Table of Content

16 March 2020, Volume 53 Issue 6

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Transcriptome Research of Erect and Short Panicle Mutant esp in Rice

KunNeng ZHOU,JiaFa XIA,Peng YUN,YuanLei WANG,TingChen MA,CaiJuan ZHANG,ZeFu LI

Scientia Agricultura Sinica. 2020, 53(6):  1081-1094.  doi:10.3864/j.issn.0578-1752.2020.06.001

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【Objective】In this study, we aimed to identify the ESP gene, whose mutation caused a phenotype, namely erect and short panicle, and to determine its regulatory role in the gene network that controls the related agronomic traits (e.g., plant types and panicle length).【Method】In this study, agronomic traits, such as plant height, panicle length and grain length at mature stages, were used as phenotypic marks to trace the esp mutant. Individuals carrying mutant phenotypes were selected from the F₂ population to cross with indica and japonica for further gene mapping and genome sequencing that were used to map the potential mutation region/sites. The bioinformatics software was used to analyze phylogenetic tree and gene expression. The total RNAs isolated from wild type and mutants were used for transcriptome RNA-seq analysis. The differential expressed genes and expression levels of genes related to plant hormone signal transduction and protein processing in endoplasmic reticulum were analyzed by GO software and KEGG database. The transcriptome data were verified by qRT-PCR.【Result】Phenotypic analysis showed that the esp mutant exhibited a erect panicle architecture. The plant height, panicle length, grain length and the number of spikelets per panicle were decreased in the esp mutants, when compared to wild type control, whereas grain width and the 1 000-grain weight were increased, although no obvious difference in the number of effective panicles between mutants and control. The ESP gene was mapped to a 7.58 Mb interval between markers C7-11 and C7-14 on the long arm of rice 7th chromosome by using the F₂ population of esp mutant and PA64. Genome sequencing demonstrated that a single nucleotide change (G to A) at the junction of 6th intron and 7th exon of LOC_Os07g42410, which led to a splicing defect, causing premature protein translation. The ESP was allelic to OsDEP2/OsEP2. Phylogenetic analysis revealed that the ESPs are widely present in monocot and dicot plants. Expression analysis predicted that ESP gene was highly expressed in stem, inflorescence, pistil, glumelle, lemma and ovary, and the expression level was gradually decreased with the ovary inflation. Transcriptome RNA-seq analysis of young panicle identified 630 differential expressed genes in esp mutants versus wild type, including 235 up-regulated and 395 down-regulated. GO and qRT-PCR analysis revealed that genes involved in plant hormone signal transduction and protein processing in endoplasmic reticulum were misregulated in esp mutants.【Conclusion】The ESP gene was allelic to OsDEP2/OsEP2, the mutation of which leads to multiple phenotypes, such as decreased plant height and shorter panicle length. Transcriptome analysis suggested that the ESP gene might affect plant development by regulating genes expression associated with plant hormone signal transduction and protein processing in endoplasmic reticulum.

Analysis of the Current Status of Protection of Maize Varieties in China

Yang YANG,HongLi TIAN,HongMei YI,YaWei LIU,Jie REN,Rui WANG,Lu WANG,JiuRan ZHAO,FengGe WANG

Scientia Agricultura Sinica. 2020, 53(6):  1095-1107.  doi:10.3864/j.issn.0578-1752.2020.06.002

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【Objective】Protection of new varieties of plants can protect the legal rights of seed breeders, promote industrialization and modernization of the seed industry, and as a result further develop agriculture and guarantee food security of the country. The paper aims at a better understanding of current status of maize seed industry in China from the aspect of intellectual property rights, by analyzing the data of maize variety protection and the effort of protection of new varieties of plants carried out on Zea mays L..【Method】The paper summarized in one table the maize variety data of protection of new varieties of plants during the last 20 years, acquired through material search, collection and data verification from sources such as variety rights notices, by statistics analysis of 9 kinds of maize variety protection. 【Result】 From 1999 to 2018, the applications for 7 570 maize varieties have been accepted for the protection of new varieties of plants and those for 3 609 maize varieties have been granted. The ratio of applications for hybrids to those for inbred lines is 1.33 to 1, yet the ratio of granted numbers is 1.88 to 1. By the end of 2018, protection of 3 060 maize varieties are in process of application, that of 2 448 already authorized, that of 901 in process of withdrawal, and that of 1 161 terminated, with an average evaluation time of 3.9 years. 1 340 units or persons filed applications, with seeds enterprises and scientific research institutes taking up 65.0% and 28.4%, respectively; 739 organizations or individuals has been granted with maize variety protection as the owner of such variety, among which, seeds enterprises and scientific research institutions take up a proportion of 59.7% and 33.9%, respectively. Beijing tops among all the provinces in the numbers of both applicators and authorization holders, while none shows in Jiangxi, Qinghai, Tibet, Hong Kong, Macao and Taiwan.【Conclusion】Maize is the species with the largest number of applications and authorizations for protection of new varieties of plants in China. Maize varieties protection applications show, in terms of time, the trend of three distinct periods, i.e. the starting, stable and blowout periods, and the authorizations show the trend of four phases, i.e. unstable, peak, trough and steadily-increasing phases. In terms of space, it shows the trend of a majority of applicants and authorized organizations or individuals located in Northeast China, North China and the Huang-Huai-Hai region. Hybrids take up more proportion in both application and authorization, but the attention to inbred lines keeps increasing year by year. The seeds enterprises are the major applicators and authorized organizations, yet the scientific research institutions show a higher rate of granting. Generally speaking, the seed breeding units now pay more attention to maize variety protection, but the quality of varieties for application shall be further improved; the approving authorities are faced with plenty of needs for high efficiency; there is still some room for the foreign companies to improve their involvement in maize variety protection in China.

Location and Linkage Markers for Candidate Interval of the White Petal Gene in Brassica napus L. by Next Generation Sequencing

Xue CHEN,Rui WANG,FuYu JING,ShengSen ZHANG,LeDong JIA,MouZheng DUAN,Yu WU

Scientia Agricultura Sinica. 2020, 53(6):  1108-1117.  doi:10.3864/j.issn.0578-1752.2020.06.003

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【Objective】 Since the petal colour can be used for ornamental and landscaping purposes, the petal color has been one of the major goals of breeding and genetic research in Brassica napus L.. In this paper, Genetic analysis, candidate interval identification, linkage markers and synteny analysis were applied to elucidate the genetic control of the white petal in Brassica napus L.. 【Method】 To Map the white petal locus, an inbred line Y05, which has yellow flowers, was crossed with an inbred line W01, which has white flowers. The F₁ plants were self-crossed to develop F₂ mapping population. For BSA, parental and two pools with 30 yellow petal lines and 30 white petal lines of F₂ were constructed by mixing an equal amount of DNA or RNA respectively. 30× or 5× depth of genome-sequencing was conducted. Darmor-bzh, Zhongshuang11(ZS11), Darmor and Tapidor as the reference genome were aligned to sequence data from the 2 bulks and parents using QTL-seq workflow. The sliding window method with a window size of 2Mb and a step size of 50kb was used to present the SNP indexes of the whole genome. The difference between the SNP indexes of the two pools was calculated as the delta (SNP- index). Candidate regions for petal color were identified from the chromosomes with 95% confidence intervals. Mutation Mapping Analysis Pipeline for Pooled RNA-seq (MMAPPR) without parental strain information and requiring Darmor-bzh reference genome calculated allelic frequency by Euclidean distance followed by Loess regression analysis, and identified the region where the mutation lies, and generated a list of putative coding region mutations in the linked genomic segment. The SSR primers were designed by using MISA and Prime 3 for repeated sequence identification, and the SSR primers were screened by polyacrylamide gel electrophoresis in the F₂ population. 【Result】 The segregation of white petal and yellow petal among F₂ population fitted the Mendelian segregation ratio of 3:1. This indicates that the white petal trait was controlled by a major gene and that white petal was dominant over yellow petal. The results of the candidate interval using whole-genome re-sequencing showed that a candidate interval (52-55 Mb) exceeding the threshold value was identified for the petal color on chromosome C03 when Darmor-bzh was used as reference genome. While ZS11, Darmor and Tapidor were aligned to sequence data, candidate intervals for white petal were all identified on chromosome C03. Linked region peaks (54-55 Mb) identified by MMAPPR for the petal color was on chromosome C03 of Darmor-bzh. Six SSR markers that were located in the interval (760 kb) were closely linked to the white flower gene. Synteny analysis showed that the interval 760 kb (52.81-53.57 Mb) was corresponding to chromosome A02 (56.76-57.40 Mb) of Brassica rapa and chromosome C03 (10.99-11.28 Mb) of Brassica oleracea. 【Conclusion】 The white petal was controlled by a major gene which was dominant over yellow petal. Six SSR markers closely linked to the white petal gene were selected. A candidate interval for white petal gene was identified on chromosome C03 (52-55 Mb). The present study may facilitate cloning of the white petal gene as well as marker assisted selection.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY

Effects of Photoperiod Changes on Morphological Characters and Young Panicle Development in Proso Millet (Panicum Miliaceum L.)

Ming DONG,YanMiao JIANG,HaiQuan LI,LingLing GENG,JianYe LIU,ZhiHong QIAO,GuoQing LIU

Scientia Agricultura Sinica. 2020, 53(6):  1118-1125.  doi:10.3864/j.issn.0578-1752.2020.06.004

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【Objective】 Proso millet is a typical short-day crop that is extremely sensitive to photoperiod changes which limits the geographical adaptation of proso millet varieties. In the present study, the important agronomic traits have been characterized and young panicle development has been observed under both short-day and long-day conditions, which may help better understand reaction mechanism to photoperiod changes and support widely adaptable va riety breeding in proso millet. 【Method】A landrace “Erzigan” was planted in pots under a 18h day light condition, then transferred to a 12h day light condition after 0 day (CK), 10, 15, 20 and 25 days of seedling emergency, each treatment was replicated three times. The main plant characters including heading time, plant height, stem diameter, panicle length, dry panicle weight and dry grain weight per panicle were measured and young panicle development was observed and photographed by using stereo microscope. 【Result】 Plants grown for 25 days under long-day conditions had a plant height of 115.6 cm and a single panicle grain weight of 0.647 g, which was 109.0% and 472.6% higher than the control, respectively. The dry matter accumulation of stem, leaves and ears increased by 416.7%, 142.9% and 412.0%, respectively, comparing with the control. However, the difference in dry matter weight of each organ between the 25d and 20d treatments was not significant. Under the condition of 18 hours day light, the growing point of the stem tip of the proso millet kept in the unstretched period, which meant the plants were at vegetative growth stage without reproductive growing. After 5 days growing under short-day light conditions, the plants began reproductive growth, and the young panicles started to differentiate. The process of young panicle development could be classified into 7 stages including unstretched stage, growing point elongation stage, ear branch differentiation stage, spikelet differentiation stage, floret differentiation stage, pistil and stamen differentiation stage, and pollen grain formation stage. The whole process of young panicle development could last about 15 days before heading, which was not affected by the prolonged light period treatments at early growing stage. 【Conclusion】Artificially prolonging the light period under short day conditions could extend vegetative growth period and was in favor of dry matter accumulation, which can significantly increase the biomass and yielding of proso millet. Short-day conditions promote the transformation of proso millet from vegetative growth to reproductive growth. The whole process of young panicle development could be classified into seven stages, which could last about 15 days before heading and was not affected by all the five treatments at early growing stage.

Effects of Drought Treatments at Different Growth Stages on Growth and the Activity of Antioxidant Enzymes in Sweetpotato

HaiYan ZHANG,BeiTao XIE,BaoQing WANG,ShunXu DONG,WenXue DUAN,LiMing ZHANG

Scientia Agricultura Sinica. 2020, 53(6):  1126-1139.  doi:10.3864/j.issn.0578-1752.2020.06.005

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【Objective】 The aim of this study was to investigate the mechanism of yield reduction of sweetpotato (Ipomoea batatas (L.) Lam) caused by drought stress at different growth stages, so as to provide theoretical basis and technical support for production of sweetpotato in dryland areas. 【Method】 Field experiments were conducted under a rain exclusion shelter to investigate the effects of drought treatments at different growth stages on growth and the activity of antioxidant enzymes in sweetpotato. Two sweetpotato cultivars (JS 21, a drought-tolerant cultivar, and JZ 1, a drought-sensitive cultivar) were subjected to four drought stress treatments respectively, including WW (well watered during the whole growth period, constructed as a control), DS1 (drought stress during the establishment stage), DS2 (drought stress during the intermediate stage), and DS3 (drought stress during the final stage). 【Result】 Drought stress resulted in significant decrease of dry weight in sweetpotato, and which declined most under the earliest drought stress. Compared with the control, the dry weight of storage roots of DS1, DS2 and DS3 in drought-tolerant cultivar (JS 21) were 32.24%, 30.68% and 13.76%, respectively, while 44.02%, 39.54% and 17.87% in drought-sensitive cultivar (JZ 1), respectively. The activity of antioxidant enzymes of functional leaves, fibrous roots and storage roots increased after drought stress. Similarly, the earlier of the drought stress, the greater influence on the activity of antioxidant enzymes was observed in sweetpotato. The enzyme activity in the fibrous roots in each stage was higher than that in the storage roots and the functional leaves. Our results indicated that the fibrous roots were the most sensitive to drought stress. Drought stress could lead to the increase of the relative electrical conductivity of functional leaves, and the MDA content in functional leaves, fibrous roots and storage roots of sweetpotato. The earlier the application of the drought stress in sweetpotato, the greater the increase of the MDA content was observed. 【Conclusion】 The earlier of the drought stress, the greater influence on the activity of antioxidant enzymes was observed in sweetpotato, and could not be renovated. Therefore, the normal growth of leaves and roots were inhibited, and the formation and bulking of storage roots were limited. Establishment stage of sweetpotato was the most sensitive to drought stress.

Evaluation of Shade Tolerance of Peanut with Different Genotypes and Screening of Identification Indexes

TingHui HU,LiangQiang CHENG,Jun WANG,JianWei LÜ,QingLin RAO

Scientia Agricultura Sinica. 2020, 53(6):  1140-1153.  doi:10.3864/j.issn.0578-1752.2020.06.006

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【Objective】 The main aim of this study was to explore the methods of evaluating shade-tolerance, analyze the shade-tolerance of peanut in different genotypes, screen suitable identification indexes of shade tolerance, and establish an evaluation model of shade tolerance, so as to provide some theoretical support for screening of shade-tolerance resources and variety breeding of peanut. 【Method】 Qiannuo 868 was selected as the corn variety, and under the conditions of corn-peanut intercropping system and net cropping peanut, thirty peanut cultivars (lines) were treated in the field experiment. Net photosynthetic rate (X₁₃), stomatal conductance (X₁₄), intercellular CO₂ concentration (X₁₅) and transpiration rate (X₁₆) of peanut leaves were measured at the pod stage of peanut. The main stem height (X₁), side branch length (X₂), total branch number (X₃), effective branch number (X₄), plant pod number (X₅), mature pods per plant number (X₆) and yield per plant (X₁₁) were measured in the peanut mature stage. The 100-pod weight (X₇), kernel weight of 100 fruiting (X₈), 100-kernel weight (X₉), shelling percentage (X₁₀) and plot yield (X₁₂) were measured after harvesting and drying of peanut seed. 【Result】 The variation range of shade tolerance coefficient of each single index was different in different peanut varieties (lines). The 16 single indicators were converted into 5 independent comprehensive indicators through principal component analysis, and their contribution rates respectively were 33.860%, 26.666%, 11.176%, 8.471% and 6.954%, representing the information of 87.127% of all data. Through membership function, the largest membership function values of comprehensive indexes CI₁-CI₅ respectively were 6-2, Tianfu 29, 201150118A, 201240413 and Minhua 6. The thirty peanut varieties (lines) were divided into 3 categories: the first category was shade tolerance type, including 11 varieties (lines); the second category was moderate shade tolerance type, including 18 varieties (lines); the third category was sensitive type, including 1 variety (line). The optimal mathematical model of peanut shade tolerance evaluation was established, namely D=0.741+0.576X₉+0.507X₁₁+ 0.298X₁₃+0.272X₁₂+0.406X₁₀ (R²=0.990), and its accuracy was higher than 93.18%. Then, 5 indexes for peanut shade tolerance identification were selected: 100-kernel weight, yield per plant, net photosynthetic rate, plot yield and the ratio of shelled. The shade tolerance type peanut had a higher net photosynthetic rate, higher 100-kernel weight, yield per plant, plot yield and shelling percentage, while the sensitive type peanut were the opposite. 【Conclusion】 It was relatively scientific to evaluate and analyze the shade tolerance of peanut by multivariate statistical analysis. 30 peanut varieties (lines) were divided into three categories: shade tolerance type, moderate shade tolerance type, and sensitive type. 100-kernel weight, shelling percentage, yield per plant, plot yield and net photosynthetic rate could be used as the indexes to identify the shade tolerance of peanut. The comprehensive evaluation value of shade tolerance could be calculated to predict peanut shade tolerance by measuring the five indexes under the same conditions.

PLANT PROTECTION

Pathogenicity and Genetic Diversity of Bipolaria maydis in Sanya, Hainan and Huang-Huai-Hai Region

JiaYing CHANG,ShuSen LIU,Jie SHI,Ning GUO,HaiJian ZHANG,HongXia MA,ChunFeng YANG

Scientia Agricultura Sinica. 2020, 53(6):  1154-1165.  doi:10.3864/j.issn.0578-1752.2020.06.007

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【Objective】The objective of this study is to clarify the pathogenicity differences, genetic diversity and relationship among the Bipolaria maydis strains from southern maize breeding base of Sanya, Hainan and Huang-Huai-Hai region, and to provide a theoretical basis for screening resistance of maize varieties under natural disease conditions in the breeding process. It also provides a reference for the popularization and utilization of maize varieties in Huang-Huai-Hai region.【Method】The pathogens were isolated from diseased leaves collected from Sanya, Hainan and Huang-Huai-Hai region, and a total of 61 strains were obtained by identification of morphology and molecular biology. The pathogenicity of 61 strains was identified by an artificial spray inoculation method, and 16 primers with clear, repetitive and polymorphic bands were used for ISSR-PCR. Popgen32 software was used to calculate the genetic distance and genetic similarity among the populations, and NTsys2.10e software was used for cluster analysis and constructing a cluster map of the pathogens in Sanya, Hainan and Huang-Huai-Hai region.【Result】The results of pathogenicity test showed that there was no weak pathogenic strain and 57.1% strong pathogenic strains isolated from Sanya, Hainan, while that of Huang-Huai-Hai region accounted for 47.5% and 17.5%, respectively. The results of genetic diversity analysis showed that the Nei’s gene diversity index (H) was 0.2820 and Shannon’s information index (I) was 0.4197 on the average level of population, indicating that there was a certain genetic variation in the pathogen. The genetic similarity coefficient was 0.9028-0.9618 and the genetic distance was 0.0390-0.1023 among different geographical populations, which indicated that the overall genetic similarity coefficient was relatively high and the genetic distance was close, but there were still different degrees of genetic differentiation among different geographical populations. Among which, the genetic similarity coefficient of strains in Henan and Hebei was the highest (GS=0.9618), and the genetic relationship was the closest; the genetic similarity coefficient of strains in Henan and Sanya was the lowest (GS=0.9028), and the genetic relationship was relatively far. The cluster analysis showed that the strains in Sanya and Huang-Huai-Hai region were obviously divided into two groups when the similarity coefficient was 0.722.【Conclusion】There are some differences in B. maydis pathogenicity between the main maize producing area of Huang-Huai-Hai region and the southern maize breeding base of Sanya, Hainan. The isolation frequency of the strong pathogenic strains in Sanya was higher than that in Huang-Huai-Hai region. The strain populations in Huang-Huai-Hai region and Sanya region have rich genetic diversity, and genetic diversity has a certain relationship with geographical origin. The genetic relationship of the strains in the adjacent regions was relatively close. However, the genetic similarity coefficient of strains between Sanya region and Huang-Huai-Hai region is relatively high, the genetic relationship is close, and also there are some gene exchanges between the two populations. Therefore, selection of resistant maize varieties or resistant parent materials under natural conditions in southern maize breeding base of Sanya has a certain effect on the yearly increase of resistance to southern corn leaf blight in Huang-Huai-Hai region, which is helpful to reduce the occurrence of disease in Huang-Huai-Hai region.

Effects of Glyphosate on Weed Control, Soybean Safety and Weed Occurrence in Transgenic Herbicide-Resistant Soybean

HuiLin YU,Fang JIA,ZongHua QUAN,HaiLan CUI,XiangJu LI

Scientia Agricultura Sinica. 2020, 53(6):  1166-1177.  doi:10.3864/j.issn.0578-1752.2020.06.008

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【Objective】 Transgenic soybean ‘GE-J16’ that co-expressed with GAT and EPSPS conferring resistance to glyphosate, is a herbicide-resistant (HR) variety in China with independent intellectual property. The objective of this study is to evaluate the effect of glyphosate application on weed control, soybean safety, and weed occurrence in glyphosate-resistant (GR) soybean ‘GE-J16’, and to provide the basic data for HR crops’ safety monitoring after commercial planting and weed management strategies.【Method】For weed control, in each soybean plot, 5 sample points were chosen along a diagonal and 0.25 m ²was tagged as one sample point, 28 days after glyphosate application (DAG), the numbers of grassy and broadleaf weeds were surveyed and the above-ground parts were cut to get fresh weight, then weed control efficacy was calculated by fresh weight and weed number. For soybean safety, in each soybean plot, 5 sample points were chosen along a diagonal and 4 soybean plants were tagged with random selection in one sample point. The plant height and compound leaf number were investigated on the day of spraying, 7, 14, 21, and 28 DAG, separately. At the same time, herbicide damage of plants was visually observed. Before harvest, 50 soybean plants were collected from each plot, pod number of each plant and yield of 50 plants were tested. For weed occurrence, in each soybean plot, 5 sampling points were chosen along a diagonal and 0.25 m ²was tagged as one sample point. All selected sampling points were different from those sampling points of weed control. The number and type of each weed species were counted in each sampling point. For each species of weeds, relative abundance (RA) was calculated.【Result】In 2016, at the glyphosate application doses of 900, 1 800 and 3 600 g a.i./hm ², the plant control efficacy of grassy and broadleaf weeds was 84.30%, 95.22%, 83.62%, and 49.80%, 64.52%, 61.93%, respectively. The fresh weight control efficacy of grassy and broadleaf weeds was above 95.36% and 82.05%, respectively. In 2017, at the same glyphosate application doses, the plant control efficacy of grassy and broadleaf weeds was above 94.93% and 85.09%, respectively. The fresh weight control efficacy of grassy and broadleaf weeds was above 98.00% and 96.57%, respectively. Glyphosate did not affect plant growth after application and soybean yield of different glyphosate treatments was higher than that of hand weeding treatment. Two years of short-term experimental research showed that weed species shifted in transgenic GR soybean after glyphosate application. The weed flora was dominated by six species including broadleaf weeds Amaranthus retroflexus, Calystegia hederacea, Portulaca oleracea, and grassy weeds Setaria viridis, Digitaria sanguinalis, and Eleusine indica in GR soybean without weeding, while in GR soybean sprayed with glyphosate at 900 to 3 600 g a.i./hm ², the weed flora was dominated by C. hederacea, Lagopsis supina, P. oleracea, E. indica, and S. viridis.【Conclusion】Glyphosate at 900-3 600 g a.i./hm ² has a good weed control efficacy in transgenic GR soybean ‘GE-J16’, and it is safe for soybean ‘GE-J16’. Thus, transgenic soybean ‘GE-J16’ has great potential for application in China in the future. The weed species shift in GR soybean after glyphosate application, and it will be needed to monitor for a long time if transgenic soybean is permitted to plant in China.

SPECIAL FOCUS: SOIL ACTIVE ORGANIC CARBON

Influencing Factors and Comprehensive Analysis of Soil Active Organic Carbon

ShuXiang ZHANG,WenJu ZHANG,MingGang XU

Scientia Agricultura Sinica. 2020, 53(6):  1178-1179.  doi:10.3864/j.issn.0578-1752.2020.06.009

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The Response of Water-Soluble Organic Carbon to Organic Material Applications in Black Soil

Dan WEI,ShanShan CAI,Yan LI,Liang JIN,Wei WANG,YuMei LI,Yang BAI,Yu HU

Scientia Agricultura Sinica. 2020, 53(6):  1180-1188.  doi:10.3864/j.issn.0578-1752.2020.06.010

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【Objective】The change characteristics of water soluble organic carbon (WSOC) content and components in black soil with the addition of different organic materials were explored to provide a scientific basis for soil fertility improvement methods in black soil area.【Method】This study was based on experimental plots of returning organic materials to the field in Keshan County, Heilongjiang Province, and the experiment has lasted for seven years. The content and structure of WSOC treated with organic fertilizer, biochar, straw and single fertilizer treatment (CK) was analyzed by routine determination and fluorescence analysis.【Result】Compared with the single application of chemical fertilizer, the content of soil water-soluble organic carbon increased by 9.65%-20.30% and soil organic carbon increased by 6.63%-14.86% under the application of organic materials. The contents of tyrosine-like protein and tryptophan-like protein in WSOC decreased under the treatment of organic materials. The application of organic fertilizer increased the contents of metabolites of soluble microorganisms in WSOC, increased the contents of fulvic acid and humic acid in WSOC, and simplified their structures. Straw and biochar simplified the structure of fulvic acids and biochar complicates the structure of humic acids in WSOC.【Conclusion】Organic fertilizer, biochar and straw improved the content of soil water-soluble organic carbon, enhanced the decomposition and metabolism of soil microorganisms, increased the content and simplified the structure of fulvic acid component in water-soluble organic carbon. Organic fertilizer had the best effect.

The Effects of Long-Term Fertilization on the Labile Organic Matter and Carbon Pool Management Index in Different Soil Layers in Red Soil

XiaoLei LI,YuJun ZHANG,FengMin SHEN,GuiYing JIANG,Fang LIU,KaiLou LIU,ShiLiang LIU

Scientia Agricultura Sinica. 2020, 53(6):  1189-1201.  doi:10.3864/j.issn.0578-1752.2020.06.011

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【Objective】This study was aimed to explore the characteristics of the labile organic matter (LOM) and carbon pool management index (CPMI) under different fertilization in different soil layers in red soil, so as to provide a theoretical basis for carbon pool management in red soil. 【Method】Based on the long-term experiment site located at Jinxian, Jiangxi province, four typical treatments were chosen as: (1) no fertilization (CK); (2) mineral nitrogen, phosphorus, potassium (NPK); (3) NPK combined with pig manure and straw (NPKSM); (4) NPK combined with straw (NPKS). The highly LOM (HLOM), moderately LOM (MLOM), lowly LOM (LLOM), non-LOM (NLOM) and CPMI in four soil depths (i.e. 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm) were measured and analyzed. 【Result】The results showed that the soil organic matter (SOM) content under each treatment was decreased with increasing of soil depths. Compared with CK treatment, the SOM was increased under the fertilization treatments. In 0-20 cm, the SOM content was ordered as NPKSM >NPKS >NPK >CK, with the highest value as 43.47 g·kg ^-1(10-20 cm) and 45.09 g·kg ^-1(0-10 cm) under NPKSM treatment. In 20-60 cm, the SOM content under NPKSM and NPKS was significantly higher than that under CK, while there was no different between NPKSM and NPKS. The dissolved organic carbon (DOC) content was decreased with soil depth under all treatments except NPK. The DOC content under NPKSM and NPKS was significantly higher than that under NPK and CK, and the highest value was 35.93 mg·kg ^-1under NPKSM treatment. The HLOM, MLOM, and LLOM content were increased under fertilization treatments compared with CK treatment. The LOM content was ordered as LLOM> MLOM> HLOM under the same treatment in same soil layer. All the LOM components content was significantly higher under NPKSM and NPKS treatments in all soil layers. The HLOM and MLOM content under all treatments were trended as first increased and then decreased with increasing of soil depth. The HLOM content was reached to peak in 20-40 cm under NPKSM (5.31 g·kg ^-1) and NPKS (5.49 g·kg ^-1). The highest MLOM content appeared in 10-20 cm under NPKSM treatment with 10.62 g·kg ^-1. The LLOM content under all treatments was decreased with soil depth. In 0-20 cm, the LLOM content was highest under NPKSM treatment with 18.52 g·kg ^-1(0-10 cm) and 15.93 g·kg ^-1(10-20 cm), respectively. The proportion of different LOM components and CPMI were increased under the fertilizer treatments. In 0-10 cm, compared with CK, the LOM content under NPKS and NPKSM was increased by 27.9%and 29.48%, respectively, MLOM proportion was increased by 7.21% and 7.72%, respectively, HLOM proportion was increased by 5.10% and 4.96%, respectively. The CPMI under fertilization treatment was higher than 100, and which was obviously higher under NPKSM and NPKS. In 0-20 cm, the different LOM components were extremely significantly positive correlation(P≤0.01), and they were significantly positive correlated with total SOM, total nitrogen, dissolved SOM and rice yield (P≤0.05). 【Conclusion】The SOM and LLOM content under all treatments were decreased with the increasing of soil depth. The SOM and all LOM components were significantly improved under NPKSM treatment, and HLOM and CPMI under NPKSM were the highest, followed by NPKS in 0-20 cm, while, which was the highest under NPKS in 20-60 cm.

Effect of No-Tillage with Manure on Soil Enzyme Activities and Soil Active Organic Carbon

FengJun ZHENG,Xue WANG,Jing LI,BiSheng WANG,XiaoJun SONG,MengNi ZHANG,XuePing WU,Shuang LIU,JiLong XI,JianCheng ZHANG,YongShan LI

Scientia Agricultura Sinica. 2020, 53(6):  1202-1213.  doi:10.3864/j.issn.0578-1752.2020.06.012

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【Objective】The purpose of this study was to identify the effect of no-tillage with manure on soil enzyme activities and soil organic carbon content, clarify scientific application of fertilizers under no-tillage system, enhance soil biological activity, and promote soil quality.【Method】Based on the long-term field experiment in Yuncheng, Shanxi, we selected no-tillage (NT) treatment and no-tillage with manure (NTM) to measure soil enzyme activity (β-Glucosidase, β-Xylanase, cellobiohydrolase, and α-1,4-Glucosidase) relating to carbon transformation, soil temperature, soil water content and soil respiration rate in growth stages of winter wheat and soil total organic carbon and soil active organic carbon content (dissolved organic carbon - DOC; Easily oxidized organic carbon - EOC; Microbial biomass carbon -MBC) in productive growth stages of winter wheat.【Result】(1) There were significant seasonal differences in soil enzyme activities among the growth stages of winter wheat. The activities of β-Xylanase and α-1,4-Glucosidase increased in jointing stage and filling stage, while the activity of β-Glucosidase and cellobiohydrolase showed a small fluctuation. The changes of soil respiration at different growth stages were basically consistent with the activities of β-Xylanase and α-1,4-Glucosidase. Besides, the results of principal component analysis showed that the soil enzyme activities were mainly affected by soil water content and soil respiration rate. (2) No-tillage with manure significantly increased β-Xylanase activity at different growth stages (over-wintering stage: 17.6%, heading stage: 8.5%, filling stage: 14.1%, and mature stage: 10.0%). The activity of α-1, 4-Glucosidase increased by 16.7% and 10.2% respectively at the overwintering stage and jointing stage. The results of principal component analysis showed that the enzyme activities were mainly affected by soil temperature and soil respiration rate. (3) No-tillage with manure significantly increased the content of TOC, DOC, EOC and MBC in winter wheat growing season (TOC: 16.9%, DOC: 27.7%, EOC: 38.4% and MBC: 50.7%). (4) The correlation analysis of soil biological indicators were higher between β-Xylanase, α-1, 4-Glucosidase activities and total organic carbon, organic carbon active components in winter wheat growth stages (correlation index were greater than 0.85).【Conclusion】No-tillage with manure increased β-Xylanase and α-1,4-Glucosidase activities by influencing soil water content and soil temperature. Meanwhile, the addition of manure increased the content of total organic carbon and active organic carbon components on the basis of straw returning to the field, which was beneficial to the improvement in biological activities such as soil enzyme and soil quality.

Effects of Long-Term Fertilization on the Stability of Black Soil Water Stable Aggregates and the Distribution of Organic Carbon

XiuZhi ZHANG,Qiang LI,HongJun GAO,Chang PENG,Ping ZHU,Qiang GAO

Scientia Agricultura Sinica. 2020, 53(6):  1214-1223.  doi:10.3864/j.issn.0578-1752.2020.06.013

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【Objective】Based on the long-term fertilization experiment station, in aims to study the influences on the soil fertility by long-term application of chemical fertilizer and manure, the characteristics of water stable aggregates and structure of organic carbon was analyzed under different fertilizer application conditions.【Method】0-20 cm soil samples were collected from the 37-year long-term field experiment, including six treatments: CK (no fertilizer), NPK (chemical fertilizer alone), M₂ (normal manure application), M₂NPK (the chemical fertilizer combined with normal manure rate), M₄ (high quantity manure application), and M₄NPK (the chemical fertilizer combined with high quantity manure rate). Stability of water stable aggregates and distribution of organic carbon in aggregates were analyzed by wet sieve method.【Result】The proportion of large aggregates was reduced,while the proportion of micro aggregates was increased significantly under long-term application of organic and chemical fertilizer and high amount of organic fertilizer conditions. There was not significant change for the distribution of aggregates under long-term application of chemical fertilizer and constant organic fertilizer conditions. Compared with CK, the proportions in macro-aggregate of M₂NPK, M₄NPK and M₄ were reduced by 32.7%, 45.8% and 55.4%, respectively, and the proportion of that in micro-aggregate were increased by 73.2%, 102.5% and 123.9%, respectively. The stability of surface soil water stable aggregates was reduced significantly under long-term organic combined chemical fertilizer and high amount of organic fertilizer conditions. The soil organic carbon content was increased significantly by 1.12-2.06 times as much as CK under long-term fertilization condition, and the increase of organic carbon content was more significantly in organic fertilizer and organic combined with chemical fertilizer. The content of organic carbon in soil water stable aggregates of each size was increased under long-term organic fertilizer application, while the increase of organic carbon content in each treatment was gradually decreased with the decrease of particle size. Organic carbon content in the water stable macro-aggregate was significantly higher than that in the micro-aggregate, indicating that the organic carbon was mainly distributed in the macro-aggregate. The contribution rate of organic carbon in macro-aggregate was reduced significantly, and the contribution rate of organic carbon was increased significantly in micro-aggregate under long-term application of high amount of organic and combined with chemical fertilizer. The contribution rate of organic carbon in other treatments was higher in macro-aggregates than in micro-aggregates.【Conclusion】There were no significant effect for distribution and organic carbon content in aggregates under long-term chemical fertilization. The proportion of macro-aggregates and the stability of soil aggregates were reduced significantly under high amount of organic fertilizer and combination of organic and chemical fertilizer. The content of organic carbon in the aggregates was increased significantly under long-term application of organic fertilizer. The contribution rate of organic carbon in macro-aggregates was reduced significantly under high amount of organic fertilizer and combined with chemical fertilizer. The micro-aggregate was the dominant aggregate size of the organic carbon contribution rate.

A Meta-Analysis of Long-Term Fertilization Impact on Soil Dissolved Organic Carbon and Nitrogen Across Chinese Cropland

YaLin LI,XuBo ZHANG,FengLing REN,Nan SUN,Meng XU,MingGang XU

Scientia Agricultura Sinica. 2020, 53(6):  1224-1233.  doi:10.3864/j.issn.0578-1752.2020.06.014

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【Objective】The objectives of this study were to assess the in?uence of long-term fertilization on the soil dissolved organic carbon (DOC) as well as soil dissolved organic nitrogen (DON) under various use types, cropping systems and soil pH, to give management guidance on how to increase soil carbon and nitrogen in Chinese Cropland. 【Method】In current study, 72 literatures including effects of long-term fertilization on the contents of DOC and DON in Chinese Cropland from 2000 to 2019 were selected (510 dataset for DOC and 208 dataset for DON). The meta-analysis was used to investigate how the magnitude of the DOC and DON contents response to mineral fertilizer and manure application at three aspects: use types, cropping systems and soil pH.【Result】At national scale, the contents of DOC and DON in the fertilized soils were significantly higher than those in the no fertilized soils (CK). The increments of DOC and DON contents in manure applied soils (60%和93%) were 4.6 and 3.2 times higher than those in the soils with mineral fertilizers (13% and 29%). Under different use types, fertilizer application can significantly increase the contents of DOC and DON in upland soil, and the increments of DOC and DON contents improved by manure in upland soil were higher than those in upland-paddy soil. Furthermore, manure application could increase the content of DOC in mono-cropping (85%) compared with no fertilizer (CK), which was significantly higher than that in double-cropping (38%). For the alkaline soils (pH>7.5), the increments of DOC and DON contents in the treatment with manure amendment (85% and 162%) were higher than those in the neutral (6.5＜pH＜7.5, 48% and 70%) and acidic soils (pH＜6.5, 32% and 61%) compared with no fertilizer (CK), respectively. 【Conclusion】In summary, the application of manure (only manure or combined with mineral fertilizer) could significantly increase the contents of DOC and DON, but the effects varied greatly across various use types, cropping systems, soil pH. Therefore, the appropriate conditions of soil and environment should be taken into account when applying manure.

HORTICULTURE

Selected Related Genes about Incompatibility of Distant Hybridization in Paeonia by iTRAQ Analysis and Transcriptome

Dan HE,DongBo XIE,JiaoRui ZHANG,SongLin HE,ChaoMei LI,YunBing ZHENG,Zheng WANG,YiPing LIU,Yan LI,JiuXing LU

Scientia Agricultura Sinica. 2020, 53(6):  1234-1246.  doi:10.3864/j.issn.0578-1752.2020.06.015

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【Objective】Distant hybrid breeding is the main method of cultivar improvement and breeding in tree peony and herbaceous peony, while cross-incompatibility is an important restriction for breeding rapid development. Based on the previous researches, the analysis on different protein of stigma in pollen-stigma interaction and transcriptome was further explored. The mechanism of cross-incompatibility between tree peony and herbaceous peony was revealed, so as to provide the theoretical support for hybridized breeding.【Method】The stigmas of combinations Paeonia lactiflora ‘Fenyunu’ × P. lactiflora ‘Fenyunu’ and P. lactiflora ‘Fenyunu’ × P. ostii ‘Fengdanbai’ were harvested at 24 h after pollination, which were used as materials for isobaric tags and analysis for relative and absolute quantitation (iTRAQ) and transcriptome, respectively. Bioinformatics was analyzed on the data of protein and transcriptome. Quantitative Real-time PCR (qRT-PCR) technique was used to validate the expression data of selected differentially expressed genes (DEGs). 【Result】iTRAQ was used to analyze DEPs of stigma of distant hybrid between tree peony and herbaceous peony, and the result showed that 685 DEPs were belonged to 188 pathways, in which 18 pathways were significantly enriched. There were four pathways with obvious difference in protein, including RNA degradation, mitogen-activated protein kinase (MAPK) signaling pathway, calcium signaling pathway, and phosphatidylinositol signaling system. In RNA degradation pathway, enolase, DnaK (HSP70), and GroEL (HSP60) were all down-regulated. In calcium signaling pathway, calmodulin (CALM) was down-regulated, while adenine nucleotide translocase (ANT) was up-regulated. In MAPK signaling pathway, Glyoxalase (GloI) was down-regulated. In phosphatidylinositol signaling system, CALM was also down-regulated. 6 genes were selected randomly to confirmed their expression by qRT- PCR, and the result showed that the expression profiles of the selected genes was in agreement with the results from protein analysis, and they were all down-regulated. A total of 52 998 annotated Unigenes were obtained by transcriptome sequencing, accounting for 40.37% of all Unigenes. Based on the RPKM (Reads Per Kilobase per Million) of six samples, 16 224 DEGs were obtained, among which13 61 were up-regulated, and 2 863 were down-regulated. Based on pathway enrichment analysis of DEGs, it indicated that the level of enrichment of DEGs in “Oxidative phosphorylation”, “ABC transporters” and “Biosynthesis of secondary metabolites” pathways were more significant and reliable than that of selfing. The genes related with incompatibility of distant hybridization were CalS-5, CalS-12 (Callose enzyme), and SPL, which were up regulating expression, but ABCF that was down regulating expression. 【Conclusion】In the data of transcriptome and protein, 6 proteins and 4 genes were closely related to incompatibility of distant hybridization. These proteins and genes might play an important role in incompatibility of distant hybridization.

FOOD SCIENCE AND ENGINEERING

Wheat Gluten, Gliadins and Glutenin Content Changes During Germination Based on the Methods of R5 ELISA and RP-HPLC

HuiMin HU,XueFeng PAN,Heng YANG,Chen CHEN,YinJi CHEN

Scientia Agricultura Sinica. 2020, 53(6):  1247-1255.  doi:10.3864/j.issn.0578-1752.2020.06.016

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【Objective】 The current study was conducted to determine the dynamic changes of gluten, gliadins and glutenin contents in different germination states of wheat, so as to provide a scientific basis for the development of gluten-free food and utilization of germinated wheat. 【Method】Seven wheat grains with different germination states were obtained by controlling the germination conditions. Changes of composition of gliadins and glutenin were analyzed by sodium dedecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and changes of gluten, gliadins and glutenin subunits during wheat germination were further determined by enzyme-linked immunosorbent assay based on R5 antibody (R5 ELISA) and reversed-phase high-performance liquid chromatography (RP-HPLC). 【Result】The content of gluten, gliadins and glutenin subunits in wheat could be determined by R5 ELISA and RP-HPLC. Germination treatment had different effects on the allergic proteins and subunits mentioned above. The content of gluten changed little at the early stage of germination, but decreased significantly at the later stage. The relative content of ω-gliadins did not change significantly. During the germination process, the relative content of α-/β-gliadins was significantly reduced, with the percentage of untreated wheat seeds decreased from 41.85% to 31.51%-35.35% after germination (P＜0.01). The relative content of γ-gliadins increased significantly from 31.37% to 36.69%-39.02% after germination (P＜0.05). The relative content changes of high molecular weight glutenin subunit (HMW-GS) and low molecular weight glutenin subunit (LMW-GS) were not significant. HMW-GS decreased slightly from 8.66% (untreated group) to 5.94% (1/4 bud length) and then to 7.28% (bud length=grain length). LMW-GS increased slightly from 8.30% (untreated group) to 10.45% (bud length=grain length).【Conclusion】Both of the methods R5 ELISA and RP-HPLC could be used for quantitative analysis of wheat sensitized proteins. The content of allergenic protein in wheat decreased during germination. In particular, when the germinating bud was up to 1/2 long, the α-/β-gliadin which containing the most sensitive peptide decreased significantly. It was suggested that moderate germination treatment could reduce sensitization of wheat.

Effect of Pre-Enzymatic-Drum Drying Process on the Quality of Whole Wheat Flakes

Ke YU,Lei LIU,RuiFen ZHANG,JianWei CHI,XuChao JIA,MingWei ZHANG

Scientia Agricultura Sinica. 2020, 53(6):  1256-1268.  doi:10.3864/j.issn.0578-1752.2020.06.017

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【Objective】 The purpose of this study was to explore the effect of pre-enzymatic-drum drying treatment on the quality characteristics of whole wheat groats, which provided a theoretical basis for the processing of high-quality whole wheat groats.【Method】The whole wheat flour was used as raw material, and α-amylase, cellulase and its complex enzyme were used for pre-enzymatic-drum drying to prepare whole wheat flakes: drum-dried whole wheat groats (DWG), drum-dried whole wheat cereal Groats with α-Amylase (DWGA), drum-dried whole wheat groats with cellulase (DWGC), and drum-dried whole wheat groats with α-Amylase and cellulase (DWGAC). The fine wheat flakes were prepared by direct drum drying, namely drum-dried refined wheat Groats (DRG). And then, the flake indexes were determined, such as its rehydration rate, agglomeration rate, water solubility index, water absorption index, gelatinization degree, viscosity, color, starch, reducing sugar, phytic acid content and starch and protein digestion characteristics, to compare and analyze the effect of pre-enzymatic-drum drying process on the quality characteristics of whole wheat flakes. 【Result】 The pre-enzymatic-drum drying treatment could significantly improve the brewing properties of whole wheat groats. Among them, DWG sample had the lowest rehydration rate and the DWGAC rehydration rate was the highest. Compared with the control sample DWG, the agglomeration rates of DWGA, DWGC and DWGAC were significantly reduced, respectively. Pre-enzymatic-drum drying treatment significantly improved the solubility of whole wheat groats, with DWGA, DWGC, and DWGAC increasing by 4.98, 2.07, and 5.04 times, respectively, compared to DWG water solubility index. Meanwhile, pre-enzymatic-drum drying treatment significantly reduced the starch and phytic acid content of whole wheat groats (P＜0.05), while the reducing sugar content and gelatinization degree increased significantly (P＜0.05), and the color of the whole wheat flakes was appropriately reduced. In addition, pre-enzymatic-drum drying treatment significantly increased the proportion of fast-digesting starch in whole-grain tablets, and the content of fast-digesting starch were increased by 22.34%, 34.84% and 46.59%, respectively. Among them, DWGAC had the highest fast-digesting starch content; the in vitro digestibility of the protein were increased by 0.33, 0.25, and 0.26 times, respectively, so the digestibility increased.【Conclusion】The pre-enzymatic-drum drying treatment not only improved the dispersibility of whole wheat groats and reduced the agglomeration rate and viscosity, but also improved the in vitro digestion performance of starch and protein, which enhancing the quality of whole wheat groats.

ANIMAL SCIENCE·VETERINARY SCIENCE·RESOURCE INSECT

The Relationship Between Nutrients and Biological Yield of Different Varieties of Alfalfa

ZeMin LI,Chen ZHANG,ChongYu ZHANG,GuiGuo ZHANG

Scientia Agricultura Sinica. 2020, 53(6):  1269-1277.  doi:10.3864/j.issn.0578-1752.2020.06.018

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【Objective】To determine the content and the variation degree of nutritive and the relationship between the content of various fiber components in different alfalfa varieties. Compare the biological yields of different alfalfa varieties.【Method】Two experiments were conducted. In Experiment 1, selected 16 alfalfa varieties including WL343HQ, WL353HQ, WL354HQ, WL363HQ, WL366HQ, Algonuin, Golden empress, Zhongmu No.3, Zhongmu No.6, Luduo, Luhuang No. 1, Wudi, Lufeng No. 1, Baoding, Zhongyuan804, Aohan and planted on October 2, 2016. Each variety was set up twice and randomly arranged plots. The planting area of each alfalfa variety was 18 m ² (3 m×6 m) , row spacing was 30 cm, and 10 rows were sown. Harvested at the beginning of flowering on May 23, 2018 and determined the biological yield. In experiment 2,prepared 32 samples and determined the content of nutrients such as crude ash (ASH), crude protein (CP), crude fat (EE), crude fiber (CF),neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (ADL) in the dry matter (DM). 【Result】 The results showed that: (1) In alfalfa DM of different varieties, the contents of ASH, NDF, ADF, HCEL, CEL and ADL were significantly different (P<0.01), but the difference of EE content was not significantly (P=0.527). The ASH content of WL363HQ alfalfa was the highest, which was 8.53%. The highest CP content of golden empress alfalfa was 27.19%. The content of EE and CF in baoding 804 alfalfa was the highest, which were 3.01% and 36.69%, respectively. The content of NDF, ADF, CEL and ADL in zhongyuan 804 alfalfa was the highest, which were 57.02%, 42.73, 34.43% and 7.92% respectively. The average values of ASH, CP, EE, CF, NDF, ADF, ADL, CEL and HCEL in alfalfa DM of different varieties were 7.83%, 21.58%, 2.51%, 33.25%, 50.12%, 36.76%, 6.98%, 29.43% and 13.36%, respectively; The coefficient of variation (CV) is between 5.16% and 12.06%. (2) There was a strong correlation between ADF and CEL, ADL content in alfalfa, and the correlation coefficients were 0.9756, 0.9955 and 0.9455. The correlation coefficients between CF and ADF, CEL, ADL content were 0.9114, 0.8849 and 0.9375, respectively. The correlation coefficient between CF (including AIA) and CF was 0.9997. The correlation coefficients between NDF and CEL, ADL, HCEL content were 0.9671, 0.9396 and 0.8736, respectively. The correlation coefficient between ADL (including AIA) and ADL was 0.9989. The correlation coefficients between RFA and ADF, CEL were 0.9826 and 0.9700. (3) There was a strong correlation between relative feeding value (RFV) and NDF content (r=0.9938), which can be used for the estimation of alfalfa RFV: RFV=287.0677-3.4709 NDF (%) n=16 P<0.01. (4) The yields of different alfalfa varieties were different. Baoding alfalfa has the highest yield of crude fat, carbohydrate, hemiculose and cellulose, which were respectively 393.59, 9 308.22, 1 976.32 and 4 208.05 kg·hm ^-2; The yield of golden empress's crude protein was the highest, which was 2 697.23 kg·hm ^-2, and the yield of Baoding's digestible energy (DE) was the highest, which was 126 814.45 MJ·hm ^-2. 【Conclusion】There was a strong correlation between the content of different alfalfa fiber components, and the RFV value of alfalfa was strongly correlated with the NDF component; The yields of different alfalfa varieties are different.

The Zoonotic Bacterium-Helicobacter suis and Its Research Progress

GuangZhi ZHANG,MingYan WANG,Yi LUO,ShiHang XU,ShunDong HE,ShangJin CUI

Scientia Agricultura Sinica. 2020, 53(6):  1278-1286.  doi:10.3864/j.issn.0578-1752.2020.06.019

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Helicobacter suis (H. suis), a Gram negative bacterium, has a typical spiral-shaped morphology and it is highly motile by means of 4-10 flagella at both ends of the cells. H. suis is a vital zoonotic pathogen, and is identified and only recently isolated successfully in vitro by Belgian scientists. Different from H. pylori which mainly colonizes the human stomach, H. suis colonizes the majority of the porcine stomach, and infection rate in pigs at slaughter age can reach 60%-95%, causing gastritis, gastric disorders and decreased weight gain. More importantly, H. suis also infects a minority of human, leading to diverse gastric disorders, gastric diseases even gastric cancer (Mucosa-associated lymphoid tissue lymphoma). Although vigorous innate and adaptive immune response in hosts are induced by H. suis infection, H. suis has evolved series of virulence factors to evade the host immune surveillance to persistently colonize the host stomach, resulting in disruption of gastric homeostasis, induction of chronic inflammation and gastric cancer. Currently scientists are not aware of the transmission route of this bacterium, and pork and related products, saliva and faeces are the most possible carriers for transmission. Pigs, mice and Mongolian gerbils are common animal models to study the pathogenesis of H. suis infection. Although H. suis has substantial effects on porcine health, production performance and welfare as well as human health, there is very limited research on H. suis in China due to the difficulties in bacterial isolation and culture, and research on H. suis in China mainly focus on bacterial detection in clinical samples. H. suis needs microaerobic conditions (85%N₂,10%CO₂ and 5%O₂) for in vitro culture. So far there is very limited information about the pathogenesis of H. suis infection in hosts. Through analyses with H. suis genome and known discoveries, it can be speculated that H. suis may interfere with or evade host defense responses via several mechanisms: high mobility of flagella and acid neutralization, considerable adhesion ability to the gastric epithelial surface, detoxification ability of oxidative stress,induction of cell death and of immune regulation. Combined with the authors’ several years’ research experience in H. suis and available literature, this review summaries and extensively discusses several aspects of H. suis in terms of research history, bacterial features and culture conditions, prevalence status, pathogenesis and current research progress in China and abroad, aiming at enhancing our understanding of H. suis and its pathogenicity as well as providing reference and directions for the future prevention and control of this bacterium.