (w/v, g mL–1) by the ACP-ELISA.  The Tissue print-ELISA is the quickest and easiest assay among the three established serological assays and is more suitable for onsite large-scale sample detection.  Detection results of the field-collected samples showed that PVM is currently widespread in the Yunnan and the Heilongjiang provinces in China.  The field sample test results of the developed serological assays were supported by the results from RT-PCR and DNA sequencing.  We consider that the newly established ACP-ELISA, dot-ELISA and Tissue print-ELISA can benefit PVM detection in potato plant and tuber samples and field epidemiological studies of PVM.  These assays can also facilitate the production of virus-free seed potatoes and breeding for PVM-resistant potato cultivars, leading to the successful prevention of this potato viral disease.
    MmNet: Identifying Mikania micrantha Kunth in the wild via a deep Convolutional Neural Network
    QIAO Xi, LI Yan-zhou, SU Guang-yuan, TIAN Hong-kun, ZHANG Shuo, SUN Zhong-yu, YANG Long, WAN Fang-hao, QIAN Wan-qiang
    2020, 19(5): 1292-1300.  DOI: 10.1016/S2095-3119(19)62829-7
    Abstract ( )   PDF in ScienceDirect  
    Mikania micrantha Kunth is an invasive alien weed and known as a plant killer around the world.  Accurately and rapidly identifying M. micrantha in the wild is important for monitoring its growth status, as this helps management officials to take the necessary steps to devise a comprehensive strategy to control the invasive weed in the identified area.  However, this approach still mainly depends on satellite remote sensing and manual inspection.  The cost is high and the accuracy rate and efficiency are low.  We acquired color images of the monitoring area in the wild environment using an Unmanned Aerial Vehicle (UAV) and proposed a novel network -MmNet- based on a deep Convolutional Neural Network (CNN) to identify M. micrantha in the images.  The network consists of AlexNet Local Response Normalization (LRN), along with the GoogLeNet and continuous convolution of VGG inception models.  After training and testing, the identification of 400 testing samples by MmNet is very good, with accuracy of 94.50% and time cost of 10.369 s.  Moreover, in quantitative comparative analysis, the proposed MmNet not only has high accuracy and efficiency but also simple construction and outstanding repeatability.  Compared with recently popular CNNs, MmNet is more suitable for the identification of M. micrantha in the wild.  However, to meet the challenge of wild environments, more M. micrantha images need to be acquired for MmNet training.  In addition, the classification labels need to be sorted in more detail.  Altogether, this research provides some theoretical and scientific basis for the development of intelligent monitoring and early warning systems for M. micrantha and other invasive species. 
    Using an image segmentation and support vector machine method for identifying two locust species and instars
    Shuhan LU, YE Si-jing
    2020, 19(5): 1301-1313.  DOI: 10.1016/S2095-3119(19)62865-0
    Abstract ( )   PDF in ScienceDirect  
    Locusts are agricultural pests around the world.  To cognize how locust distribution density and community structure are related to the hydrothermal and vegetation growth conditions of their habitats and thereby providing rapid and accurate warning of locust invasions, it is important to develop efficient and accurate techniques for acquiring locust information.  In this paper, by analyzing the differences between the morphological features of Locusta migratoria manilensis and Oedaleus decorus asiaticus, we proposed a semi-automatic locust species and instar information detection model based on locust image segmentation, locust feature variable extraction and support vector machine (SVM) classification.  And we subsequently examined its applicability and accuracy based on sample image data acquired in the field.  Locust image segmentation experiment showed that the proposed GrabCut-based interactive segmentation method can be used to rapidly extract images of various locust body parts and exhibits excellent operability.  In a locust feature variable extraction experiment, the textural, color and morphological features of various locust body parts were calculated.  Based on the results, eight feature variables were selected to identify locust species and instars using outlier detection, variable function calculation and principal component analysis.  An SVM-based locust classification experiment achieved a semi-automatic detection accuracy of 96.16% when a polynomial kernel function with a penalty factor parameter c of 2 040 and a gamma parameter g of 0.5 was used.  The proposed detection model exhibits advantages such as high applicability and accuracy when it is used to identify locust instars of L. migratoria manilensis and O. decorus asiaticus, and it can also be used to identify other species of locusts.
    Animal Science · Veterinary Medicine
    Genome-wide detection of selective signatures in a Jinhua pig population
    XU Zhong, SUN Hao, ZHANG Zhe, Zhao Qing-bo, Babatunde Shittu Olasege, Li Qiu-meng, Yue Yang, Ma Pei-pei, Zhang Xiang-zhe, Wang Qi-shan, Pan Yu-chun
    2020, 19(5): 1314-1322.  DOI: 10.1016/S2095-3119(19)62833-9
    Abstract ( )   PDF in ScienceDirect  
    The aim of this study was to detect evidence for signatures of recent selection in the Jinhua pig genome.  These results can be useful to better understand the regions under selection in Jinhua pigs and might shed some lights on groups of genes that control production traits.  In the present study, we performed extended haplotype homozygosity (EHH) tests to identify significant core regions in 202 Jinhua pigs.  A total of 26 161 core regions spanning 636.42 Mb were identified, which occupied approximately 28% of the genome across all autosomes, and 1 158 significant (P<0.01) core haplotypes were selected.  Genes in these regions were related to several economically important traits, including meat quality, reproduction, immune responses and exterior traits.  A panel of genes including ssc-mir-365-2, KDM8, RABEP2, GSG1L, RHEB, RPH3AL and a signal pathway of PI3K-Akt were detected with the most extreme P-values.  The findings in our study could draw a comparatively genome-wide map of selection signature in the pig genome, and also help to detect functional candidate genes under positive selection for further genetic and breeding research in Jinhua and other pigs.
    Effect of transferring lignocellulose-degrading bacteria from termite to rumen fluid of sheep on in vitro gas production, fermentation parameters, microbial populations and enzyme activity
    Ayoub AZIZI, Afrooz SHARIFI, Hasan FAZAELI, Arash AZARFAR, Arjan JONKER, Ali KIANI
    2020, 19(5): 1323-1331.  DOI: 10.1016/S2095-3119(19)62854-6
    Abstract ( )   PDF in ScienceDirect  
    The digestive tract of termite (Microcerotermes diversus) contains a variety of lignocellulose-degrading bacteria with exocellulases enzyme activity, not found in the rumen, which could potentially improve fiber degradation in the rumen.  The objectives of the current study were to determine the effect of inoculation of rumen fluid (RF) with three species of bacteria isolated from termite digestive tract, Bacillus licheniformis, Ochrobactrum intermedium, and Microbacterium paludicola, on in vitro gas production (IVGP), fermentation parameters, nutrient disappearance, microbial populations, and hydrolytic enzyme activities with fibrous wheat straw (WS) and date leaf (DL) as incubation substrate.  Inoculation of RF with either of three termite bacteria increased (P<0.05) ammonia-N concentration compared with the control group (free of termite gut bacteria).  Termite bacteria inoculation had no effect (P>0.05) on gas production characteristics, dry matter, organic matter and neutral detergent fiber disappearance, pH, and concentration and composition of volatile fatty acids.  Population of proteolytic bacteria and protozoa, but not cellulolytic bacteria, were increased (P<0.05) when RF was inoculated with termite bacteria with both WS and DL substrates.  Inoculation of RF with termite bacteria increased protease activity, while activities of carboxymethyl-cellulase, microcrystalline-cellulase, α-amylase and filter paper degrading activity remained unchanged (P>0.05).  Overall, the results of this study indicated that transferring lignocellulose-degrading bacteria, isolated from digestive tract of termite, to rumen liquid increased protozoa and proteolytic bacteria population and consequently increased protease activity and ammonia-N concentration in vitro, however, no effect on fermentation and fiber degradation parameters were detected.  These results suggest that the termite bacteria might be rapidly lysed by the rumen microbes before beneficial effects on the rumen fermentation process could occur.
    Lactate dehydrogenase: An important molecule involved in acetamizuril action against Eimeria tenella
    LIU Li-li, FEI Chen-zhong, DONG Hui, ZHANG Ke-yu, Fu Jian-jun, LI Tao, XUE Fei-qun
    2020, 19(5): 1332-1339.  DOI: 10.1016/S2095-3119(19)62845-5
    Abstract ( )   PDF in ScienceDirect  
    Lactate dehydrogenase (LDH), a vital enzyme in anaerobic glycolysis, is closely associated with the survival of parasites.  Previous studies of some parasites have shown that LDH exhibits unique physicochemical properties and molecular structures and may be an ideal potential target for diagnosis and drug screening.  In this study, we aimed to investigate the effects of acetamizuril, a novel anticoccidial compound, on LDH in the second-generation merozoites of Eimeria tenella (mz-LDH).  Quantitative real-time PCR, Western blot, immunofluorescence and enzyme activity assays were each applied to detect the changes of mz-LDH.  Our results indicated that the mRNA and protein levels of mz-LDH were reduced upon acetamizuril treatment.  Immunolocalization of mz-LDH demonstrated that considerable amount of mz-LDH was distributed around or in the nuclei of second-generation merozoites within the untreated group; in contrast, the acetamizuril-treated group had very low level of mz-LDH.  Meanwhile, LDH enzyme activity assay suggested that a decreased LDH enzyme activity in both cytoplasm and nucleus of merozoites in the acetamizuril-treated group.  Moreover, the induced apoptosis in second-generation merozoites by the acetamizuril was evaluated by detecting caspase 3 activity, and acetamizuril was found to significantly increase caspase 3 activity.  The above findings show that LDH may play an important role in the mediating the activity of acetamizuril against coccidiosis, and further investigation into this aspect might contribute to new light on the pathogenesis of E. tenella during its interaction with acetamizuril.
    Agro-ecosystem & Environment
    Strategies for timing nitrogen fertilization of pear trees based on the distribution, storage, and remobilization of 15N from seasonal application of (15N H4)2SO4
    JIANG Hai-bo, LI Hong-xu, ZHAO Ming-xin, MEI Xin-lan, KANG Ya-long, DONG Cai-xia, XU Yang-chun
    2020, 19(5): 1340-1353.  DOI: 10.1016/S2095-3119(19)62758-9
    Abstract ( )   PDF in ScienceDirect  
    In order to improve the management of nitrogen (N) fertilization in pear orchards, we investigated the effects of application timing on the distribution, storage, and remobilization of N in mature pear trees in a field experiment at Jingtai County, Gansu Province, China.  Nine trees were selected for the experiment and each received equal aliquots of 83.33 g N in the autumn, spring, and summer, with 15N-labeled (NH4)2SO4 used in one of the aliquots each season.  Results showed that the (15NH4)2SO4 applied in the autumn remained in the soil during the winter.  In the following spring this N was absorbed and rapidly remobilized into each organ, especially new organs (leaves, fruit and new shoots).  The 15N supplied in spring was rapidly transported to developing fruit between the young fruit and fruit enlargement stages.  15N from the summer application of fertilizer was mainly stored in the coarse roots over the winter, then was mobilized to support growth of new organs in spring.  In conclusion, for pear trees we recommend that the autumn application of N-fertilizer be soon after fruit harvest in order to increase N stores in fine roots.  Spring application should be between full bloom and the young fruit stages to meet the high N demands of developing fruit.  Summer application of fertilizer at the fruit enlargement stage does not contemporaneously affect the growth of pears, but increases the N stored in coarse roots, and in turn the amount available for remobilization in spring.
    Long-term fertilization leads to specific PLFA finger-prints in Chinese Hapludults soil
    WANG Qi-qi, LIU Ling-ling, LI Yu, QIN Song, WANG Chuan-jie, CAI An-dong, WU Lei, XU Ming-gang, ZHANG Wen-ju
    2020, 19(5): 1354-1362.  DOI: 10.1016/S2095-3119(19)62866-2
    Abstract ( )   PDF in ScienceDirect  
    Soil microbes play essential roles in the biogeochemical processes of organic carbon and nutrient cycling.  Many studies have reported various short-term effects of fertilization on soil microbes.  However, less is known about the effects of long-term fertilization regimes on the rhizosphere.  Therefore, the objective of this study was to explore how the soil microbial communities in the rhizosphere respond to different long-term fertilization strategies.  Based on a 21-year field treatment experiment in Guizhou, China, we extracted phospholipid fatty acids (PLFAs) to determine the microbial community structure in both the non-rhizosphere (NR) and rhizosphere (R).  Six treatments were included: no fertilizer (CK), mineral nitrogen fertilizer (N), N with potassium (NK), phosphorus with K (PK), NPK, and NPK combined with manure (MNPK).  The results showed that total PLFAs under unbalanced mineral fertilization (N, NK and PK) were decreased by 45% on average in the NR compared with CK, whereas MNPK increased fungi and G–bacteria abundance significantly in both the NR (by 33 and 23%) and R (by 15 and 20%), respectively.  In addition, all microbial groups in the R under these treatments (N, NK and PK) were significantly increased relative to those in the NR, except for the ratio of F/B and G+/G–, which might be due to the high nutrient availability in the R.  Soil pH and SOC significantly regulated the soil microbial community and structure, explaining 51 and 20% of the variation in the NR, respectively.  However, the rhizosphere microbial community structure was only significantly affected by soil pH (31%).  We concluded that the soil microbial community in the NR was more strongly affected by long-term fertilization than that in the R due to the rhizosphere effect in the agricultural ecosystem.  Rhizosphere nutrient conditions and buffering capacity could help microbial communities resist the change from the long-term fertilization.
    The effects of water and nitrogen on the roots and yield of upland and paddy rice
    ZHANG Ya-jie, XU Jing-nan, CHENG Ya-dan, WANG Chen, LIU Gao-sheng, YANG Jian-chang
    2020, 19(5): 1363-1374.  DOI: 10.1016/S2095-3119(19)62811-X
    Abstract ( )   PDF in ScienceDirect  
    It is of great significance to study the root characteristics of rice to improve water and nitrogen (N) use efficiency and reduce environmental pollution.  This study investigated whether root traits and architecture of rice influence grain yield, as well as water and N utilization efficiency.  An experiment was conducted using the upland rice cultivar Zhonghan 3 (a japonica cultivar) and paddy rice cultivar Huaidao 5 (also a japonica cultivar) using three N levels, namely, 2 g urea/pot (low amount, LN), 3 g urea/pot (normal amount, NN), and 4 g urea/pot (high amount, HN), and three soil water potentials (SWPs, namely, well-watered (0 kPa), mildly dried (–20 kPa) and severely dried (–40 kPa).  The results showed that with decreasing SWP, the percentage of upland rice roots increased in the 0–5 cm tillage layer, and decreased in the 5–10 and 10–20 cm tillage layers, whereas paddy rice roots showed the opposite trend.  With increasing amounts of N, the yield of upland and paddy rice increased, and the percentage of root volume ratios of the two rice cultivars in the 0–5 and 5–10 cm tillage layers increased, whereas that in the 10–20 cm tillage layer decreased.  The roots of upland rice are mainly distributed in the 10–20 cm tillage layer, whereas most paddy rice roots are in the 0–5 cm tillage layer.  These results indicate that the combination of −20 kPa SWP and NN in upland rice and 0 kPa SWP and LN in paddy rice promotes the growth of the root system during the middle and late stages, which in turn may decrease the requirements for water and N fertilizer and increase rice yield. 
    The effects of calcium combined with chitosan amendment on the bioavailability of exogenous Pb in calcareous soil
    CHANG Hui-qing, WANG Qi-zhen, LI Zhao-jun, WU Jie, XU Xiao-feng, SHI Zhao-yong
    2020, 19(5): 1375-1386.  DOI: 10.1016/S2095-3119(19)62861-3
    Abstract ( )   PDF in ScienceDirect  
    Lead (Pb) in soil may accumulate in crops and enter the human body.  This study aimed to understand the speciation transformation and accumulation characteristics of exogenous Pb in calcareous soil with or without the application of soil amendments.  Field experiments with continuous maize cultivation have been carried out for two years.  The results showed that the contents of total Pb were slightly lower in 2016 than in 2015 for the same treatments; however, no significant difference between the years was observed.  Soil Pb existed mainly in the residual fraction without exogenous Pb addition, and its proportion was more than 33% of the total soil Pb in the control and Ca treatments.  When Pb was added to calcareous soil, Pb existed largely in the oxidizable and reducible fractions during the two-year experimental period, and those fractions made up over 83% of the total Pb.  The proportion of the water-soluble Pb, regardless of the addition of Pb, was the lowest and was less than 0.0019% in all treatments, but the addition of Ca and chitosan amendments reduced the water-soluble and exchangeable Pb contents.  The Pb content in different parts of maize followed the order root>leaf>stem>grain during the experimental period.  Although maize had low transfer and enrichment factors in calcareous soil, which make the Pb content in the grain show no significant difference among the five treatments in the same year, adding Ca and chitosan to calcareous soil can reduce the Pb contents of maize, especially reduce the Pb contents of root, stem and leaf.  Therefore, the addition of calcium and chitosan is an effective strategy for reducing Pb availability in calcareous soils.
    Food Science
    Effects of UV-B treatment on controlling lignification and quality of bamboo (Phyllostachys prominens) shoots without sheaths during cold storage
    ZHENG Jian, LI Sheng-e, Maratab ALI, HUANG Qi-hui, ZHNEG Xiao-lin, PANG Lin-jiang
    2020, 19(5): 1387-1395.  DOI: 10.1016/S2095-3119(20)63170-7
    Abstract ( )   PDF in ScienceDirect  
    For evaluating the effects of UV-B treatment on lignification and quality of bamboo (Phyllostachys prominens) shoots during postharvest, fresh bamboo shoots without sheaths were irradiated with UV-B at a dose of 8.0 kJ m–2 and then stored at (6±1)°C along with 85–90% relative humidity (RH) for 15 d.  The results showed that UV-B treatment apparently slowed down the increase rates of flesh firmness, weight loss, and contents of cellulose and lignin.  It also decreased the activities of 4-coumarate CoA ligase (4CL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and phenylalanine ammonia-lyase (PAL) and the expression of their encoding genes during cold storage.  It was suggested that these effects of UV-B treatment on decreases in these enzymatic activities and the expression of encoding genes might collectively regulate lignin synthesis and accumulation in the flesh of bamboo shoots and consequently benefit in maintaining the edible quality of bamboo shoots during cold storage.
    Effects of INA on postharvest blue and green molds and anthracnose decay in citrus fruit
    JING Jia-yi, ZHANG Hong-yan, XUE Yao-bi, ZENG Kai-fang
    2020, 19(5): 1396-1406.  DOI: 10.1016/S2095-3119(20)63169-0
    Abstract ( )   PDF in ScienceDirect  
    As a synthetic functional analog of salicylic acid, 2,6-dichloroisonicotinic acid (INA) is effective in inducing the host disease resistance of a plant against a pathogen.  The effects of INA on controlling postharvest blue and green molds and anthracnose decay and defense-related enzymes on citrus fruits were investigated, and the ascorbic acid of naturally infected citrus flavedo was also measured.  Results showed that 1.0 mmol L–1 INA treatments significantly reduced blue and green molds and anthracnose decay development on both wound-inoculated fruit and naturally-infected fruit compared with the control fruit.  The treatment effectively enhanced the β-1,3-glucanase (GLU), chitinase (CHI), phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities and the polyphenol oxidase (PPO) in flavedo.  The results presented here suggest that INA might be used as a chemical fungicide substitution to control postharvest diseases in citrus fruits.
    QTL-allele matrix detected from RTM-GWAS is a powerful tool for studies in genetics, evolution, and breeding by design of crops
    HE Jian-bo, GAI Jun-yi
    2020, 19(5): 1407-1410.  DOI: 10.1016/S2095-3119(20)63199-9
    Abstract ( )