【目的】山羊关节炎-脑炎病毒（Caprine arthritis-encephalitis virus，CAEV）属于反转录病毒科慢病毒属成员，与梅迪-维斯纳病毒（Maedi visna virus）合称为小反刍动物慢病毒（Small ruminant lentiviruses）。该病毒可感染山羊和绵羊，以奶山羊最为易感。在过去四十年间，CAEV在我国传播扩散，并存在不同程度的感染，但有关该病毒基因组特征和可能的来源研究仍然较少，获取在中国流行的CAEV毒株的基因组数据对于开发诊断方法和根除相关疾病具有重要意义。【方法】本研究使用分段扩增和测序的方法获得了1989–1994年间从我国甘肃、贵州、陕西、山东和四川等地感染奶山羊中分离的5株CAEV病毒基因组，通过基因型分析、全基因组比对、遗传进化和种群结构分析来阐释该病毒基因组特征。【结果】我国CAEV与国外毒株基因组相似度为58%–93%，属于B型小反刍动物慢病毒，可进一步归为B1基因型。遗传进化分析结果显示本研究测定的5株病毒与其它两株中国毒株聚集成簇，亲缘关系最近，同源性为98.3%–99.3%；其次是与美国毒株Clements（GenBank登录号NC_001463.1），相似性为91.8%–92.3%；种群结构分析表明我国已测定的7株病毒拥有与其它已知毒株不同的祖先成分。【结论】跨度5年从我国不同省份分离的CAEV毒株具有高度同源性，分离株可能起源于非已知毒株的其它来源。【创新点】本研究完成了我国最早分离的5株CAEV病毒的基因组测序和基因特征分析，确认我国分离毒株高度同源，可能起源于特定的同一祖先，该结果为研制适用于我国CAEV检测的试剂和CAEV流行病学调查与防控奠定了基础。

双酰胺衍生物近年来在农药（特别是杀虫剂）的研究中被广泛关注。本文通过简单、环保的合成路线，设计、合成了一系列含有三氟甲基吡啶骨架的新型双酰胺衍生物，通过1H、19F和13C NMR以及HR-MS进行了确证。并测定了它们对小菜蛾（Plutella xylostella）和棉铃虫（Helicoverpa armigera）的杀虫活性，讨论了构效关系。部分化合物（D2、D5、D10、D21、D28、D29、D30和D33）在500 mg·L^-1时对小菜蛾具有100%杀虫活性。其中，化合物D33在100 mg·L^-1时对具有100%的杀虫活性，其LC₅₀值（致死中浓度）为3.7 mg L^-1，为该类化合物中最低值。分子对接结果表明，D33可嵌入鱼尼丁受体的活性口袋中，与商业杀虫剂氯虫苯甲酰胺类似，通过多个氢键与鱼尼丁受体相互作用。

本研究在引起北方玉米叶枯病的半活体性营养真菌——玉米大斑病菌（Setosphaeria turcica）基因组中鉴定了13个StCFEM蛋白。CFEM结构域的序列比对和WebLogo分析表明，StCFEM氨基酸高度保守，除StCFEM1、2、3和6外，整体上含有8个典型的半胱氨酸；系统发育分析表明，根据有无跨膜结构域的存在，13个蛋白（StCFEM1-13）可分为2个分支，其中6个有信号肽且无跨膜结构域的StCFEM蛋白（StCFEM3, 4, 5, 10, 12, 13）被假定为候选效应蛋白；对蛋白三级结构进行预测，发现候选效应蛋白的CFEM结构域可以形成螺旋结构，与白色念珠菌（Candida albicans）Csa2同源；进一步利用pSuc2t7M13or酵母分泌系统验证效应蛋白的分泌功能，结果发现6个候选效应蛋白均具有分泌能力，鉴定为分泌蛋白；转录组分析表明，6个候选基因在真菌侵染过程中不同时期均表达，其中SCFEM3、4、5和12在附着胞形成时期高度表达；我们还发现StCFEM3、4和5对BAX/INF诱导的本氏烟草程序性细胞死亡（PCD）没有影响，而StCFEM12可以抑制INF诱导的PCD，但对BAX诱导的PCD没有影响。本研究发现玉米大斑病菌（S. turcica ）CFEM蛋白家族共有13个成员，鉴定StCFEM12为候选效应子，为阐明CFEM蛋白在植物原发病过程中的作用奠定了基础。

小麦全蚀病 (Take-all) 是一种具有毁灭性的土传病害，培育抗病材料是控制该病害的重要途径之一。华山新麦草 (Psathyrostachys huashanica Keng) 是小麦品种改良的重要遗传资源，特别是小麦全蚀病稀缺的抗性资源。在本研究中，相比感病亲本7182，小麦-华山新麦草渗入系H148的全蚀病抗性得到了显著性提升。为了明确H148抗病性的遗传机制，我们构建了H148和西农585的F₂遗传分离群体，且利用植物数量遗传体系“主基因+多基因”混合遗传模型分离分析法对其研究发现，H148的全蚀病抗性受到两对主效基因的共同控制，这两对主效基因存在一定的加性、显性和上位性效应。同时，结合集群分离分析法 (Bulked Segregant Analysis, BSA) 和小麦660K基因芯片筛选出与抗病相关的外源特异性SNP，主要分布于小麦2A染色体。根据特异性SNP开发竞争性等位基因特异性PCR (Kompetitive allele specific PCR, KASP) 分子标记，对F₂群体进行基因分型，最终在2A染色体的68.8-70.1Mb区间内定位到一个主效的QTL。该目标区间在小麦参考基因组序列上存在62个候选基因，经基因功能注释显示，两个可编码蛋白的基因与系统性提升植物根系抗性相关，被预测可能参与了小麦对全蚀病的抗病反应。总之，小麦-华山新麦草渗入系H148的选育以及抗病QTL的定位，以期为小麦抗全蚀病分子辅助育种和抗病基因的精细定位提供一定的参考信息。

气候变化严重影响农业生产，危及粮食安全。中国是世界第二大玉米生产国，也是最大的玉米消费国。分析气候变化对玉米单产的影响可以为国家和国际经济和政治提供有效的指导。面板模型无法确定数据集的组间异方差、截面相关和组内自相关，因此我们采用广义最小二乘模型（FGLS）来评估1979-2016年气候变化对中国玉米单产的影响。得到以下结果：（1）在1979-2016年期间，温度升高对中国玉米单产产生了负面影响。温度每升高1℃，玉米单产减少5.19 kg 667 m^-2（1.7％）。在此期间，降水仅略有增加，因此其对玉米单产的影响可以忽略不计。降水量每增加1 mm，玉米单产将增加0.043 kg 667 m^-2（0.014％），这是微不足道的。（2）气候变化对玉米单产的影响在空间上有所不同，在中国南部地区受到的影响更大。在该地区，温度每升高1℃，玉米单产下降7.49 kg 667 m^-2，而温度对中国北方玉米单产的影响不明显。降水量每增加1 mm，华南玉米单产增加0.013 kg 667 m^-2，而华北玉米增加0.066 kg 667 m^-2。（3）玉米作物对气候变化的适应力强，1990-2016年期间的中国南北部温度的边际效应均小于1979-2016年期间。

长期秸秆还田是提高农田土壤有机碳储量的重要碳源，秸秆焚烧还田在我国南方也屡见不鲜。然而，长期稻草管理对土壤有机碳组分、酶活性及其相互关系的影响，以及其影响是否存在季节差异却尚未明确。我们基于2009年开始建立的长期定位试验平台，通过设置3个N、P、K等养分输入(包括秸秆/灰分和化学养分)的处理：秸秆不还田(CK)、秸秆还田(SR)和秸秆焚烧还田(SBR)，探讨长期秸秆还田条件对南方双季稻田土壤有机碳组分及土壤酶活性的影响。结果表明，与CK相比，长期秸秆还田有利于提高早稻产量(P=0.057)，并显著增加早晚稻田土壤的总有机碳（TOC）和微生物量碳(MBC)含量。而稻草焚烧还田对TOC无显著影响，但降低了早稻轻组有机碳（LFOC）和晚稻易氧化有机碳(EOC)含量，而显著增加了可溶性有机碳（DOC），且显著降低了土壤pH。我们研究还表明，长期秸秆还田条件下，MBC是评估双季稻系统土壤有机碳变化最敏感的指标；此外，SBR和SR对土壤酶活性的影响早晚稻稻田土壤呈现相反趋势，进而导致土壤有机碳组分含量存在季节差异，尤其是改变了土壤DOC含量，而早晚稻DOC与β-木糖苷酶均呈正相关。可见，秸秆还田较秸秆焚烧还田更有利于土壤有机碳组分的固持与提高，但其对晚稻土壤酶活性的负作用有待进一步研究。

Received  25 July, 2017    Accepted  19 February, 2018
 

Citrus yellow vein clearing virus (CYVCV) is considered as the causal agent of Citrus yellow vein clearing disease and belongs to the genus Mandarivirus in the family Alphaflexiviridae.  Capsid protein (CP) of CYVCV Chongqing isolate (CYVCV-CQ) was produced using a prokaryotic expression system and used as the immunogen for monoclonal antibody (MAb) production.  Four highly specific and sensitive murine MAbs and one polyclonal antibody were prepared in this study.  Titers of the four MAbs in ascites fluids ranged from 10^–6 to 10^–7 as determined by indirect enzyme-linked immunosorbent assay (ELISA).  Three serological assays, including dot enzyme-linked immunosorbent assay (dot-ELISA), tissue blot-ELISA, and double-antibody sandwich (DAS)-ELISA, were developed for quick and reliable detections of CYVCV in citrus samples.  The developed dot-ELISA and DAS-ELISA methods could detect CYVCV in the infected citrus leaf crude extracts diluted at 1:2 560 and 1:10 240 (w/v, g mL^–1), respectively.  The detection result of 125 citrus leaf samples collected from citrus groves in Yunnan Province and Chongqing Municipality of China showed that approximately 36% samples were positive for CYVCV.  This virus was, however, not detected in any sample collected from Zhejiang or Jiangxi Province, China.

Aphid-borne Zucchini yellow mosaic virus (ZYMV) is one of the most economically important viruses of cucurbitaceous plants.  To survey and control this virus, it is necessary to develop an efficient detection technique.  Using purified ZYMV virion and the conventional hybridoma technology, three hybridoma cell lines (16A11, 5A7 and 3B8) secreting monoclonal antibodies (MAbs) against ZYMV Zhejiang isolate were obtained.  The working titers of the ascitic fluids secreted by the three hybridoma cell lines were up to 10^–7 by indirect enzyme-linked immunosorbent assay (ELISA).  All MAbs were isotyped as IgG1, kappa light chain.  Western blot analysis indicated that the MAb 3B8 could specifically react with the coat protein of ZYMV while MAbs 5A7 and 16A11 reacted strongly with a protein of approximately 51 kDa from the ZYMV-infected leaf tissues.  According to this molecular weight, we consider this reactive protein is likely to be the HC-Pro protein.  Using these three MAbs, we have now developed five detection assays, i.e., antigen-coated-plate ELISA (ACP-ELISA), dot-ELISA, tissue blot-ELISA, double-antibody sandwich ELISA (DAS-ELISA), and immunocapture-RT-PCR (IC-RT-PCR), for the sensitive, specific, and easy detection of ZYMV.  The sensitivity test revealed that ZYMV could be readily detected respectively by ACP-ELISA, dot-ELISA, DAS-ELISA and IC-RT-PCR in 1:163 840, 1:2 560, 1:327 680 and 1:1 310 720 (w/v, g mL^–1) diluted crude extracts from the ZYMV-infected plants.  We demonstrated in this study that the dot-ELISA could also be used to detect ZYMV in individual viruliferous aphids.  A total of 275 cucurbitaceous plant samples collected from the Zhejiang, Jiangsu, Shandong and Hainan provinces, China, were screened for the presence of ZYMV with the described assays.  Our results showed that 163 of the 275 samples (59%) were infected with ZYMV.  This finding indicates that ZYMV is now widely present in cucurbitaceous crops in China.  RT-PCR followed by DNA sequencing and sequence analyses confirmed the accuracy of the five assays.  We consider that these detection assays can significantly benefit the control of ZYMV in China.  

Rice ragged stunt virus (RRSV) is a serious rice disease in Asia, causing serious yield losses on rice. The capsid protein (CP) gene of the major outer capsid protein of RRSV was expressed in Escherichia coli BL21 (DE3) using the pMAL-C2X expression vector. The recombinant protein was used as the immunogen to immunize BALB/c mice. A hybridoma cell line 8A12 secreting monoclonal antibody (MAb) against RRSV was obtained by fusing mouse myeloma cells (Sp 2/0) with spleen cells from the immunized BALB/c mice. Western blot analysis showed that the MAb 8A12 can specifically react with RRSV CP. Using the MAb, an antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA), a dot enzyme-linked immunosorbent assay (dot-ELISA), and immunocapture-RT-PCR (IC-RT-PCR) assay were developed to detect RRSV. The established ACP-ELISA, dot-blot ELISA and IC-RT-PCR methods could detect RRSV in infected rice tissue crude extracts with dilutions of 1:40 960, 1:1280 and 1:655360 (w/v, g mL-1), respectively. The ACP-ELISA and dot-blot ELISA methods could detect RRSV in infected insect vector crude extracts with dilutions of 1:12800 and 1:1600 (an individual planthopper μL-1), respectively. The field survey revealed that Rice ragged stunt disease occurs on rice in Hainan, Yunnan, Guangxi, Sichuan, Guizhou, Fujian, Hunan, Jiangxi and Zhejiang in China.

A spotted-leaf mutant of rice HM143 was isolated from an EMS-induced IR64 mutant bank. Brown lesions randomly distributed on leaf blades were observed about 3 wk after sowing. The symptom lasted for the whole plant growth duration. Histochemical analysis indicated that cell death occurred in and around the site of necrotic lesions accompanied with accumulation of hydrogen hyperoxide. Agronomic traits were largely similar to the wild type IR64 except seed setting rate and 1 000-grain weight which were significantly decreased in the mutant. Disease resistance of the mutant to multiple races of Xanthomonas oryzae pv. oryzae was significantly enhanced. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively termed splHM143. In addition, using molecular markers and 1 023 mutant type individuals from an F2 segregating population derived from the cross HM143/R9308, the spotted-leaf gene was finally delimited to an interval of 149 kb between markers XX25 and ID40 on the long arm of chromosome 4. splHM143 is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region.

Downy mildew (DM), caused by the fungus Peronospora parasitica, is a destructive disease of radish (Raphanus sativus L.) worldwide. Host resistance has been considered as an attractive and environmentally friendly approach to control the disease. However, the genetic mechanisms of resistance in radish to the pathogen remain unknown. To determine the inheritance of resistance to DM, F1, F2 and BC1F1 populations derived from reciprocal crosses between a resistant line NAU-dhp08 and a susceptible line NAU-qtbjq-06 were evaluated for their responses to DM at seedling stage. All F1 hybrid plants showed high resistance to DM and maternal effect was not detected. The segregation for resistant to susceptible individuals statistically fitted a 3:1 ratio in two F2 populations (F2(SR) and F2(RS)), and 1:1 ratio in two BC1F1 populations, indicating that resistance to DM at seedling stage in radish was controlled by a single dominant locus designated as RsDmR. A total of 1 972 primer pairs (1036 SRAP, 628 RAPD, 126 RGA, 110 EST-SSR and 72 ISSR) were screened, and 36 were polymorphic between the resistant and susceptible bulks, and consequently used for genotyping individuals in the F2 population. Three markers (Em9/ga24370, NAUISSR826700 and Me7/em10400) linked to the RsDmR locus within a 10.0 cM distance were identified using bulked segregant analysis (BSA). The SRAP marker Em9/ga24370 was the most tightly linked one with a distance of 2.3 cM to RsDmR. These markers tightly linked to the RsDmR locus would facilitate marker-assisted selection and resistance gene pyramiding in radish breeding programs.

The spatial-temporal patterns of grain production and consumption have an important influence on the effective national grain supply on condition of tight balance in the total grain amount in China. In this paper, we analyze the spatial-temporal patterns of grain production, consumption and the driving mechanism for their evolution processes in China. The results indicate that both gravity centers of grain production and consumption in China moved toward the northern and eastern regions, almost in the same direction. The coordination of grain production and consumption increased slightly from 1995 to 2007 but decreased from 2000 to 2007. There is a spatial difference between the major districts of output increase and the strong growth potential in grain consumption, which indicates an increasing difficulty in improving the regional coordination of grain production and consumption. The movement of the gravity center of grain production is significantly correlated with regional differences in grain production policy, different economic development models, and spatial disparity of land and water resource use. For grain consumption, the main driving factors include rapid urbanization, the upgrade of food consumption structure, and distribution of food industries.

Dairy industry has become an increasingly important enterprise in China as people’s dietary preferences and composition have changed dramatically with rapid economic development in the past several decades. A number of problems, however, exist in China’s relatively young dairy industry, including the imbalanced allocation of profits throughout the dairy supply chain. One of the root causes of the melamine infant powered milk scandal in 2008 was the unfair profit allocation mechanism in dairy supply chain. The revenue sharing contract approach has proven to be effective in generating market shares and total profits. In this study, we apply the three-stage revenue sharing contract model of Giannoccaro and Pontrandolfo (2004) in an analysis of dairy supply chain to explore its problems in profit allocation and possible solutions to them. The analysis was conducted by a case study of Hohhot, often called as “milk capital of China”. Our results show that the current profit distribution in the dairy supply chain is not balanced: the supermarket’s profit>farmer’s profit>manufacturer’s profit. Under the revenue sharing contract setting, the dairy industry’s total profit increased by 12.49%. By exploring different parameters in the revenue sharing contract model, we have found that a win-win situation can be created among all the members of the supply chain. In dairy supply chain, the ratio of the revenue reserved for the supermarket itself is equal or greater than 47% and the ratio of the revenue reserved for the manufacturer itself is between 46.4 and 50.2%. The values of the parameters that generate a sustainable or win-win situation are related to the bargaining position in the dairy supply chain. The revenue sharing contract has proven to be effective and desirable by all the dairy chain partners in dairy supply chain. The results of this study provide relevant information for improving the dairy supply chain structure and the revenue sharing contract model can be applied to other industries, sectors and regions.

Seasonal hair follicle activity and fibre growth in some Cashmere-bearing goats (Caprus hircus) is a cyclic process that is well characterized morphologically but understood incompletely at the molecular level. As an initial step in discovering regulators in hair-follicle activity and cycling, we used qPCR to investigate 19 genes expression in Cashmere goat side skin from 12 mon. Many of these genes may be associated with the hair follicle development-relevant genes (HFDRGs) in the literature. Here we show that Hoxc13/β-catenin gene associated with the follicle activity. In addition, Hoxc13 was found to be expressed with an drastic increase between July and November for melatonin treatments. To further investigate the role of Hoxc13 on HFDRGs, fibroblasts and keratinocytes from Cashmere goat skin were transfected with p-ECFPHoxc13. The result suggested that overexpression of Hoxc13 gene decreased HFDRGs with negative role for hair follicle development and increase HFDRGs with positive role for hair follicle development in vitro. These findings provide data on the Hoxc13 expression profile of normal Cashmere goat skin and Cashmere goat skin with melatonin treatment, and demonstrate hair-follicle-activity dependent regulation of Hoxc13 expression.

Tomato yellow leaf curl virus (TYLCV) is a species of the family Geminiviridae, causing serious yield losses in tomato production. The coat protein (CP) gene of TYLCV isolate SH2 was expressed in Escherichia coli BL21 (DE3) using pET- 32a as the expression vector. The recombinant protein was purified through Ni+-NTA affinity column and used to immunize BALB/c mice. Three hybridoma cell lines (2B2, 2E3 and 3E10) secreting monoclonal antibodies (MAbs) against TYLCV CP were obtained by fusing mouse myeloma cells (Sp 2/0) with spleen cells from the immunized BALB/c mouse. The titers of ascitic fluids of three MAbs ranged from 10-6 to 10-7 in indirect-ELISA. Isotypes and subclasses of all the MAbs belonged to IgG1, κ light chain. Triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA) showed that the MAb 3E10 could react with five begomoviruses infecting tomato, while the other two (2B2 and 2E3) mainly reacted with TYLCV. TAS-ELISA was set up using the MAb 3E10, and the established method could successfully detect virus in plant sap at 1:2 560 (w/v, g mL-1). Detection of field samples showed that begomoviruses were common in tomato crops in Zhejiang Province, China.

The embryo, cytoplasmic, and maternal heterosis for erucic acid content (EAC) and glucosinolate content (GLS) of rapeseed (Brassica napus L.) were studied by using the genetic models for quantitative traits of seeds in diploid crops. Eight parents were included in a diallel mating design in two years. It was found that the heterosis of EAC and GLS was simultaneously controlled by genetic main effects and genotype×environment (GE) interaction effects. The general heterosis of most crosses for EAC was significantly positive, while it was not for GLS. The general heterosis was more important for two quality traits of rapeseed because of the low GE interaction heterosis in both years, especially for GLS. Among different genetic systems, significant positive embryo general heterosis and the negative maternal general heterosis were found for EAC and GLS in most hybrid crosses. Some hybrids with significant negative interaction heterosis were detected for either of EAC or GLS. In general, maternal general and interaction heterosis was more important for reducing EAC and GLS of rapeseed.