Acta Agriculturae Zhejiangensis

Genetic diversity in hulless barley by retrotransposons-based markers and simple sequence repeat (SSR) markers

WANG Guorong, HUA Wei, CHEN Gonghai, LONG Zhoukai, LI Bo, ZHANG Wenying, XU Yanhao

2018, 30(3): 357-365. DOI: 10.3969/j.issn.1004-1524.2018.03.01

Abstract ( 776 )

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To evaluate the genetic structure of hulless barley, retrotransposons-based markers (retrotransposon-microsatellite amplified polymorphism, REMAP; inter-retrotransposon amplified polymorphism, IRAP) and simple sequence repeat (SSR) markers were used to obtain the genetic data of 63 hulless barley materials. The IRAP, REMAP and SSR markers detected 315, 143 and 38 alleles, ranged from 9-58, 7-25, and 2-4, with an average of 24.23, 14.30, 2.38 alleles per marker, respectively. The contribution rate of single retrotransposons-based marker polymorphic site was higher than that of SSR marker. As revealed by retrotransposons-based markers, the genetic similarity (GS) among these 63 accessions was from 0.452 to 0.937, with the average of 0.674. The accessions were divided into two subgroups at the GS level of 0.620, which contained 20 and 43 materials, respectively. As revealed by SSR markers, GS among these 63 accessions was from 0.351 to 0.973, with the average of 0.716. The accessions were divided into two subgroups at the GS level of 0.620, which contained 2 and 61 materials, respectively. The wild hulless barley accessions was clustered into a small category by the retrotransposons-based markers at the GS level of 0.740. However, it was unable to distinguish the wild hulless barley from the cultured by SSR markers in the present study. The population structure revealed by retrotransposons-based markers was consistent with the principal coordinate analysis and genetic similarity analysis. However, the population structure revealed by SSR markers showed difference. It was shown that most of the accessions were with single genetic components. The retrotransposons-based markers had advantage in the identification of the relationship of hulless barleys. And more genetic information could be explored by combining the retrotransposons-based markers and SSR markers.

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Prevalence and multilocus gene sequence analysis of Giardia duodenalis in captive non-human primates in parts of Southwest China

TIAN Yinan, WEI Bin, LI Ping, HUANG Xiangming, LI Wei, TU Rui, DAN Jiaming, YUAN Li, YANG Tingyu, PENG Guangneng, ZHONG Zhijun

2018, 30(3): 366-370. DOI: 10.3969/j.issn.1004-1524.2018.03.02

Abstract ( 425 )

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To understand the prevalence and molecular characteristics of Giardia duodenalis in captive non-human primates (NHPs) in parts of Southwest China, a total of 207 fresh fecal samples from rhesus macaques, northern white-cheeked gibbons, golden snub-nosed monkeys and crab-eating macaques were obtained from zoos, farms and laboratory in Southwest China. The oocysts in samples were collected by the Sheather's sucrose flotation technique, and their DNA was extracted. These DNA samples were used to amplify β-giardin (bg), tpi and gdh genes by nest PCR for detecting Giardia. The results showed that 7.73% (16/207) of samples were positive for G. duodenalis infection, and 16 positive samples from rhesus macaques, northern white-cheeked gibbons and crab-eating macaques were identified as assemblage B. Northern white-cheeked gibbons had the highest infection rate (38.89%), and the difference in infection rates among the species was significant (P<0.01). All the positive samples were successfully amplified based on bg, tpi and gdh genes, multilocus genotyping showed the high genetic diversity of bg and tpi. Based on a phylogenetic analysis, potentially zoonotic genotypes of Giardia duodenalis were identified in NHPs in southwest China.

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Isolation and identification of Elizabethkingia meningoseptica from Chinese spiny frog (Quasipaa spinosa) and pathological lesions of its infection

LEI Xueping, GENG Yi, YU Zehui, ZHENG Liping, CAO Shiqi, HUANG Xiaoli, CHEN Defang, OUYANG Ping, LIU Kairui

2018, 30(3): 371-377. DOI: 10.3969/j.issn.1004-1524.2018.03.03

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In April 2016, a serious infectious disease characterized by cataract, cutaneous ulcer and neurological symptoms emerged in a Quasipaa spinosa farm in Ya'an, Sichuan Province. In order to explore the etiology, the pathogen isolation, artificial infection, physical and chemical characteristics of isolated bacteria and sequence analysis of 16S rDNA gene were analyzed. The results showed that a Gram-negative, short rod-shaped bacillus (CM160701) was isolated from the diseased frogs. Healthy Chinese spiny frogs injected the isolate intraperitoneally exhibited the similar clinical signs, gross and histopathological lesions to the naturally infected frogs, and the LD₅₀ value of the isolate was 1.19×10⁶ cfu per frog. The isolated strain was identified to be Elizabethkingia meningoseptica according to physicochemical properties and the 16S rDNA gene sequence analysis. The strain was sensitive to florfenicol, but resistant to enrofloxacin, amoxicillin, doxycycline and so on. Histopathological observation found that the E. meningoseptica infection in Quasipaa spinosa could cause pathological damages to multiple organs which showed degeneration, necrosis and inflammation significantly, especially in the brain, liver, spleen, heart and kidney. This study confirmed E. meningoseptica was the pathogen of the epidemic, and the E. meningoseptica infection could cause Quasipaa spinosa multi-system injuries and lead to death.

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H-FABP gene cloning, SNPs screening and bioinformatics analysis in Gansu black pig

NONG Weilun, BI Yingjie, LI Hongxu, ZHANG Li

2018, 30(3): 378-385. DOI: 10.3969/j.issn.1004-1524.2018.03.04

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This study uses bioinformatics method to analyze the function and property of H-FABP gene encoding protein of Gansu black pig. DNA pooling and direct sequencing techniques were used for SNPs rapid screening and the function prediction of H-FABP protein of Gansu black pig. The results showed that the CDS region of H-FABP gene in Gansu black pig was 402 bp, encoding 133 amino residues, 4 SNPs in CDS region including C⁷³⁴T-Intron1, T¹⁵²C-Exon2,G³⁰A-Intron2 and T¹²¹G-Intron2. Among them, T¹⁵²C-Exon2 was a missense mutation, and the amino acids were converted from threonine (Ile) to threonine (Thr). The bioinformatics prediction showed that H-FABP protein of Gansu black pig was a stable hydrophilic protein, and the secondary structure and tertiary structure were mixed protein mainly with β-fold.

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Effects of phosphorus fertilizing on growth and root morphology of Salvia splendens var. Chengxiang Gongzhu

TONG Jing, LI Suyan, SUN Xiangyang, LIU Kefeng, WANG Hongwei, YANG Meiyan

2018, 30(3): 386-392. DOI: 10.3969/j.issn.1004-1524.2018.03.05

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Salvia splendens var. Chengxiang Gongzhu was supposed as typical garden plant, different phosphorus nutrition solution levels were employed to study their effects on the growth and root morphology of the plants. Six phosphorus concentration levels of 0, 15, 30, 60, 90 and 120 mg·L^-1(named as P₀, P₁, P₂, P₃, P₄, P₅) were applied respectively. The results showed that with the increase of phosphorus application, plant height, crown diameter, ground diameter, leaf area, shoot and root dry weight, total root volume, and root average diameter firstly significantly increased and then dropped, which all reached a maximum in P₂ treatment. Chlorophyll a content and total chlorophyll content reached the highest in P₁ treatment, and showed significant difference compared with other treatments (P<0.05). As the concentration of P increased, total root length reached the maximum in P₅ treatment. The growth index, chlorophyll content and root characteristics in P₀ treatment were all the smallest, indicating the developmental delay. Based on this study, P concentration between 15-30 mg·L^-1 would be most suitable for the Salvia splendens var. Chengxiang Gongzhu.

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Inversion estimation of carotenoid content of dicotyledonous plant leaves based on hyperspectral data

YU Changle, XU Tongyu, WANG Yang, YU Fenghua

2018, 30(3): 393-398. DOI: 10.3969/j.issn.1004-1524.2018.03.06

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Carotenoid (Car) is one of the main pigment of photosynthesis for plants. It plays an important role in light absorption and transmission, chlorophyll protection, leaf senescence delaying and so on. Based on LOPEX’93 database, the present study systematically analyzed quantitative relationship within Car content in dicotyledonous plants leaves and normalized difference vegetation index (NDVI), ratio of vegetation index (RVI), and difference vegetation index (DVI). It was shown that NDVI_{(809, 756)} and RVI_{(809, 756)} combining of infrared band at 756 nm and the near infrared band at 809 nm, and DVI_{(809, 750)} combining of infrared band at 750 nm and 809 nm all could achieve better inversion of Car content. Determination coefficient (R²) of the established regression prediction modes were higher than 0.74. By verifying the accuracy of the inversion model estimated based on vegetation index, it was found that the effects of NDVI _{(809, 756)} and RVI _{(809, 756)} were comparable and better than that of the DVI _{(809, 750)}, of which the prediction accuracies were 0.735 and 0.738, respectively, the root mean square errors were 1.426 1 and 1.420 5, respectively, and the average relative errors were 13.66% and 13.60%, respectively. Thus, estimation of Car content in dicotyledonous plants leaves based on the hyperspectral data was feasible.

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Cloning and expression analysis of phytoene synthase gene from peach fruit

LIANG Minhua, YANG Zhenfeng, SU Xinguo, SONG Chunbo

2018, 30(3): 399-405. DOI: 10.3969/j.issn.1004-1524.2018.03.07

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Full-length cDNAs of phytoene synthase (PSY) was isolated from peach fruits using gene cloning method. PpPSY was 1 532 bp in full length and encoded a predicted protein of 208 amino acids (ORF length 627 bp). Phylogenetic analysis indicated that PpPSY was similar to PSY from Prunus mume. Deduced amino acid sequence demonstrated that PpPSY protein contained substrate binding pocket, substrate-Mg²⁺ binding site, active site lid residues, catalytic residues and aspartate-rich region, which belonged to the isoprenoid biosynthesis enzymes Class 1 superfamily. The quantitative real-time PCR showed that expression level of PpPSY gene in developmental tissues of yellow flesh variety Jinli was higher than that of white flesh variety Hujing, and the expression of PpPSY gene in flower bud, hardcore fruit was significantly higher than that in flower, sprout and softcore fruit. For the cloning and expression analysis of PpPSY from peach fruits was reported, it lays the foundation for further research of carotenoid biosynthetic pathway.

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Identification of Clover yellow vein virus infecting broad bean in China by deep sequencing and characterization of virus-derived small interfering RNAs

ZHANG Chenhua, ZHENG Hongying, YAN Dankan, HAN Kelei, PENG Jiejun, LU Yuwen, LIN Lin, ZHANG Dongfang, CHEN Jianping, YAN Fei

2018, 30(3): 406-412. DOI: 10.3969/j.issn.1004-1524.2018.03.08

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The broad bean samples causing prominent mosaic on leaves were collected in Hefei City, Anhui Province in China, and viruses in samples were detected by deep sequencing. The results showed that Clover yellow vein virus(ClYVV) existed in the broad bean samples and the complete genome ClYVV-HF was obtained by direct sequencing of the amplified genomic region, subsequently. The ClYVV genome of China consists of 9 585 nucleotides excluding the poly(A) tail, the full nucleotide sequence of ClYVV-HF shared a nucleotide identity of 95.45% and 95.10% with that of isolates from Japan(AB011819, NC_003536) and an isolate from Korea (KF975894) reported previously. Characterization of ClYVV-derived small interfering RNAs was further analyzed. The prevalent vsiRNAs size was 21-22 nt, and the 5'-terminal base of vsiRNAs was biased towards A/U. The ClYVV-derived small interfering RNAs were most derived from its genomic-strand RNAs, among the 7 hot spots across the genome, 5 hot spots were predominated by 21 nt vsiRNAs. Biological experiments showed that ClYVV could be used to frictionally inoculate many leguminous crops through juice. This is the first report about the full nucleotide sequence of ClYVV isolate from China.

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Effect of planting density, fertilizer level of nitrogen and boron on yield of purple pepper Fengziyun No.1

SUI Yihu, HU Nengbing, TANG Jinbao

2018, 30(3): 413-419. DOI: 10.3969/j.issn.1004-1524.2018.03.09

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In order to optimize the main cultivation factors that affect the production of pepper crops, the method of three-factor five-level quadratic orthogonal rotation design was used to study the effects of different density (x₁), nitrogen fertilizer level (x₂) and boron fertilizer level (x₃) on the yield of purple pepper Fengziyun No. 1. The results showed that under the experimental conditions, the linear effect of the three factors on the yield of pepper was positive and very significant, and x₂ had the greatest impact on production, followed by x₃, and x₁ had the least impact. The effect of the quadratic term was negative, and x12 had the greatest impact on production, followed by x32, and x22 had the least impact. The interaction effect of x₁x₃ was very significantly positive, the marginal effect of x₁ was the largest. When the planting density was 4 123 plants per 667m², the nitrogen fertilizer was 40.020 kg per 667m² and the boron fertilizer was 1.000 kg per 667m², the fresh pepper fruit weight was the highest of 3 206.678 kg per 667m². The results of comprehensive factor analysis showed the optimized factor combination of high yield of Fengziyun No. 1 with a yield of more than 2 500 kg per 667m² at 95% confidence was that density 3 903-4 172 plants per 667m², nitrogen fertilizer 31.186-36.081 kg per 667m², boron fertilizer 0.724-0.880 kg per 667m².

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Toxicities of eight insecticides against Tetranychus cinnabarinus and their acute toxicities to Bombyx mori

XIE Daoyan, YANG Zhenguo, CHAI Jianping, ZHOU Chuntao, LUO Yanjie

2018, 30(3): 420-425. DOI: 10.3969/j.issn.1004-1524.2018.03.10

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In the present study, in-door toxicities of eight insecticides including rotenone, azadirachtin, matrine, celangulin, veratridine, spinetoram, SYP-9080, pyriproxyfen against Tetranychus cinnabarinus were measured via spraying on the Potter spray tower, and the acute toxicities of these insecticides to 3^rd instar of silkworm were exuviated by food intake poisonous leaf method. The results indicated that the acaricidal activities of azadirachtin, matrine, rotenone, celangulin, veratridine against T. cinnabarinus adults were higher than the other insecticides, and the according median lethal concentrations (LC₅₀) were 0.213, 0.659, 1.621, 13.014, 16.548 mg·L^-1, respectively. The ovicidal activities of celangulin, azadirachtin, veratridine, rotenone and matrine against T. cinnabarinus eggs were higher than the other insecticides, and the according LC₅₀ were 0.254, 3.497, 13.564, 21.936, 35.030 mg·L^-1, respectively. The 3^rd instar larvae of silkworm showed spit, antifeedant, body shrinkage and other symptoms of poisoning 48 h after eating mulberry leaves containing the above eight insecticides. Among these pesticides, except that pyriproxyfen was moderately toxic, the remaining pesticides to silkworms were highly toxic or hypertoxic. Therefore, azadirachtin, celangulin, veratridine, rotenone and matrine could effectively control mulberry mites including adult mites and mite eggs, but more attention should be paid to the safety of silkworms during application in field.

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Duplex PCR detection of Burkholderia gladioli pv. alliicola and Erwinia chrysanthemi

YANG Wanfeng, LIU Yan, LU Chenchen, SHAO Peize, CHEN Yunqing, ZHAO Wenjun

2018, 30(3): 426-431. DOI: 10.3969/j.issn.1004-1524.2018.03.11

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The objective of this study is to establish a duplex PCR technology for simultaneously detecting Burkholderia gladioli pv. alliicola and Erwinia chrysanthemi. Based on the 16S-23S rRNA intergenic transcribed spacer sequence of B. gladioli pv. alliicola in GenBank, the primers B3/B6 were designed. The duplex PCR assay had been developed using the combining primers B3/B6 and ADE1/ADE2 which were specific primers to detect E. chrysanthemi. The reaction conditions were optimized and the specificity and sensitivity of the duplex PCR were tested. The expected DNA fragment could be specifically amplified from the genomic DNA of B. gladioli pv. alliicola and E. chrysanthemi. Specificity was confirmed using the duplex PCR assay to detect B. gladioli pv. alliicola and E. chrysanthemi in the artificially inoculated tulip leaf samples. The duplex PCR developed in this study can be used in detecting the two pathogens for imported tulip bulbs quarantine.

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Effects of different survival substrates on growth, development and reproduction of Tytthus chinensis

XIE Yukai, ZHENG Xusong, TIAN Junce, ZHANG Dayu, LYU Zhongxian

2018, 30(3): 432-436. DOI: 10.3969/j.issn.1004-1524.2018.03.12

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Tytthus chinensis (Stål) is a key predator of rice planthopper, a major pest of rice in China. Biological control of rice planthopper could be much more effective and feasible by improving the techniques of artificial breeding of natural enemies. The purpose of this study was to test the effect of different survival substrates, including kidney bean, wet cotton ball and rice stem, on the growth, development and reproduction of T.chinensis. The results showed that different survival substrates had significant influence on the development, survival and reproduction of T. chinensis. The survival rate of T. chinensis was the highest in the rice stem treatment, followed by the kidney bean treatment. The survival rate in wet cotton ball treatment was the lowest. Nymph duration in rice stem treatment was significantly shorter than the other two treatments, which indicated that kidney bean and wet cotton ball significantly impact the growth of T.chinensis. Though the fecundity in kidney bean treatment was significantly lower than those in rice treatment, the longevity, egg hatching rate and nymphal survival rate in kidney bean treatment were similar with those in rice stem treatment, and were significantly higher than those in wet cotton ball treatment. The population trend index of T. chinensis on rice stem and kidney bean treatment was 22.9 and 11.2 respectively, which meant T. chinensis could build a continuous population efficiently. The results indicated that kidney bean could be used as a feasible survival substitute for T. chinensis.

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Acute toxicity and safety assessment of nano-TiO₂ to aquatic organisms

LYU Lu, AN Xuehua, CHEN Liping, LIU Xinju, GUAN Wenbi, WU Shenggan, ZHAO Xueping

2018, 30(3): 437-444. DOI: 10.3969/j.issn.1004-1524.2018.03.13

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In order to assess the safety of nano-TiO₂ (nTiO₂) to aquatic organisms systematically, its acute toxicity to Scenedesmus obliquus, Daphnia magna Straus, Brachydanio rerio and Xenopus laevis tadpoles was studied, and its safety was evaluated. The results showed that the acute toxicities of nTiO₂ to Scenedesmus obliquus, Daphnia magna Straus, Brachydanio rerio and Xenopus laevis tadpoles were 0.140 mg·L^-1 (72 h-EC₅₀)、1.26 mg·L^-1 (48 h-EC₅₀)、22.0 mg·L^-1 (96 h-LC₅₀) and 5.02 mg·L^-1 (96 h-LC₅₀), respectively, and their toxictiy levels were high toxicity, moderate toxicity, low toxicity and moderate toxicity, respectively.

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Spatial heterogeneity of soil organic matter based on mind evolutionary computation radial basis function neural network

JIANG Yefeng, GUO Xi

2018, 30(3): 445-453. DOI: 10.3969/j.issn.1004-1524.2018.03.14

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In the present study, a method named MECRBF was proposed based on mind evolutionary computation radial basis function neural network. Its ability to reveal spatial heterogeneity of soil organic matter was compared with radial basis function neural network (RBF-Near) based on spatial coordinates and neighbor information, and ordinary Kriging method with Wannian County, Jiangxi Province as study area. To establish and validate, 954 soil samples were collected and randomly divided into 2 groups, i.e. modeling points (763) and validation points (191). Spatial distribution prediction capacities and prediction map of these methods were compared. It was shown that the root mean square errors (RMSE), mean absolute errors (MAE) and mean relative errors (MRE) of MECRBF in validation points was 0.50 g·kg^-1, 0.39 g·kg^-1, and 1.40 percent smaller than those of RBF-Near (P<0.05), respectively, and was 2.59 g·kg^-1, 1.89 g·kg^-1, and 7.76 percent smaller than those of ordinary Kriging (P<0.05), respectively. The prediction map obtained by MECRBF was more consistent with the actual geographical information than the others. Moreover, MECRBF method reduced the prediction errors. The proposed MECRBF could provide guidance to predict soil nutrients at county scale.

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Effects of nitrogen application on key enzymes gene expression and yield of nitrogen metabolism in flue-cured tobacco

LU Liming, ZENG Xiaomin, GU Huizhan, ZHANG Qili, YU Xiao, WANG Dong, HE Jixian, LI Liqin

2018, 30(3): 454-460. DOI: 10.3969/j.issn.1004-1524.2018.03.15

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In order to investigate the effects of nitrogen supply levels on nitrogen metabolism, key gene expression and nitrogen compounds content in flue-cured tobacco, a two-factor field experiment of nitrogen supply level and tobacco variety was conducted. The gene expressions of nitrate reductase (NR), glutamine synthetase (GS) and glutamate synthase (GOGAT) gene, as well as total nitrogen, nicotine and soluble protein contents in flue-cured tobacco leaves were measured at 45, 60 and 80 d after planting, respectively. It was shown that the expression of these three key nitrogen metabolism genes were influenced by nitrogen supply. Eighty days after planting, soluble protein contents in tobacco with high N (120 kg·hm^-2) was significantly (P<0.05) higher than that with low N (90 kg·hm^-2). Correlation analysis showed that NR gene expression was significantly (P<0.05) negatively correlated with nicotine content, and was significantly (P<0.01) positively correlated with soluble protein content in tobacco at 45 d after planting. GS gene expression and nicotine content showed a significantly (P<0.05) negative correlation at 60 d after planting. These results suggested that the nitrogen application level had significant effect on key gene expression in nitrogen metabolism of flue-cured tobacco, and the content of nitrogenous compounds in tobacco leaves could be regulated by adjusting the application amount of nitrogen.

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Design and experiment of natural gas-diesel dual-fuel engine based on SolidWorks

LI Lili, ZHAO Wuyun, TAN Wensheng, Wang Erhua

2018, 30(3): 461-469. DOI: 10.3969/j.issn.1004-1524.2018.03.16

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In the present study, ZS1115 diesel engine was selected as the test object. Natural gas (NG) intake valve, Venturi NG-air mixer and speed linkage system were mounted with little change in the structure of diesel engine. Three-dimensional (3D) model of dual-fuel engine was established with SolidWorks software according to size parameters, and its practicality was verified with motion simulation. Structural sizes and performance parameters of main parts were optimized with SolidWorks Motion, Simulation Xpress and Simulation Flow modules. Bench test results indicated that the dual-fuel engine based on SolidWorks run stably. Its power performance was greater than diesel engine, while NO_x and smoke emissions were lower. The best economical zone was around 1 700 r·min^-1 in the universal characteristics curve map and the curve extended along the Y axis, which suggested that NG-diesel dual-fuel engine was more suitable for agricultural working condition of low speed and large load changes.

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Change analysis of citrus total factor productivity in China

XU Xiao, YANG Jinxiu

2018, 30(3): 470-478. DOI: 10.3969/j.issn.1004-1524.2018.03.17

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This paper used the DEA-Malmquist index to measure the index of input and output of seven citrus regions in China within 2009-2015 aiming to discuss the change trend of total factor productivity of citrus production. The results showed that technical progress was the main factor of the total factor productivity of citrus in our country; under the negative contribution of technological progress, the total factor productivity of citrus production showed the trend of cyclical fluctuation; and the production of citrus was in the decline of pure technical efficiency, but the scale economy was effective. Therefore, it was crucial to achieve technical innovation, optimize material equipment level and improve orchard management level on the basis of stead increase of the existing scale efficiency.

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Internet plus seed industry: industrial convergence and industrial chain analysis

LI Jin, JIA Na, GUO Meirong, MA Chen

2018, 30(3): 479-488. DOI: 10.3969/j.issn.1004-1524.2018.03.18

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The structure and relationship among stakeholders of traditional industrial chain were analyzed, and the convergence point between internet and seed industry and two-way interactive development model were put forward. This paper suggested that in the internet environment, seed industry will gradually develop towards the direction of breeding specialization, production standardization, technical precision, service integration and management information. In view of the problems of the backward construction of germplasm resources, the difficulty of quality supervision and the low level of informatization of commercial breeding, this paper put forward some enlightenment to the sustained and healthy development of modern seed industry chain from three aspects: improving the construction of germplasm resource base, speeding up the construction of integrated industry chain and whole process informatization construction.

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Comprehensive evaluation on China's food import security based on super efficiency DEA model

WANG Ruifeng, LI Shuang, JIANG Yubo

2018, 30(3): 489-497. DOI: 10.3969/j.issn.1004-1524.2018.03.19

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On the basis of defining the connotation of grain and grain import safety, this paper analyzes the influencing factors of China's grain import safety from the aspects of grain quantity, grain quality, grain price, grain trade, national economy and ecological environment. Based on the super-efficiency DEA, this paper evaluates the safety situation of China's grain imports from 1992 to 2015, and tests the significance of the indicators by constructing t statistics to overcome the defect of the super-efficiency DEA model which can not judge whether the indexes are significant. The results show that China's grain import security is in a safe state during the period from 1992 to 2015. Grain imports have little impact on grain price security and ecological security in China, and have a greater impact on quantity safety, quality and safety, trade security and economic security.

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Study on formation mechanism and empirical verification of green-leap-forward development in mountainous area

KE Fuyan, XU Zhiyuan, ZHANG Weijiang, WU Yonghua

2018, 30(3): 498-506. DOI: 10.3969/j.issn.1004-1524.2018.03.20

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The new economic structure of the new green economy is coming into a long period of great development, and China is going to enter a new era of green development. Under this new development background, as the lagging area of China's economic development, mountain areas are not only necessary but also possible to achieve green-leap-forward development. According to the economic theories, this paper revealed the formation mechanism of green-leap-forward development in mountainous areas from the perspective of urban-rural industrial integration. The formation mechanism was verified by the experience of Anji County in Zhejiang Province, in order to reveal the feasibility of promoting the green-leap-forward development in mountainous areas through the integration of urban and rural industries. In addition, this paper also provided theoretical and empirical reference for the green-leap-forward development of other mountainous areas.

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Advances in porcine Toll-like receptor family (TLRs) and its application in resistance breeding

DAI Chaohui, FENG Haiyue, WU Shenglong, BAO Wenbin

2018, 30(3): 507-520. DOI: 10.3969/j.issn.1004-1524.2018.03.21

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Toll-like receptors (TLRs), as pattern recognition receptors, can not only recognize body's specific ligands and start signal transduction through a variety of signaling pathways (mediated by myeloid differentiation protein 88 or by the TLR domain protein of beta-interferon), which leads to specific immune responses, but also play important regulatory roles in some immune responses caused by mycoplasma, viruses, bacteria and other pathogens. Toll-like receptor family has become research hotspots in recent years because of its important immune regulations, which has important scientific significance and application prospect for the breeding of livestock and poultry. The types, functions, heritable variation and mediated signaling pathways of pig Toll-like receptor family were reviewed in this article, and the application of pig TLRs in disease resistance breeding was introduced intensively, which aimed to provide reference and basis for the research of gene function of pig Toll-like receptor family and screening effective genetic markers.

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