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Frontiers of Agricultural Science and Engineering

  • Cover Illustration

    2019, Vol.6  No.2

    Plant nucleotide-binding and leucine-rich repeat (NLR) receptors recognize pathogens and mediate innate immune responses that usually associate with hypersensitive cell death. We summarized the recent advances on the regulation of NLR stability in plant immunity. This picture depicts the major pathways/components in the stability regulation of NLRs in plants.
    (Tao WANG, Jiaxin LI, Qian-Hua SHEN, pp. 97-104)

    Table of Contents

ISSN 2095-7505 (Print)
ISSN 2095-977X (Online)
CN 10-1204/S
Postal Subscription Code 80-906

Frontiers of Agricultural Science and Engineering has been added to Directory of Open Access Journals (DOAJ) on September 12, 2016.

This journal is a member of, and subscribes to the principles of, the Committee on Publication Ethics (COPE)

, Volume 6 Issue 2

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REVIEW
Regulation of NLR stability in plant immunity
Tao WANG, Jiaxin LI, Qian-Hua SHEN
Front. Agr. Sci. Eng. . 2019, 6 (2): 97-104.  https://doi.org/10.15302/J-FASE-2018248
Abstract   HTML   PDF (516KB)

Plant nucleotide binding domain and leucine-rich repeat (NLR) receptors recognize pathogen effectors directly or indirectly and mediate innate immune responses. NLR-mediated immunity also has direct impacts on plant growth and development, as well as yield and survival. The levels of NLR proteins are therefore intricately controlled in plants to balance defense responses and other processes. In recent years, the ubiquitination-26S proteasome system and the HSP90 chaperones have emerged as having key functions in the regulation of NLR stability. The N-end rule pathway of protein degradation is also directly linked to NLR stability. Recent progress in the regulation of NLR stability and turnover is summarized here, focusing on the key components and pathways.

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Factors influencing near infrared spectroscopy analysis of agro-products: a review
Xiao XU, Lijuan XIE, Yibin YING
Front. Agr. Sci. Eng. . 2019, 6 (2): 105-115.  https://doi.org/10.15302/J-FASE-2019255
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The near infrared (NIR) spectroscopy technique has wide applications in agriculture with the advantages of being nondestructive, sensitive, safe and rapid. However, there are still more than 40 error sources influencing the robustness and accuracy of its calibration and operation. Environmental, sample and instrument factors that influence the analysis are discussed in this review, including temperature, humidity and other factors that introduce uncertainty. Error sources from livestock products, fruit and vegetables, which are the most common objects in the field of NIR analysis, are also emphasized in the second part. In addition, studies utilizing different instruments, spectral pretreatments, variable selection methods, wavelength ranges, detection modes and calibration methods are tabulated to illustrate the complications they introduce and how they influence NIR analysis. It is suggested that large scale of data with abundant varieties can be used to build a more robust calibration model, in order to improve the robustness and accuracy of the NIR analytical model, and overcome problems caused by confining analysis to too many uniform samples.

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A comparative review of the state and advancement of Site-Specific Crop Management in the UK and China
Zhenhong LI, James TAYLOR, Lynn FREWER, Chunjiang ZHAO, Guijun YANG, Zhenhai LI, Zhigang LIU, Rachel GAULTON, Daniel WICKS, Hugh MORTIMER, Xiao CHENG, Chaoqing YU, Zhanyi SUN
Front. Agr. Sci. Eng. . 2019, 6 (2): 116-136.  https://doi.org/10.15302/J-FASE-2018240
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Precision agriculture, and more specifically Site-Specific Crop Management (SSCM), has been implemented in some form across nearly all agricultural production systems over the past 25 years. Adoption has been greatest in developed agricultural countries. In this review article, the current situation of SSCM adoption and application is investigated from the perspective of a developed (UK) and developing (China) agricultural economy. The current state-of-the art is reviewed with an emphasis on developments in position system technology and satellite-based remote sensing. This is augmented with observations on the differences between the use of SSCM technologies and methodologies in the UK and China and discussion of the opportunities for (and limitations to) increasing SSCM adoption in developing agricultural economies. A particular emphasis is given to the role of socio-demographic factors and the application of responsible research and innovation (RRI) in translating agri-technologies into China and other developing agricultural economies. Several key research and development areas are identified that need to be addressed to facilitate the delivery of SSCM as a holistic service into areas with low precision agriculture (PA) adoption. This has implications for developed as well as developing agricultural economies.

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RESEARCH ARTICLE
Polyaniline–polypyrrole nanocomposites using a green and porous wood as support for supercapacitors
Jian LI, Yue JIAO
Front. Agr. Sci. Eng. . 2019, 6 (2): 137-143.  https://doi.org/10.15302/J-FASE-2019257
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Wood is an ideal type of support material whose porous structure and surface functional groups are beneficial for deposition of various guest substances for different applications. In this paper, wood is employed as a porous support, combined with two kinds of conductive polymers (i.e., polyaniline (PANI) and polypyrrole (PPy)) using an easy and fast liquid polymerization method. Scanning electron microscope observations indicate that the PANI–PPy complex consists of nanoparticles with a size of ~20 nm. The interactions between oxygen-containing groups of the wood and the nitrogen composition of PANI–PPy were verified by Fourier transform infrared spectroscopy. The self-supported PANI–PPy/wood composite is capable of acting as a free-standing supercapacitor electrode, which delivers a high gravimetric specific capacitance of 360 F·g1 at 0.2 A·g1.

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Modeling water and heat transfer in soil-plant-atmosphere continuum applied to maize growth under plastic film mulching
Meng DUAN, Jin XIE, Xiaomin MAO
Front. Agr. Sci. Eng. . 2019, 6 (2): 144-161.  https://doi.org/10.15302/J-FASE-2019258
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Based on our previous work modeling crop growth (CropSPAC) and water and heat transfer in the soil-plant-atmosphere continuum (SPAC), the model was improved by considering the effect of plastic film mulching applied to field-grown maize in North-west China. In CropSPAC, a single layer canopy model and a multi-layer soil model were adopted to simulate the energy partition between the canopy and water and heat transfer in the soil, respectively. The maize growth module included photosynthesis, growth stage calculation, biomass accumulation, and participation. The CropSPAC model coupled the maize growth module and SPAC water and heat transfer module through leaf area index (LAI), plant height and soil moisture condition in the root zone. The LAI and plant height were calculated from the maize growth module and used as input for the SPAC water and heat transfer module, and the SPAC module output for soil water stress conditions used as an input for maize growth module. We used rs, the representation of evaporation resistance, instead of the commonly used evaporation resistance rs0 to reflect the change of latent heat flux of soil evaporation under film mulching as well as the induced change in energy partition. The model was tested in a maize field at Yingke irrigation area in North-west China. Results showed reasonable agreement between the simulations and measurements of LAI, above-ground biomass and soil water content. Compared with the original model, the modified model was more reliable for maize growth simulation under film mulching and showed better accuracy for the LAI (with the coefficient of determination R2 = 0.92, the root mean square of error RMSE= 1.23, and the Nush-Suttclife efficiency Ens = 0.87), the above-ground biomass (with R2 = 0.96, RMSE= 7.17 t·ha1 and Ens = 0.95) and the soil water content in 0–1 m soil layer (with R2 = 0.78, RMSE= 49.44 mm and Ens = 0.26). Scenarios were considered to simulate the influence of future climate change and film mulching on crop growth, soil water and heat conditions, and crop yield. The simulations indicated that the change of LAI, leaf biomass and yield are negatively correlated with temperature change, but the growing degree-days, evaporation, soil water content and soil temperature are positively correlated with temperature change. With an increase in the ratio of film mulching area, the evaporation will decrease, while the impact of film mulching on crop transpiration is not significant. In general, film mulching is effective in saving water, preserving soil moisture, increasing soil surface temperature, shortening the potential growth period, and increasing the potential yield of maize.

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The diazotrophic community in oat rhizosphere: effects of legume intercropping and crop growth stage
Yadong YANG, Xiaomin FENG, Yuegao HU, Zhaohai ZENG
Front. Agr. Sci. Eng. . 2019, 6 (2): 162-171.  https://doi.org/10.15302/J-FASE-2018212
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In this study, the abundance, diversity and structure of the diazotrophic community in oat rhizosphere soil in three cropping systems and at two oat growth stages were investigated using real-time PCR and Illumina MiSeq sequencing. The nifH gene abundance in oat-soybean intercropping (OSO) and oat-mungbean intercropping (OMO) was significantly greater than that in sole oat (O), but the nifH gene abundance significantly decreased at the later stage in all the treatments. Alpha diversity indices in OSO and OMO were higher at the heading stage, but lower at the maturity stage than that in O. Bradyrhizobium and Skermanella were the dominant genera identified in all samples, with an average proportion of 35.8% and 12.4%, respectively. The proportion of dominant genera showed significant differences and varied with cropping system and growth stage. Principal component analysis showed that growth stage had a stronger effect than intercropping on the diazotrophic community structure. However, Mantel test and redundancy analysis showed there was no environmental factor significantly correlated to the diazotrophic community structure. Our results demonstrate that intercropping had a weaker effect than growth stage on the abundance, diversity and structure of the diazotrophic community in oat rhizosphere soil.

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Detection of Huanglongbing (citrus greening) based on hyperspectral image analysis and PCR
Kejian WANG, Dongmei GUO, Yao ZHANG, Lie DENG, Rangjin XIE, Qiang LV, Shilai YI, Yongqiang ZHENG, Yanyan MA, Shaolan HE
Front. Agr. Sci. Eng. . 2019, 6 (2): 172-180.  https://doi.org/10.15302/J-FASE-2019256
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Huanglongbing (HLB, citrus greening) is one of the most serious quarantine diseases of citrus worldwide. To monitor in real-time, recognize diseased trees, and efficiently prevent and control HLB disease in citrus, it is necessary to develop a rapid diagnostic method to detect HLB infected plants without symptoms. This study used Newhall navel orange plants as the research subject, and collected normal color leaf samples and chlorotic leaf samples from a healthy orchard and an HLB-infected orchard, respectively. First, hyperspectral data of the upper and lower leaf surfaces were obtained, and then the polymerase chain reaction (PCR) was used to detect the HLB bacterium in each leaf. The PCR test results showed that all samples from the healthy orchard were negative, and a portion of the samples from the infected orchard were positive. According to these results, the leaf samples from the orchards were divided into disease-free leaves and HLB-positive leaves, and the least squares support vector machine recognition model was established based on the leaf hyperspectral reflectance. The effect on the model of the spectra obtained from the upper and lower leaf surfaces was investigated and different pretreatment methods were compared and analyzed. It was observed that the HLB recognition rate values of the calibration and validation sets based on upper leaf surface spectra under 9-point smoothing pretreatment were 100% and 92.5%, respectively. The recognition rate values based on lower leaf surface spectra under the second-order derivative pretreatment were also 100% and 92.5%, respectively. Both upper and lower leaf surface spectra were available for recognition of HLB-infected leaves, and the HLB PCR-positive leaves could be distinguished from the healthy by the hyperspectral modeling analysis. The results of this study show that early and nondestructive detection of HLB-infected leaves without symptoms is possible, which provides a basis for the hyperspectral diagnosis of citrus with HLB.

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Evaluation of automated in-line precision dairy farming technology implementation in three dairy farms in Italy
Maria CARIA, Giuseppe TODDE, Antonio PAZZONA
Front. Agr. Sci. Eng. . 2019, 6 (2): 181-187.  https://doi.org/10.15302/J-FASE-2019252
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In recent decades, dairy farms have been exposed to wide variation in profit levels due to a considerable variability of milk price, and energy and feed costs. Consequently, it is necessary for the dairy industry to improve efficiency and productivity by adopting innovative technologies. The automated in-parlour milk analysis and separation is mainly useful to produce low or high quality milk and to monitor the animal health status. Milk with high levels of protein and fat contents may reduce the intensity of standardization during cheesemaking process, reducing production costs. The study aimed to evaluate the efficiency of real-time milk separation during milking and the performance of the milking machine after implementation of AfiMilk MCS. In addition, the economic aspects were assessed. The separation of milk required the existing milking parlors to be equipped with an additional milkline to allow channeling milk with low and high coagulation properties into two different cooling tanks. The results showed that the high coagulation milk fraction, compared to the bulk milk, increased in fat (from 18% to 43%) and protein (from 3% to 7%) concentration. The technology tested has given promising results showing reliability and efficiency in milk separation in real time with affordable implementation costs.

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Protective efficacy of vaccination with NcMIC3 and NcMIC8 against Neospora caninum infection in mice
Taotao ZHANG, Xiao ZHANG, Qun LIU, Jianhai XU, Jing LIU
Front. Agr. Sci. Eng. . 2019, 6 (2): 188-196.  https://doi.org/10.15302/J-FASE-2019253
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Microneme proteins (MICs) are important for Apicomplexan parasite invasion due to their adhesion to host cells. Several studies have indicated that Neospora caninum MIC3 and MIC8 are important adhesion factors and potential vaccine candidates against neosporosis. In this study, we evaluated the protective efficacy of recombinant proteins and DNA vaccines of NcMIC3 and NcMIC8. BALB/c mice were immunized with rNcMIC3, rNcMIC8, pcDNA3.1-NcMIC3 and pcDNA3.1-NcMIC8 respectively, and challenged with N. caninum tachyzoites. The immune responses were evaluated through cytokine, antibody measurements and the parasite burden in the mice brain tissues. Serological analysis showed that recombinant protein vaccines induced higher levels of immunoglobulin G (IgG) than other groups. The percentage of IgG1 and IgG2a in the recombinant protein groups was higher than the other groups, and with a predominance of IgG1 over IgG2a, suggesting that recombinant protein vaccines elicited a Th2-type immune response, while DNA vaccines mainly produce a Th1-type immune response. In addition, mice immunized with rNcMIC3 and rNcMIC8 a had lower parasite burden in brain tissue compared with the other groups. These results demonstrate that rNcMIC3 and rNcMIC8 could induce humoral and Th2-type immune response, leading to a considerable level of resistance against neosporosis.

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Leonurine protects ischemia-induced brain injury via modulating SOD, MDA and GABA levels
Shilei ZHENG, Jingru ZHU, Jiao LI, Shuang ZHANG, Yunfei MA
Front. Agr. Sci. Eng. . 2019, 6 (2): 197-205.  https://doi.org/10.15302/J-FASE-2018245
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The present study was designed to investigate the protective effects of leonurine, a compound purified from Herba Leonuri that is active on ischemic rat behavior and cortical neurons, and explore the underlying mechanism. The general rat activity, cortical neuron morphology, superoxide dismutase (SOD), malondialdehyde (MDA), g-aminobutyric acid (GABA) and glutamate decarboxylase 67 (GAD67) levels were measured. We found leonurine significantly improve the general activity of rats in an open-field test, which was associated with attenuated neuronal damage induced by ischemia. Moreover, serum SOD activity was significantly greater, MDA level lower in the leonurine group as compared with ischemia group. In addition, GABA content in the cerebral cortex was significantly greater in high-dose leonurine group. Correspondingly, GAD67 protein level coincided with the GABA level. Taken together, our results demonstrated that leonurine attenuated brain injury during ischemia via antioxidative and anti-excitotoxicity effects by targeting GABA and leonurine might become a useful adjuvant neuroprotective agent.

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ERRATUM
Coupling of the chemical niche and microbiome in the rhizosphere: implications from watermelon grafting
Yang SONG, Chen ZHU, Waseem RAZA, Dongsheng WANG, Qiwei HUANG, Shiwei GUO, Ning LING, Qirong SHEN
Front. Agr. Sci. Eng. . 2019, 6 (2): 206-206.  https://doi.org/10.15302/J-FASE-2018234
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