基于基因组序列分析的烟草轻绿花叶病毒江苏辣椒分离物侵染性克隆构建

【目的】烟草花叶病毒属（Tobamovirus）是危害辣椒、烟草等茄科作物的主要病毒之一,严重影响蔬菜作物的种植和生产。本研究旨在探明侵染江苏省南京市辣椒的烟草轻绿花叶病毒（tobacco mild green mosaic virus,TMGMV）分离物（TMGMV-JS）的基因组结构特征、系统进化关系及其致病性,为TMGMV的防控提供科学依据。【方法】从江苏省南京市采集的辣椒病样,提取总RNA,利用TMGMV特异检测引物确认阳性后,设计病毒特异性全长引物扩增TMGMV-JS全基因序列,通过同源重组的方法克隆至pCB301植物表达载体上,获得TMGMV-JS分离物基因组序列和全长cDNA侵染性克隆。BLAST分析TMGMV-JS分离物与已报道分离物的同源性,利用MEGA7软件的邻接法进行系统进化分析。将侵染性克隆通过农杆菌浸润本氏烟和辣椒,经RT-PCR和Western blot检测验证侵染效果,测定TMGMV-JS分离物的致病性。【结果】侵染江苏省南京市辣椒的TMGMV全长序列为6 356 nt,编码4个功能蛋白,分别为126K复制相关蛋白、183K复制酶、运动蛋白MP和外壳蛋白C...     

Effect of Manure Application on Nitrogen Use Efficiency of Crops in China: A Meta-Analysis

【Objective】 Combined chemical fertilizers with manure is one of the important approaches to improve the nitrogen use efficiency (NUE) of crops. Nowadays, rare studies focused on systematic comparison and analysis of combine chemical fertilizers with manure on nitrogen use efficiency in different regions of China. In addition, NUE is affected by many factors, such as nitrogen application amount, soil properties and the climatic conditions and even most of them are in the specific regions. Therefore, this study was carried out to explore the effects of chemical fertilizers combined with manure on NUE, and quantify the response of NUE to manure application in different soils and climatic regions, so as to give the guidance on sustaining regional agricultural development and provide an important theoretical basis for reducing fertilizer application. 【Method】 This study was conducted based on a database of NUE including 412 sets on NPKM vs. NPK, which were collected from 110 published articles with wheat, maize and rice. We analyzed the differences of NUE between the treatment of NPK and NPKM in five regions in China by Meta-analysis, and quantified the contribution of main controlling factors on positive manure affects by Random Forest analysis. 【Result】 Compared with NPK, NPKM treatment increased the NUE by 3.6%. NPKM treatment significantly increased the NUE of crops in all regions except the Northeast China. The highest enhancement was found at Northwestern China, followed by Northern China, Southern Region and Eastern China. Soil organic matter, pH, available potassium and total nitrogen were the main factors affecting the “positive effect” of manure on NUE. The increment of NUE by manure application was higher in the soils with lower organic matter content than that in the soils with high organic matter content. The increase of NUE in alkaline soils with manure applied was 1.3 and 1.8 times higher than those on neutral and acidic soils, respectively. The improvement of NUE by manure application varied among climate regions: temperate continental climate zone>temperate monsoon climate zone>subtropical monsoon climate zone. 【Conclusion】 The application of manure could significantly increase the NUE of crops, especially in northwestern areas with low organic matter content and less rainfall.     

番茄褪绿病毒的进化动态与适应性进化特征

【目的】番茄褪绿病毒（tomato chlorosis virus,ToCV）是长线形病毒科（Closteroviridae）毛形病毒属（Crinivirus）成员,现已成为我国番茄和其他蔬菜作物上最为常见的病毒之一。研究旨在查明ToCV的进化历史,尤其是该病毒何时何地传入我国,并阐明其适应性进化机制。【方法】根据ToCV外壳蛋白（coat protein,CP）基因两侧保守区设计1对特异性引物,对随机抽取的13个ToCV分离物进行扩增克隆,将测序获得的新序列与GenBank下载的含有采样时间和地理信息的序列合并得到103条ToCV CP基因序列,采用日期随机化检验（date-randomization test,DRT）检测数据集中的时间信号,并应用贝叶斯谱系动力学框架重建该病毒的进化动态。同时,应用系统发育与性状关联分析（phylogeny-trait association analysis）评估地理因素对ToCV适应性进化的影响。【结果】13 个ToCV分离物均成功扩增出预期大小（约800 bp）的特异性片段,核苷酸序列与已报道的ToCV不同分离物CP 基因序列一致性均在98%以上;基于聚类排列的日期随机化检验结果显示,通过实际采样时间和日期随机化的数据集分别推断获得的替代速率在95%置信区间之间没有存在重叠,表明本研究的数据集具有足够的时间信号,可以用于后续的贝叶斯分子定年（Bayesian molecular dating）分析。贝叶斯系统发育分析显示ToCV的最近共祖时间（the most recent common ancestor）为1920年（95%置信区间：1849—1976）,该病毒约于2005年左右从美国引入中国。该病毒的CP基因替代速率约为1.12×10 ^-3替代/位点/年（95%置信区间：6.08×10 ^-4—1.73×10 ^-3）,与动物RNA病毒的相当,表明ToCV正处于快速进化之中。此外,系统发育分析与性状关联分析结果显示ToCV分离物与其来源地区的关联系数（association index）、简约分值（parsimony score）和最大单系分支（maximum monophyletic clade）统计检验均呈极显著水平（P<0.01）,表明地理因素与ToCV适应性进化之间存在很强的关联性。【结论】ToCV正处于快速进化动态,该病毒的适应性进化主要受地理因素所驱动。研究结果将有助于增加对ToCV流行病学的认识,可为制定有效的防控策略提供依据。     

Potential N mineralization and availability to maize in black soils in response to soil fertility improvement in Northeast China

Purpose

Understanding the soil nitrogen (N) mineralization potential (N₀) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing over-fertilization, which lead to negative environmental impacts.

Methods

Five black soils with different levels of fertility were selected in Northeast China. The N₀ and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature.

Results

Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest N₀ values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement.

Conclusions

Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.

     

Effects of fencing on vegetation and soil restoration in a degraded alkaline grassland in northeast China

In order to restore a degraded alkaline grassland, the local government implemented a large restoration project using fences in Changling county, Jilin province, China, in 2000. Grazing was excluded from the protected area, whereas the grazed area was continuously grazed at 8.5 dry sheep equivalent（DSE）/hm2. In the current research, soil and plant samples were taken from grazed and fenced areas to examine changes in vegetation and soil properties in 2005, 2006 and 2008. Results showed that vegetation characteristics and soil properties improved significantly in the fenced area compared with the grazed area. In the protected area the vegetation cover, height and above- and belowground biomass increased significantly. Soil pH, electrical conductivity and bulk density decreased significantly, but soil organic carbon and total nitrogen concentration increased greatly in the protected area. By comparing the vegetation and soil characteristics with pre-degraded grassland, we found that vegetation can recover 6 years after fencing, and soil pH can be restored 8 years after fencing. However, the restoration of soil organic carbon, total nitrogen and total phosphorus concentrations needed 16, 30 and 19 years, respectively. It is recommended that the stocking rate should be reduced to 1/3 of the current carrying capacity, or that a grazing regime of 1-year of grazing followed by a 2-year rest is adopted to sustain the current status of vegetation and soil resources. However, if N fertilizer is applied, the rest period could be shortened, depending on the rate of application.     

不同肥力潮土的酶活计量比特征及其与微生物量的关系

【目的】研究不同肥力土壤上胞外酶活性,阐明胞外酶活性计量比特征及其影响因素,为阐明土壤生物肥力差异的机制与土壤培肥提供理论依据。【方法】选取了高、中、低肥力的潮土,分析其微生物量碳、氮（SMBC、SMBN）含量以及β-1, 4-葡萄糖苷酶（β-1, 4-glucosidase,BG）、纤维二糖水解酶（Cellobiohydrolase,CBH）、β-1, 4-N-乙酰葡糖氨糖苷酶（β-1, 4-N-acetylglucosaminidase,NAG）、亮氨酸氨基肽酶（leucine aminopeptidase,LAP）和碱性磷酸酶（alkaline phosphatase,AP）活性。采用生态化学计量学方法分析该5种酶活性在不同肥力土壤间的差异,以及酶活与土壤微生物量间的定量关系。【结果】高肥力土壤SMBC是中肥力土壤的2.6倍,低肥力土壤的5.8倍;高肥力土壤SMBN为中肥力土壤的3.1倍,低肥力土壤的5.5倍。SMBC/SMBN在不同肥力土壤间无显著差异。土壤碳氮磷转化酶活性和综合酶指数均表现为高肥力土壤>中肥力土壤>低肥力土壤,且土壤胞外酶活性与微生物量碳氮表现为直线正相关关系。SMBC和SMBN每增加1 mg·kg^-1,（BG+CBH）和（NAG+LAP）活性分别可提高0.134和10.53 nmol·g^-1·h^-1。ln (BG+CBH):ln (NAG+LAP)和ln (BG+CBH):ln AP均小于1,表明碳源是潮土养分转化的首要限制因素。高肥力土壤上碳、氮、磷酶活比例较低肥力土壤更接近适宜值。【结论】潮土上应配施有机肥或进行秸秆还田,保证充足的碳源以解决养分有效性限制的问题,促进氮磷的养分循环转化。适宜的活性碳氮磷比例是高肥力土壤高产高效的重要机制之一。     

免疫程序与母源抗体对H5禽流感疫苗免疫鸭和鹅HI抗体水平的影响

对不同日龄与母源抗体水平的鸭和鹅，用H5亚型禽流感疫苗免疫后，其HI抗体消长情况进行了比较和观察，结果，初生水禽3日龄首免即可对禽流感疫苗（H5亚型）产生良好的免疫应答；雏鹅母源抗体几乎以每4d下降1个HI抗体效价单位的速度消退；母源抗体对H5禽流感疫苗免疫后的HI抗体水平存在一定的干扰作用；加强免疫鸭和鹅所产生的H5 HI抗体水平及其维持时间与仅免疫一次的鸭和鹅所产生的抗体水平之间存在显著差异；鸭和鹅免疫H5禽流感疫苗后第25～30d H5 HI抗体水平达到高峰。     

江苏省农业机械化需求及发展对策

1江苏省农机化需求状况的调查与分析 　　为了较全面客观地预测江苏省未来一定时期内农业机械化发展趋势,从宏观上把握农业机械化发展的方向,我们在全省范围内对江苏今后5-10年内重点发展的农业机械化技术进行了问卷调查,并结合实地调研的情况分析探讨江苏农机化发展的重点和应采取的政策措施.     

河南鸡公山自然保护区典型森林类型土壤微生物群落功能多样性

Biolog EcoTM微平板技术是研究微生物群水平多样性的一种重要方法。通过该方法对河南鸡公山自然保护区3种主要森林类型(落叶阔叶林、针阔混交林、杉木林)的土壤微生物群落多样性进行研究,结果显示:土壤微生物对单一碳源利用强度随着培养时间的增加呈递增的趋势,落叶阔叶林土壤微生物活性高于其他两种森林类型。3种森林类型土壤微生物对碳源利用差异性显著(p<0.01),森林植被类型直接影响土壤微生物功能多样性。分析表明,氨基酸是研究区域森林土壤微生物敏感碳源。