2020 Vol. 19 No. 3 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Animal Science · Veterinary Medicine
    Agro-ecosystem & Environment
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    Environmental risk for application of ammonia-soda white mud in soils in China
    WANG Xiao-bin, YAN Xiang, LI Xiu-ying
    2020, 19(3): 601-611.  DOI: 10.1016/S2095-3119(19)62745-0
    Abstract ( )   PDF in ScienceDirect  
    In recent years, some reports, mainly from Chinese research, show that there has been an increasing trend in the use of ammonia-soda residue (ASR) (or called ammonia-soda white mud) as a soil conditioner in farmlands.  Up to now, the studies on ASR have focused on its utilization for acid soil amendment in agriculture, but few studies have assessed its environmental risk.  ASR contains pollutant elements such as mercury (Hg), cadmium (Cd), copper (Cu) and fluorine (F) and the purpose of this study was to review research on the environmental impacts of ASR application in agriculture.  Observations obtained from 23 research reports indicate that the concentrations of  Hg, Cd, Cu, F and Cl (0–170, 0.01–2.8, 4.5–200, 2000–24700 and 1 600–188 000 mg kg–1, respectively) in ASR may exceed the limits (≤0.5, ≤0.3 and ≤50 mg kg–1 for Hg, Cd and Cu, respectively) of Chinese Risk Screening Values for Soil Contamination of Agricultural Land (GB 15618-2018 2018) or the refereed critical value (≤800 and ≤200 mg kg–1 for F and Cl, respectively) based on Chinese research.  The concentrations of the elements Hg, Cd, Cu, F and Cl  in the leachate of ASR detected by the extraction tests also exceed the limits (Class IV–V) of the Chinese Standard for Groundwater Quality (GB/T 14848-2017 2017).  Based on the above results, it is suggested that ASR without any pretreatment for reducing harmful pollutants should not be used for soil remediation or conditioning of farmlands, to ensure soil health, food safety and environmental quality. 
    Crop Science
    OsHemA gene, encoding glutamyl-tRNA reductase (GluTR) is essential for chlorophyll biosynthesis in rice (Oryza sativa)
    ZENG Zhao-qiong, LIN Tian-zi, ZHAO Jie-yu, ZHENG Tian-hui, XU Le-feng, WANG Yi-hua, LIU Ling-long, JIANG Ling, CHEN Sai-hua, WAN Jian-min
    2020, 19(3): 612-623.  DOI: 10.1016/S2095-3119(19)62710-3
    Abstract ( )   PDF in ScienceDirect  
    Chlorophyll (Chl) biosynthesis is essential for photosynthesis and plant growth.  Glutamyl-tRNA reductase (GluTR) catalyzes glutamyl-tRNA into glutamate-1-semialdehyde (GSA) and initiates the chlorophyll biosynthesis.  Even though the main role of GluTR has been established, the effects caused by natural variations in its corresponding gene remain largely unknown.  Here, we characterized a spontaneous mutant in paddy field with Chl biosynthesis deficiency, designated as cbd1.  With intact thylakoid lamellar structure, the cbd1 plant showed light green leaves and reduced Chl and carotenoids (Cars) content significantly compared to the wild type.  By map-based gene cloning, the mutation was restricted within a 57-kb region on chromosome 10, in which an mPingA miniature inverted-repeat transposable element (MITE) inserted in the promoter region of OsHemA gene.  Both leaf color and the pigment contents in cbd1 were recovered in a complementation test, confirming OsHemA was responsible for the mutant phenotype.  OsHemA was uniquely predicted to encode GluTR and its expression level was dramatically repressed in cbd1.  Transient transformation in protoplasts demonstrated that GluTR localized in chloroplasts and a signal peptide exists in its N-terminus.  A majority of Chl biosynthesis genes, except for POR and CHLG, were down-regulated synchronously by the repression of OsHemA, suggesting that an attenuation occurred in the Chl biosynthesis pathway.  Interestingly, we found major agronomic traits involved in rice yield were statistically unaffected, except for the number of full grains per panicle was increased in cbd1.  Collectively, OsHemA plays an essential role in Chl biosynthesis in rice and its weak allele can adjust leaf color and Chls content without compromise to rice yield.
    Identification of QTL for adult plant resistance to stripe rust in bread wheat line C33
    LUO Jiang-tao, ZHENG Jian-min, WAN Hong-shen, YANG Wu-yun, LI Shi-zhao, PU Zong-jun
    2020, 19(3): 624-631.  DOI: 10.1016/S2095-3119(19)62638-9
    Abstract ( )   PDF in ScienceDirect  
    Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious disease in bread wheat (Triticum aestivum L.).  Identification and use of adult plant resistance (APR) resources are important for stripe rust resistance breeding.  Bread wheat line C33 is an exotic germplasm that has shown stable APR to stripe rust for more than 10 years in Sichuan Province of China.  Here, 183 recombinant inbred lines (RILs) derived from the cross between C33 and a susceptible line X440 were genotyped with diversity arrays technology (DArT) markers to identify resistance quantitative trait locus (QTL).  Field trials were conducted in five years at Chengdu and Xindu of Sichuan Province, using maximum disease severity (MDS) as stripe rust reaction phenotypes.  A total of four quantitative trait loci (QTLs) were detected, respectively designed as QYr.saas-3AS, QYr.saas-5AL, QYr.saas-5BL, and QYr.saas-7DS, explaining 4.14–15.21% of the phenotypic variances.  QYr.saas-5BL and QYr.saas-7DS were contributed by C33.  However, the level for stripe rust resistance contributed by them was not strong as C33, suggesting the presence of other unidentified QTLs in C33.  QYr.saas-7DS corresponded to Yr18 and QYr.saas-5BL remains to be formally named.  The RIL lines carrying combinations QYr.saas-5AL, QYr.saas-5BL, and QYr.saas-7DS showed comparability resistance with C33.  The present study provides resources to pyramid diverse genes into locally adapted elite germplasm to improve the stripe rust resistance of bread wheat.
    Plant regeneration via protoplast electrofusion in cassava
    WEN Feng, SU Wen-pan, ZHENG Hua, YU Ben-chi, MA Zeng-feng, ZHANG Peng, GUO Wen-wu
    2020, 19(3): 632-642.  DOI: 10.1016/S2095-3119(19)62711-5
    Abstract ( )   PDF in ScienceDirect  
    Protoplast electrofusion between callus protoplasts of cultivar TMS60444 and mesophyll protoplasts of cultivar SC8 was performed as an approach for the genetic improvement of cassava. The fusion products were subsequently cultured in protoplast culture medium (TM2G) with gradual dilution for approximately 1–2 months.  Then the protoplast-derived compact calli were transferred to suspension culture medium (SH) for suspension culture.  The cultured products developed successively into embryos, mature embryos, and shoots on somatic embryo emerging medium (MSN), embryo maturation medium (CMM), and shoot elongation medium (CEM), respectively.  And the shoots were then rooted on Murashige and Skoog (1962) medium (MS).  Sixty-six cell lines were obtained and 12 of them developed into plantlets.  Based on assessment of ploidy level and chromosome counting, four of these plantlets were tetraploid and the remaining eight were diploid.  Based on assessment of ploidy level and simple sequence repeat (SSR) analysis, nine tetraploid cell lines, one diploid variant plant line and nine variant cell lines were obtained.  The diploid variant plant line and the nine variant cell lines all showed partial loss of genetic material compared to that of the parent TMS60444, based on SSR patterns.  These results showed that some new germplasm of cassava were created.  In this study, a protocol for protoplast electrofusion was developed and validated.  Another important conclusion from this work is the confirmation of a viable protocol for the regeneration of plants from cassava protoplasts.  Going forward, we hope to provide technical guidance for cassava tissue culture, and also provide some useful inspiration and reference for further genetic improvement of cassava.
    Putrescine, spermidine, and spermine play distinct roles in rice salt tolerance
    Md Azizul ISlam, PANG Jin-huan, MENG Fan-wei, LI Ya-wen, XU Ning, YANG Chao, LIU Jun
    2020, 19(3): 643-655.  DOI: 10.1016/S2095-3119(19)62705-X
    Abstract ( )   PDF in ScienceDirect  
    Polyamines (PAs) play diverse roles in plant growth and development, as well as responses to environmental stimuli.  In this study, the effects of PAs on rice salt tolerance were investigated.  Salt stress resulted in the alteration of endogenous PAs levels in rice roots and leaves, where spermidine (Spd) and spermine (Spm) contents were increased, and putrescine (Put) content was decreased.  RT-qPCR analysis revealed that PAs biosynthesis-related genes ADC1, ODC, and Arginase were significantly downregulated by salt treatment; however, SAMDC transcription was significantly upregulated.  Exogenous Spm enhanced rice salt tolerance remarkably; however, exogenous Put and Spd undermined rice salt tolerance.  Transgenic rice plants overexpressing SAMDC display a higher ratio of Spm/(Put+Spd) and enhanced salt tolerance.  Salt stress also increased polyamine oxidase activities in rice, resulting in elevated reactive oxygen species (ROS) production.  Our findings revealed that accumulation of Put and Spd substantially reduced salt tolerance in rice, likely by facilitating ROS production; whereas, conversion of Put and Spd to Spm contributes to rice salt tolerance.
    Effects of salt and nitrogen on physiological indices and carbon isotope discrimination of wheat cultivars in the northeast of Iran
    2020, 19(3): 656-667.  DOI: 10.1016/S2095-3119(19)62629-8
    Abstract ( )   PDF in ScienceDirect  
    In order to study the effects of different levels of salt stress and nitrogen (N) on physiological mechanisms, carbon isotope discrimination (?13C), and yield of two wheat cultivars (cv.), a two-year field experiment was carried out during 2013–2015.  The treatments included three levels of salt stress (1.3, 5.2, and 10.5 dS m–1), three levels of N (50, 100, and 150 kg N ha–1), and two wheat cultivars, Bam and Toos.  Under salt stress, N application (100 and 150 kg N ha–1) produced a significant effect on both cultivars with respect to physiological traits, i.e., net photosynthetic rate (Pn), stomatal conductance (gs), chlorophyll index (CI), Na+/K+ ratio as well as the grain yield (GY).  The salt-tolerant and -sensitive cultivars exhibited the maximum values of physio-biochemical and yield attributes at 100 and 150 kg N ha–1, respectively.  The results of ?13C showed a significant difference (P<0.001) between wheat cultivars under the control and salt stress.  According to our result, salt-tolerant cultivar Bam seems to be more efficient in terms of higher GY, Pngs, CI, and lower Na+/K+ ratio as well as higher Δ13C as compared with salt-sensitive cultivar Toos, under salt stress.  Therefore, a significant positive correlation that observed between Δ13C and GY, indicated that Δ13C may be an effective index for indirect selection of yield potential in wheat under irrigation regimes with saline water.
    Quantitative design of yield components to simulate yield formation for maize in China
    HOU Hai-peng, MA Wei, Mehmood Ali NOOR, TANG Li-yuan, LI Cong-feng, DING Zai-song, ZHAO Ming
    2020, 19(3): 668-679.  DOI: 10.1016/S2095-3119(19)62661-4
    Abstract ( )   PDF in ScienceDirect  
    Maize (Zea mays L.) stands prominently as one of the major cereal crops in China as well as in the rest of the world.  Therefore, predicting the growth and yield of maize for large areas through yield components under high-yielding environments will help in understanding the process of yield formation and yield potential under different environmental conditions.  This accurate early assessment of yield requires accuracy in the formation process of yield components as well.  In order to formulate the quantitative design for high yields of maize in China, yield performance parameters of quantitative design for high grain yields were evaluated in this study, by utilizing the yield performance equation with normalization of planting density.  Planting density was evaluated by parameters including the maximum leaf area index and the maximum leaf area per plant.  Results showed that the variation of the maximum leaf area per plant with varying plant density conformed to the Reciprocal Model, which proved to have excellent prediction with root mean square error (RMSE) value of 5.95%.  Yield model estimation depicted that the best optimal maximum leaf area per plant was 0.63 times the potential maximum leaf area per plant of hybrids.  Yield performance parameters for different yield levels were quantitatively designed based on the yield performance equation.  Through validation of the yield performance model by simulating high yields of spring maize in the Inner Mongolia Autonomous Region and Jilin Province, China, and summer maize in Shandong Province, the yield performance equation showed excellent prediction with the satisfactory mean RMSE value (7.72%) of all the parameters.  The present study provides theoretical support for the formulation of quantitative design for sustainable high yield of maize in China, through consideration of planting density normalization in the yield prediction process, providing there is no water and nutrient limitation.
    Architecture of stem and branch affects yield formation in short season cotton
    ZHANG Xiang, RUI Qiu-zhi, LI Yuan, CHEN Yuan, CHEN Yuan, ZHANG Xi-ling, CHEN De-hua, SONG Mei-zhen
    2020, 19(3): 680-689.  DOI: 10.1016/S2095-3119(19)62626-2
    Abstract ( )   PDF in ScienceDirect  
    The cotton direct seeding after wheat (rape) harvested is under trial and would be the future direction at the Yangtze River Valley region of China.  The objective of this study was to quantify the effects of branch and stem architecture on cotton yield and identify the optimal cotton architecture to compensate the yield loss due to the reduction of individual production capacity under high planting density in the direst seeding after wheat harvested cropping system.  The characteristics of the stem and branch architecture and the relationships between architecture of the stem and branch with yield formation were studied on eight short season cotton cultivars during 2015 and 2016 cotton growth seasons.  Based on the two years results, three cultivars with different architectures of stem and branch were selected to investigate the effect of mepiquat chloride (MC) application on the architecture of the stem and branch, boll retention, and the yield in 2017.  Significant differences were observed on plant height, all fruiting nodes to branches ratio (NBR) in the cotton plant, and the curvature of the fruiting branch (CFB) among the studied cultivars.  There were three types of stem and fruiting branch structures: Zhong425 with stable and suitable plant height and NBR (about 90 cm and 2.5, respectively), high CFB (more than 10.0), and high boll retention speed and seed cotton yield; Siyang 822 with excessive plant height and NBR, low CFB, and low boll retention speed and seed cotton yield; and other studied cultivars with unstable structure of stem and branch, boll retention speed, and seed cotton yield across years.  And MC application could promote the appropriate plant height and NBR and high CFB and thus resulted in high boll retention speed and the yield.  The results suggested that the suitable plant height and NBR (about 90 cm and 2.5 respectively), and high CFB (more than 10.0), which was related to both genotype and cultural practice, could promote the higher boll retention speed and seed cotton yield.
    Response and adaptation to the accumulation and distribution of photosynthetic product in peanut under salt stress
    ZHANG Guan-chu, DAI Liang-xiang, DING Hong, CI Dun-wei, NING Tang-yuan, YANG Ji-shun, ZHAO Xin-hua, YU Hai-qiu, ZHANG Zhi-meng
    2020, 19(3): 690-699.  DOI: 10.1016/S2095-3119(19)62608-0
    Abstract ( )   PDF in ScienceDirect  
    To clarify the response and adaptability of peanut under salt stress, Huayu 25 was used as the material, and non-salt stress (CK), 0.15% salt stress (S1), and 0.3% salt stress (S2) were applied as three treatments.  The study analysed the effects of salt stress on photosynthetic characteristics, photosynthetic substances accumulation and distribution as well as the ecological adaptability of peanuts.  The results showed that net photosynthetic rate (Pn), SPAD value, leaf area, and peanut yield were reduced under salt stress.  Pn in CK was 13.71 and 28.72% higher than that in S1 and S2 at the 50th day after planting, respectively.  At the same growth period, the SPAD value among treatments was ranked as follows: CK>S1>S2.  The 100-pod mass, 100-kernel mass, kernel rate to pod, and pod mass per plant were reduced under salt stress, and the trend was CK>S1>S2.  The distribution proportion of dry matter in different organs of peanut plant was changed to adapt to such stress.  Roots under salt stress intensively distributed in a 0–40 cm soil layer for salt resistance.  Dry mass proportion in stems and pods increased during the vegetative stage and early period of reproductive stage, respectively.  The maximum growth rates of the pod volume, pod dry weight, and seed kernel dry weight all declined, and the pod and kernel volume at harvest were reduced, improving the seed plumpness under salt stress.  This finding could be useful in growing peanut in saline soil.
    Detection of seven phytohormones in peanut tissues by ultra-high-performance liquid chromatography-triple quadrupole tandem mass spectrometry
    WANG Hai-xia, WANG Ming-lun, WANG Xiu-zhong, DING Yu-long
    2020, 19(3): 700-708.  DOI: 10.1016/S2095-3119(19)62640-7
    Abstract ( )   PDF in ScienceDirect  
    Development of highly sensitive and reliable method for detection of phytohormones is of great significance to study plant hormones and agricultural production.  In this study, an ultra-high-performance liquid chromatography-mass spectrometry/mass spectrometry method was established for separation and quantification of trans-zeatin, trans-zeatin riboside, gibberellin A3, indol-3-acetic acid, salicylic acid, abscisic acid, and jasmonic acid (JA) without any label.  The separation was performed on an Agilent Explus Plus C18 column by using methanol and water as mobile phases with gradient elution.  The target compounds were confirmed and quantified by mass spectrum via positive electrospray ionization for trans-zeatin, trans-zeatin riboside, indole-3-acetic acid, and via negative electrospray ionization for gibberellin3, salicylic acid, abscisic acid, and JA.  The limits of detection ranged from 0.0127 ng L–1 for gibberellin A3 (GA3) to 33.26 ng L–1 for JA and were lower than the currently reported values in literature.  The proposed method was applied for qualitative and quantitative analyses of phytohormones in peanut gynophores and pods.  The recoveries of the spiked phytohormones ranged from 80.20 to 102.56%.  The contents of seven endogenous hormones varied specifically in different development stages of peanuts.  This study provides a highly sensitive and selective detection method for hormones and elucidates the growth and development of the gynophore and peanut fruit, which are controlled by seven endogenous hormones.
    Physiological evaluation of nitrogen use efficiency of different apple cultivars under various nitrogen and water supply conditions
    WANG Qian, LIU Chang-hai, HUANG Dong, DONG Qing-long, LI Peng-min, Steve van NOCKER, MA Feng-wang
    2020, 19(3): 709-720.  DOI: 10.1016/S2095-3119(19)62848-0
    Abstract ( )   PDF in ScienceDirect  
    Nitrogen (N) deficiency is a common problem for apple (Malus×domestica) production in arid regions of China.  However, N utilization efficiency (NUE) of different apple cultivars grown under low N conditions in arid regions has not been evaluated. In this study, NUE was assessed for one-year-old seedlings of six apple cultivars, Golden Delicious, Qinguan, Jonagold, Honeycrisp, Fuji and Pink Lady, grafted onto Malus hupehensis Rehd. rootstocks.  Four treatments were used, including control water with control N (CWCN), limited water with control N (LWCN), control water with low N (CWLN) and limited water with low N (LWLN).  Our results showed that growth indices such as biomass, plant height and stem diameter, and photosynthetic rate of all cultivars decreased in the order CWCN>CWLN>LWCN>LWLN.  When subjected to LWLN treatment, Qinguan showed better growth and photosynthetic characters than other tested cultivars.  Additionally, Qinguan and Pink Lady had higher NUE, while Honeycrisp and Jonagold had lower NUE, based on the determination of biomass, photosynthetic parameters, chlorophyll content, the maximal photochemical efficiency of PSII (Fv/Fm), 15N and N contents.
    Growth simulation and yield prediction for perennial jujube fruit tree by integrating age into the WOFOST model
    BAI Tie-cheng, WANG Tao, ZHANG Nan-nan, CHEN You-qi, Benoit MERCATORIS
    2020, 19(3): 721-734.  DOI: 10.1016/S2095-3119(19)62753-X
    Abstract ( )   PDF in ScienceDirect  
    Mathematical models have been widely employed for the simulation of growth dynamics of annual crops, thereby performing yield prediction, but not for fruit tree species such as jujube tree (Zizyphus jujuba).  The objectives of this study were to investigate the potential use of a modified WOFOST model for predicting jujube yield by introducing tree age as a key parameter.  The model was established using data collected from dedicated field experiments performed in 2016–2018.  Simulated growth dynamics of dry weights of leaves, stems, fruits, total biomass and leaf area index (LAI) agreed well with measured values, showing root mean square error (RMSE) values of 0.143, 0.333, 0.366, 0.624 t ha–1 and 0.19, and R2 values of 0.947, 0.976, 0.985, 0.986 and 0.95, respectively.  Simulated phenological development stages for emergence, anthesis and maturity were 2, 3 and 3 days earlier than the observed values, respectively.  In addition, in order to predict the yields of trees with different ages, the weight of new organs (initial buds and roots) in each growing season was introduced as the initial total dry weight (TDWI), which was calculated as averaged, fitted and optimized values of trees with the same age.  The results showed the evolution of the simulated LAI and yields profiled in response to the changes in TDWI.  The modelling performance was significantly improved when it considered TDWI integrated with tree age, showing good global (R2≥0.856, RMSE≤0.68 t ha–1) and local accuracies (mean R2≥0.43, RMSE≤0.70 t ha–1).  Furthermore, the optimized TDWI exhibited the highest precision, with globally validated R2 of 0.891 and RMSE of 0.591 t ha–1, and local mean R2 of 0.57 and RMSE of 0.66 t ha–1, respectively.  The proposed model was not only verified with the confidence to accurately predict yields of jujube, but it can also provide a fundamental strategy for simulating the growth of other fruit trees.
    Plant Protection
    Functional analysis and screening small molecules to RpfF protein in Xanthomonas oryzae involved in rice bacterial blight disease
    Mundla SRILATHA, Naina PATYAL, Madhu Sudhana SADDALA
    2020, 19(3): 735-747.  DOI: 10.1016/S2095-3119(19)62813-3
    Abstract ( )   PDF in ScienceDirect  
    Xanthomonas oryzae pv. oryzae (Xoo) is an important rice pathogen.  This is a vascular pathogen entering the plant via the hydathodes causing rice bacterial blight.  It has been known that most regulation of pathogenicity factor F (RpfF) genes in Xanthomonas regulates virulence in response to the diffusible signal factor (DSF).  The RpfF recognized as an attractive drug target in bacterial rice blight disease.  In this study, we performed the gene-gene interaction of RpfF and pathway functional analysis.  3D structure of RpfF protein was predicted using a homology modelling tool Swiss-Model and refined by molecular dynamics (MD) simulation.  The refined model protein was predicted structural assessment using various tools such as PROCHECK, ERRAT, and VERIFY-3D.  We have collected 2 500 rifampicin analogues from Zinc Database by virtual screening.  The screened compounds were docked into the active site of the RpfF protein using AutoDock Vina in PyRx Virtual Screening Tool.  Furthermore, docking result and in silico ADMET analysis described that the compounds ZINC03056414, ZINC03205310, ZINC08673779, ZINC09100848, ZINC09729566, ZINC11415953, ZINC12810788, ZINC24989313, ZINC27441787 and ZINC32739565 have best binding energies and less toxicity than reference compound.  This study revealed that the active site residues such as HIS-118, HIS-147, THR-148, ARG-179, ASP-207, ARG-240 and THR-244 are key roles in the pathogenicity.  It could be beneficial in the design of small molecule therapeutics or the treatment of rice bacterial blight disease.
    Bacterial extracts and bioformulates as a promising control of fruit body rot and root rot in avocado cv. Hass
    2020, 19(3): 748-758.  DOI: 10.1016/S2095-3119(19)62720-6
    Abstract ( )   PDF in ScienceDirect  
    At least 20–40% of annual losses of avocado crops are caused by pathogenic fungi.  The chemical treatments of these diseases are inefficient, cause environmental pollution and are increasingly restricted by international laws.  This work aimed to assess the biocontrol capacity of a bacterial extract to protect avocado fruits and plants from pathogen infections.  Extracts from the bacterial isolate Serratia sp. ARP5.1 were obtained from liquid fermentations in a biorreactor.  A body rot postharvest infection model with Colletotrichum gloeosporioides on fruits was developed.  Moreover, packaging conditions were simulated using the bacterial extract and the commercial fungicide prochloraz as a positive control.  Additionally, seedlings infections with Phytophthora cinnamomi were performed on two types of avocado (West Indian race and cv. Hass).  The Area Under Disease Progress Curve (AUDPC) was recorded using the bacterial extract and a commercial product with fosetyl-aluminium as treatments.  The bacterial extract significantly reduced infections by C. gloeosporioides on injured avocado fruits at 31.1 µg mL–1.  Intact fruits were also protected against body rot infections at the same concentration and showed no significant differences with the commercial fungicide.  On the other hand, AUDPC in the seedlings was significantly reduced with the extract treatment at 3 µg mL–1 compared to the control.  However, a possible phytotoxicity effect of the extract was evidenced in the seedlings and confirmed by pathogen recovery and tests on Raphanus sativus seedlings.  Finally, formulations of the extracts (emulsion and emulsifiable concentrate) were prepared, and bioactive stability was assessed for 8 wk.  The emulsion formulates demonstrated very stable bioactivity against P. cinnamomi.  The extract and the emulsion formulate showed promising results for the control of avocado pathogens.  New bioproducts based on this type of active principles could be developed for the benefit of avocado industry.
    Regulation of the phytotoxic response of Arabidopsis thaliana to the Fusarium mycotoxin deoxynivalenol
    WANG Yan, YAN Hao, WANG Qi, ZHENG Ran, XIA Kai, LIU Yang
    2020, 19(3): 759-767.  DOI: 10.1016/S2095-3119(19)62741-3
    Abstract ( )   PDF in ScienceDirect  
    Phytopathogenic fungi, such as Fusarium spp., synthesize trichothecene family phytotoxins.  The type B trichothecene, namely deoxynivalenol (DON), is highly prevalent in small-grain cereals, such as wheat, corn and barley.  DON is thought to be a virulence factor allowing plant infections and has an elicitor activity.  We used the model plant Arabidopsis thaliana to evaluate the phytotoxic effects of DON in host plants.  The growth of A. thaliana on media was significantly inhibited by DON.  Moreover, DON induced cell death in detached leaves was observed by trypan blue staining.  This is consistent with the phenomenon of organelle changes observed at the ultrastructural level.  In our study, DON exposure stimulated oxidative bursts in the leaves, resulting in the concomitant down-regulation of antioxidant enzyme defense responses and up-regulation of lipid peroxidation.  In addition, a real-time PCR analysis revealed that the DON treatment rapidly induced the transcription of defense genes, like AtrbohC and AtrbohD, and up-regulated the transcriptional level of the ascorbic acid peroxidase gene.  These results suggested that DON phytotoxicity might result from reactive oxygen species pathways, and that DON production by the plant pathogen Fusarium graminearum can act as an elicitor influencing plant cell fate.
    Prevalence and genetic diversity of grapevine fabavirus isolates from different grapevine cultivars and regions in China
    FAN Xu-dong, ZHANG meng-yan, ZHANG Zun-ping, REN Fang, HU Guo-jun, DONG Ya-feng
    2020, 19(3): 768-774.  DOI: 10.1016/S2095-3119(19)62677-8
    Abstract ( )   PDF in ScienceDirect  
    A total of 288 grapevine samples of 61 different grapevine cultivars, collected from 22 provinces and regions, were analyzed by reverse transcription-PCR (RT-PCR) for the presence of grapevine fabavirus (GFabV).  PCR detection results showed the incidences of GFabV were 12.8% (30/235) and 48.1% (25/52) in the asymptomatic and symptomatic vines, respectively.  The genetic diversity of GFabV isolates was analyzed based on partial nucleotide and encoded amino acid sequences of the RNA1 and RNA2 polyprotein genes.  Phylogenetic analyses of the RNA1 and RNA2 gene sequences divided the GFabV isolates into five well-defined groups.  Groups 1, 2, and 4 comprised only Chinese isolates.  This article represents the first report for the prevalence and genetic diversity of GFabV in grapevines grown in China.
    pH influences the profiles of midgut extracts in Cnaphalocrocis medinalis (Guenée) and its degradation of activated Cry toxins
    YANG Ya-jun, XU Hong-xing, WU Zhi-hong, LU Zhong-xian
    2020, 19(3): 775-784.  DOI: 10.1016/S2095-3119(19)62837-6
    Abstract ( )   PDF in ScienceDirect  
    Midgut extracts play crucial roles in food digestion and detoxification.  We evaluated the effect of pH on the profiles of the midgut extracts in rice leaffolder, Cnaphalocrocis medinalis and the degradation of activated Bt-toxins by the midgut extracts under different pH conditions.  Total protease activity increased slightly with the increase with the simulated pH in the midgut extracts and the maximal protease activity was observed at pH 10.5, while an upward trend was observed as the pH of reaction buffer increased.  Activity of chymotrypsin-like enzymes increased with pH, both in the buffer and midgut extracts, while the activity of trypsin-like enzyme was unaffected.  Degradation of the activated Cry2A by the midgut extracts enhanced as the pH increased.  Cry2A was fully degraded into smaller segments at pH 9.0–10.5.  Activated Cry1C protein at pH 9.0–10.5 was partially degraded by the midgut extracts.  Activated Cry1Aa and Cry1Ac were partially degraded into fragments by the midgut extracts at high pH.  These results will facilitate our further understanding of the interactions between C. medinalis and the Cry toxin.
    Overwintering parasitism is positively associated with population density in diapausing larvae of Chilo suppressalis
    HUANG Xiao-long, JIANG Ting, WU Zhen-ping, ZHANG Wan-na, XIAO Hai-jun
    2020, 19(3): 785-792.  DOI: 10.1016/S2095-3119(19)62815-7
    Abstract ( )   PDF in ScienceDirect  
    The suppression of overwintering population is essential in integrated pest management, but little is known about the biological mortality factors that reduce the overwintering density of Chilo suppressalis.  Here, we examine the parasitism of overwintering larvae, and assume that key parasitoids strengthen the over-wintering population suppression.  The natural parasitism incidence and related dominant parasitoids in overwintering larvae were investigated in two successive winters, in 2015–2016 and 2016–2017.  Parasitism rates were also assessed in larvae collected from 15 different counties in 2016.  The results showed that the parasitism incidence and dominant parasitoids in overwintering C. suppressalis larvae were significantly different for different sampling dates and sites.  Overwintering larvae of C. suppressalis were mainly parasitized by Cotesia chilonis, and less often by Eriborus sinicus and Micrurogaster ssata.  Regression analysis indicated that the natural incidence of parasites in overwintering C. suppressalis larvae was positively correlated with the over-wintering larval density.  The current work provides support for overwintering pest management strategies by showing the effectiveness of parasitoid communities as a bio-mortality factor for suppressing overwintering density.
    Animal Science · Veterinary Medicine
    Genetic parameter estimation and genome-wide association study (GWAS) of red blood cell count at three stages in a Duroc×Erhualian pig population
    NAN Jiu-hong, YIN Li-lin, TANG Zhen-shuang, CHEN Jian-hai, ZHANG Jie, WANG Hai-yan, DU Xiao-yong, LIU Xiang-dong
    2020, 19(3): 793-799.  DOI: 10.1016/S2095-3119(19)62773-5
    Abstract ( )   PDF in ScienceDirect  
    Red blood cells play an essential role in the immune system.  Moreover, red blood cell count (RBC) is an important clinical indicator of various diseases, including anemia, type 2 diabetes and the metabolic syndrome.  Thus, it is necessary to reveal the genetic mechanism of RBC for animal disease resistance breeding.  However, quite a few studies had focused on porcine RBC, especially at different stages.  Thus, studies on porcine RBC at different stages are needed for disease resistant breeding.  In this study, the porcine RBC of 20-, 33-, and 80-day old were measured, and genetic parameter estimation and genome-wide association study (GWAS) were both performed.  As a result, the heritability was about 0.6 at the early stages, much higher than that at 80 days.  Nine novel genome wide significant single nucleotide polymorphisms (SNPs), located at Sus scrofa chromosome (SSC)3, 4, 8, 9, 10 and 15, respectively, were identified.  Further, TGFβ2, TMCC2 and PPP1R15B genes were identified as important candidate genes of porcine red blood cell count.  So different SNPs and candidate genes were found significantly associated with porcine RBC at different stages, suggesting that different genes might play key roles on porcine RBC at different stages.  Overall, new evidences were offered in this study for the genetic bases of animal RBC, and that the SNPs and candidate genes would be useful for disease resistant breeding of pig.
    Expression and contribution of microphthalmia-associated transcription factor to the melanin deposition in Liancheng white ducks
    XIN Qing-wu, MIAO Zhong-wei, LIU Zhao-yuan, LI Li, ZHANG Lin-li, ZHU Zhi-ming, ZHANG Zheng-hong, ZHENG Nen-zhu, WANG Zheng-chao
    2020, 19(3): 800-809.  DOI: 10.1016/S2095-3119(19)62736-X
    Abstract ( )   PDF in ScienceDirect  
    The present study investigates the expression of microphthalmia-associated transcription factor (MITF) and its contribution to the melanin deposition in Liancheng white ducks.  Nested PCR was used to clone the MITF gene sequence from the skin tissue of female Liancheng white ducks.  Ultraviolet spectrophotometry was used to detect the melanin deposition.  MITF mRNA expression and melanin deposition in different tissues and organs were detected and their correlation was analyzed.  The MITF gene (GenBank number: MG516570) was 1 323 bp in length, contains a complete CDS region (34–1 323 bp) and codes 429 amino acids with 100% homology to the MITF of Anas platyrhynchos and over 95% homology to those of Gallus gallus and Coturnix japonica.  Genetic evolution analysis reveals a close relationship of Liancheng white ducks with A. platyrhynchos, and also to lesser extents with Anser cygnoides, silky fowl and G. gallus, as well as Sus scrofa, Ovis aries and other mammals.  Real-time quantitative PCR (qPCR) analysis demonstrated that MITF was expressed in skin, gizzard, liver, kidney and muscle, and of these tissues, its expression was the highest in the skin tissue (skin>gizzard>liver>kidney>muscle).  Ultraviolet spectrophotometry showed that melanin deposition was positively correlated with the MITF expression level in these five tissues and organs (P<0.05).  Together, these results demonstrated a tissue-specific pattern of MITF expression and a positive correlation between MITF expression and melanin deposition, indicating that MITF expression may contribute to the melanin deposition in Liancheng white ducks.
    Effects of yeast and yeast cell wall polysaccharides supplementation on beef cattle growth performance, rumen microbial populations and lipopolysaccharides production
    PENG Quan-hui, CHENG Long, KANG Kun, Tian Gang, Mohammad AL-MAMUN, XUE Bai, WANG Li-zhi, ZOU Hua-wei, Mathew Gitau GICHEHA, WANG Zhi-sheng
    2020, 19(3): 810-819.  DOI: 10.1016/S2095-3119(19)62708-5
    Abstract ( )   PDF in ScienceDirect  

    This experiment was conducted to investigate the effects of live yeast and yeast cell wall polysaccharides on growth performance, rumen function and plasma lipopolysaccharides (LPS) content and immunity parameters of beef cattle.  Forty Qinchuan cattle were randomly assigned to one of four treatments with 10 replicates in each treatment.  The dietary treatments were: control diet (CTR), CTR supplemented with 1 g live yeast (2×1010 live cell g–1 per cattle per day (YST1), CTR supplemented with 2 g live yeast per cattle per day (YST2) and CTR supplemented with 20 g of yeast cell wall polysaccharides (30.0%≤β-glucan≤35.0%, and 28.0%≤mannanoligosaccharide≤32.0%) per cattle per day (YCW).  The average daily gain was higher (P=0.023) and feed conversion ratio was lower (P=0.042) for the YST2 than the CTR.  The digestibility of neutral detergent fiber (P=0.039) and acid detergent fiber (P=0.016) were higher in yeast supplemented groups.  The acetic acid:propionic acid of the YST2 was lower compared with the CTR (P=0.033).  Plasma LPS (P=0.032), acute phase protein haptoglobin (P=0.033), plasma amyloid A (P=0.015) and histamine (P=0.038) were lower in the YST2 compared with the CTR.  The copies of fibrolytic microbial populations such as Fibrobacter succinogenes S85, Ruminococcus albus 7 and Ruminococcus flavefaciens FD-1 of the YST2 were higher (P<0.001), while the copies of typical lactate producing bacteria Streptococcus bovis JB1 was lower (P<0.001) compared with the CTR.  Little differences were observed between the CTR, YST1 and YCW in growth performance, ruminal fermentation characteristics, microbial populations, immunity indices and total tract nutrient digestibility.  It is concluded that the YST2 could promote fibrolytic microbial populations, decrease starch-utilizing bacteria, reduce LPS production in the rumen and LPS absorption into plasma and decrease inflammatory parameters, which can lead to an improvement in growth performance in beef cattle. 

    Temporal dynamics of nutrient balance, plasma biochemical and immune traits, and liver function in transition dairy cows
    SUN Bo-fei, CAO Yang-chun, CAI Chuan-jiang, YU Chao, LI Sheng-xiang, YAO Jun-hu
    2020, 19(3): 820-837.  DOI: 10.1016/S2095-3119(20)63153-7
    Abstract ( )   PDF in ScienceDirect  
    The objective of this study was to analyze the dynamics of nutrient balance, physiological biomarkers and comprehensive indexes associated with metabolism and function of organs in transition cows. Fourteen transition cows were used for this research. Dietary intake was recorded daily, and samples of the diet, venous blood and milk were collected for measurements. The balance values of net energy for lactation (NEL ), metabolizable protein (MP), and metabolizable glucose (MG) were calculated, and regression analysis and calculation of comprehensive indexes were performed. Accordingly, the prepartum cows presented positive balances of NEL , MP, and MG, while severe negative balances were found during the postpartum period. Dynamic changes of energy metabolism, nutrient mobilization, liver function, anti-oxidative status and immune response, as indicated by blood biomarkers and modified comprehensive indexes, were out of sync with the calculated balance values, but they were closely related to the day relative to calving. Compared with the 21 d prepartum, the plasma concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyric acid (BHBA) were significantly increased around and after calving (P<0.05), and similar variation tendency was observed for most of other parameters. The occurrence of parturition and the initiation of lactation were more responsible for the negative balances of nutrients in transition dairy cows. Although negative balances of NEL , MP and MG were not observed using the assessment model, the nutritional strategies should be applied before calving, because metabolic adaptations had been validated during the prepartum period. In addition, it was plausible to conclude that the decline of hepatic metabolism, defense function and insulin sensitivity are critical causes of metabolic dysfunction.
    The effect of lactic acid bacteria inoculums on in vitro rumen fermentation, methane production, ruminal cellulolytic bacteria populations and cellulase activities of corn stover silage
    GUO Gang, SHEN Chen, LIU Qiang, ZHANG Shuan-lin, SHAO Tao, WANG Cong, WANG Yong-xin, XU Qing-fang, HUO Wen-jie
    2020, 19(3): 838-847.  DOI: 10.1016/S2095-3119(19)62707-3
    Abstract ( )   PDF in ScienceDirect  
    The objective of this study was to investigate the effect of lactic acid bacteria (LAB) inoculums on fermentation quality and in vitro digestibility of corn stover silage. Corn stover was ensiled without (control) or with Lactobacillus plantarum (LP), Enterococcus faecalis (EF), and Enterococcus mundtii (EM) for 45 days. The fermentation characteristics were assessed, and subsequent in vitro dry matter digestibility (DM-D), neutral detergent fiber digestibility (NDF-D), volatile fatty acids (VFA), methane (CH4 ) production, cellulolytic bacteria proportions and their activities per corn stover silage were also determined. There was no significant difference (P>0.05) among the silage pH, lactic acid, crude protein (CP), water soluble carbohydrates (WSC) and lignocelluloses contents of different treatments. The relative proportions of Ruminococcus flavefaciens and Fibrobacter succinogenes, carboxymethyl-ocellulose and β-glycosidase activities, DM-D, NDF-D, and VFA production of in vitro incubation was higher (P<0.05) for silages inoculated with LP and EF than those of the control silage. Silage inoculated with LP showed the lowest (P<0.05) CH4 production per unit yield of VFA, which was positively corresponded to the lowest (P<0.05) ratio of acetate to propionate. In summary, the ensiling fermentation quality and subsequent utilization of corn stover silage were efficiently improved by inoculated with L. plantarum.
    Agro-ecosystem & Environment
    Change of soil productivity in three different soils after long-term field fertilization treatments
    LIU Kai-lou, HAN Tian-fu, HUANG Jing, ZHANG Shui-qing, GAO Hong-jun, ZHANG Lu, Asad SHAH, HUANG Shao-min, ZHU Ping, GAO Su-duan, MA Chang-bao, XUE Yan-dong, ZHANG Hui-min
    2020, 19(3): 848-858.  DOI: 10.1016/S2095-3119(19)62742-5
    Abstract ( )   PDF in ScienceDirect  
    Soil productivity (SP) without external fertilization influence is an important indicator for the capacity of a soil to support crop yield. However, there have been difficulties in estimating values of SPs for soils after various long-term field treatments because the treatment without external fertilization is used but is depleted in soil nutrients, leading to erroneous estimation. The objectives of this study were to estimate the change of SP across different cropping seasons using pot experiments, and to evaluate the steady SP value (which is defined by the basal contribution of soil itself to crop yield) after various longterm fertilization treatments in soils at different geographical locations. The pot experiments were conducted in Jinxian of Jiangxi Province with paddy soil, Zhengzhou of Henan Province with fluvo-aquic soil, and Gongzhuling of Jilin Province with black soils, China. Soils were collected after long-term field fertilization treatments of no fertilizer (control; CK-F), chemical fertilizer (NPK-F), and combined chemical fertilizer with manure (NPKM-F). The soils received either no fertilizer (F0) or chemical fertilizer (F1) for 3–6 cropping seasons in pots, which include CK-P (control; no fertilizer from long-term field experiments for pot experiments), NPK-P (chemical fertilizer from long-term field experiments for pot experiments), and NPKM-P (combined chemical and organic fertilizers from long-term field experiments for pot experiments). The yield data were used to calculate SP values. The initial SP values were high, but decreased rapidly until a relatively steady SP was achieved at or after about three cropping seasons for paddy and fluvo-aquic soils. The steady SP values in the third cropping season from CK-P, NPK-P, and NPKM-P treatments were 37.7, 44.1, and 50.0% in the paddy soil, 34.2, 38.1, and 50.0% in the fluvo-aquic soil, with the highest value observed in the NPKM-P treatment for all soils. However, further research is required in the black soils to incorporate more than three cropping seasons. The partial least squares path mode (PLS-PM) showed that total N (nitrogen) and C/N ratio (the ratio of soil organic carbon and total N) had positive effects on the steady SP for all three soils. These findings confirm the significance of the incorporation of manure for attaining high soil productivity. Regulation of the soil C/N ratio was the other main factor for steady SP through fertilization management.
    Translocation and recovery of 15N-labeled N derived from the foliar uptake of 15NH3 by the greenhouse tomato (Lycopersicon esculentum Mill.)
    HUANG Hui-ying, LI Huan, XIANG Dan, LIU Qing, LI Fei, LIANG Bin
    2020, 19(3): 859-865.  DOI: 10.1016/S2095-3119(19)62670-5
    Abstract ( )   PDF in ScienceDirect  
    In order to completely evaluate ammonia emission from greenhouse vegetable fields, crop canopy absorption should not be neglected.  The foliar uptake of NH3 applied at two growth stages and the subsequent 15N-labeled N translocation to other plant components were investigated under greenhouse conditions using chambers covered with the soil of a tomato field.  Treatments comprised three NH3-N application rates (70, 140, and 210 mg/plot) using 15N-labeled ammonium sulfate.  Plants were harvested immediately after exposure for 24 h, and the total N concentrations and 15N/14N ratios were determined.  With increased NH3 concentration, total 15NH3-N absorption increased considerably, whereas the applied 15NH3-N uptake decreased gradually.  The tomato plants absorbed 33–38% and 24–31% of the 15NH3-N generated at the anthesis and fruit growth stages, respectively.  A total of 71–80% of the recovered NH3 was observed in the leaves and 20–30% of the recovered NH3 was remobilized to other components.  Among them, an average of 10% of the absorbed 15NH3-N was transferred into the tomato fruits.  All these results indicated the potential of the tested tomatoes for the foliar uptake of atmospheric 15NH3 and the distribution of 15N-labeled vegetative N among different plant components.  The results are of great importance for the complete evaluation of nitrogen use efficiency in the greenhouse tomato fields.
    A comprehensive analysis of the response of the fungal community structure to long-term continuous cropping in three typical upland crops
    LIU Hang, PAN Feng-juan, HAN Xiao-zeng, SONG Feng-bin, ZHANG Zhi-ming, YAN Jun, XU Yan-li
    2020, 19(3): 866-880.  DOI: 10.1016/S2095-3119(19)62630-4
    Abstract ( )   PDF in ScienceDirect  
    Certain agricultural management practices are known to affect the soil microbial community structure; however, knowledge of the response of the fungal community structure to the long-term continuous cropping and rotation of soybean, maize and wheat in the same agroecosystem is limited.  We assessed the fungal abundance, composition and diversity among soybean rotation, maize rotation and wheat rotation systems and among long-term continuous cropping systems of soybean, maize and wheat as the effect of crop types on fungal community structure.  We compared these fungal parameters of same crop between long-term crop rotation and continuous cropping systems as the effect of cropping systems on fungal community structure.  The fungal abundance and composition were measured by quantitative real-time PCR and Illumina MiSeq sequencing.  The results revealed that long-term continuous soybean cropping increased the soil fungal abundance compared with soybean rotation, and the fungal abundance was decreased in long-term continuous maize cropping compared with maize rotation.  The long-term continuous soybean cropping also exhibited increased soil fungal diversity.  The variation in the fungal community structure among the three crops was greater than that between long-term continuous cropping and rotation cropping.  Mortierella, Guehomyces and Alternaria were the most important contributors to the dissimilarity of the fungal communities between the continuous cropping and rotation cropping of soybean, maize and wheat.  There were 11 potential pathogen and 11 potential biocontrol fungi identified, and the relative abundance of most of the potential pathogenic fungi increased during the long-term continuous cropping of all three crops.  The relative abundance of most biocontrol fungi increased in long-term continuous soybean cropping but decreased in long-term continuous maize and wheat cropping.  Our results indicate that the response of the soil fungal community structure to long-term continuous cropping varies based upon crop types.
    Short Communication
    Range expansion of the invasive cotton mealybug, Phenacoccus solenopsis Tinsley: An increasing threat to agricultural and horticultural crops in China
    WANG Yu-sheng, DAI Tian-mei, TIAN Hu, WAN Fang-hao, ZHANG Gui-fen
    2020, 19(3): 881-885.  DOI: 10.1016/S2095-3119(19)62765-6
    Abstract ( )   PDF in ScienceDirect  
    The globally invasive cotton mealybug Phenacoccus solenopsis Tinsley, has recently invaded several Chinese regions, and continues to expand its range.  This mealybug is a polyphagous insect pest, with at least 200 host plants from 63 families, including cotton, food crops, fruits, ornamental plants, tobacco, and vegetables.  Here, we describe the first finding of P. solenopsis in Shandong Province, and investigate the abundances of its natural enemies (predator Coccinella septempunctata L. and parasitoid Aenasius bambawalei Hayat).  All three species were detected from ornamental and weed species in Linyi, Shandong, in September 2018, and were positively identified using DNA barcoding.  BLAST analysis revealed significant identity (99.38–100%) between sequences of P. solenopsis obtained in this study and those published in the past.  This invasive pest represents a major potential threat to agri-horticulture in Shandong, which is a key province of China for production and export of many vegetables, flowers, fruits, and other crops.  This mealybug species has a wide range of potential distribution in Shandong and is easily dispersed with agricultural and horticultural transport products.  Further monitoring and management strategies are required to limit the spread of this pest species.