microRNAs（miRNAs）是广泛存在于哺乳动物中的一种微小、非编码RNA，可以通过靶向吸附调节下游基因的表达，参与多种生物学过程。虽然关于 miRNAs 调控哺乳动物毛色的研究取得了一定的成果，但其调控网络尚不完善，仍需要不断深入研究。前期测序发现，miR-370-5p在白色绵羊皮肤中的表达水平显著高于黑色绵羊，推测其可能参与绵羊皮肤黑色素生成。本研究以绵羊黑色素细胞为研究对象，探究miR-370-5p在绵羊黑色素细胞中的作用。表型检测发现，高表达的miR-370-5p可以显著抑制（P=0.001）酪氨酸酶活性，从而显著降低（P<0.001）黑色素的产生；CCK 8实验检测发现，黑色素细胞转染miR-370-5p后的第4天至第5天，细胞的增殖速率显著降低（P<0.01）。靶基因预测发现，丝裂原活化蛋白激酶8（Mitogen-activated protein kinases, MAP3K8）的3'非翻译区（Untranslated Region, UTR）存在miR-370-5p的靶向结合位点，推测两者可能存在靶向调控关系。双荧光素酶报告载体实验结果显示，miR-370-5p可以靶向吸附MAP3K8-3’UTR。原位杂交实验显示，MAP3K8广泛表达于黑素细胞的细胞质。定量RT-PCR和Western blot结果显示，miR-370-5p显著抑制（P<0.01）MAP3K8的表达。以上结果表明，miR-370-5p可以靶向结合MAP3K8-3’UTR，抑制其表达。siRNA干扰结果显示，黑素细胞中干扰MAP3K8的表达可以显著抑制（P<0.01）细胞增殖，降低（P<0.001）黑色素生成，影响趋势与过表达miR-370-5p一致。靶基因拯救实验结果显示，黑色素细胞中共转染miR-370-5p和MAP3K8-cDNA（含有miR-370-5p靶向结合位点）载体，可以显著上调（P≤0.001）MAP3K8的表达，显著促进细胞增殖（P<0.001）和黑色素产生（P<0.01）。以上结果表明， miR-370-5p通过靶向抑制MAP3K8表达，抑制绵羊黑色素细胞增殖、降低黑色素产量。本研究通过miRNA过表达探明了miR-370-5p对黑色素细胞增殖、酪氨酸酶活性及黑色素产量的影响；通过靶基因干扰、拯救实验解析了miR-370-5p抑制黑色素细胞增殖、酪氨酸酶活性及黑色素生成的分子机制，有助于丰富miRNAs参与毛色形成的调控机制，为后续毛用动物毛色改良提供参考。

株高是影响甘蓝型油菜产量、收获指数和抗倒伏性的关键株型特征，然而，油菜株高的遗传调控机制仍不清楚。本研究利用EMS诱变获得了一个半矮杆突变体df34，遗传分析结果表明，df34的半矮杆性状由一对半显性基因控制。利用BSA-Seq方法将目的基因定位到C3染色体上，命名为BnaSD.C3。随后，利用图位克隆的方法，将BnaSD.C3精细定位到“Darmor-bzh”基因组的297.35 kb区间内。然而，在“Darmor-bzh”基因组上的这一区间内，没有潜在的调控株高性状的候选基因。结合基因组重测序、转录组测序、植物激素分析、结构变异分析和基因功能注释等信息，在“ZS11”参考基因组上，发现BnaC03G0466900ZS和BnaC03G0478900ZS为BnaSD.C3的重要候选基因。本研究为甘蓝型油菜矮化及株型育种提供了新的基因资源，为解析甘蓝型油菜株高的遗传调控机制提供了新的见解。

利用籼/粳交稻(IJHR)杂种优势是进一步提高水稻产量的有效途径。合理施用氮肥对于充分发挥IJHR杂种优势，实现其巨大产量潜力起重要作用。但是，IJHR产量和氮肥利用率对施氮量的响应及其生理机制仍然不清楚。本研究旨在阐明这一问题。于2018-2019年，选用目前生产上应用的3个水稻品种，即IJHR品种甬优2640、粳稻品种连粳7号和籼稻品种扬稻6号，大田种植，设置6种施氮量（0、100、200、300、400和500 kg hm^-2）处理。结果表明，各供试品种的产量均随着施氮量的增加呈现先增加后降低的趋势，甬优2640产量在施氮量为400 kg hm^-2时最高，为13.4 t hm^-2，连粳7号和扬稻6号产量在施氮量为300 kg hm^-2时最高，分别为9.4 t hm^-2和10.6 t hm^-2。在相同尤其是在较高的施氮量下，甬优2640产量和氮肥利用效率均高于连粳7号和扬稻6号。与连粳7号或扬稻6号相比，甬优2640具有较好的生理性状，如较高的根系氧化力和叶片光合速率，根和叶中较高的细胞分裂素含量，灌浆期茎中同化物较多地向籽粒转运。以上结果说明，无论是在低施氮量还是在高施氮量下，IJHR均能较常规水稻获得较高的产量和氮肥利用效率。IJHR较好的地上部和根系性状是其获得较高产量和氮肥利用效率的重要原因，而IJHR植株中较高的细胞分裂素含量则在响应施氮量中起着至关重要的作用，并有利于其他生理过程。

本研究依托于29年的黑土长期定位试验，供试作物为玉米。肥料试验包括不施肥对照（CK）、施氮、钾肥（NK）、氮磷钾平衡施肥（NPK）、氮磷钾+有机肥（NPKM）共4 个处理。选取了2018年0-20，20-40，40-60 cm的土壤样品，测定土壤性质，并采用Hedley连续浸提法分析了土壤磷形态。试验结果表明，长期有机无机配施处理（NPKM）促进了磷在土壤剖面的积累，与初始值相比，其全磷含量增加了0.6-1.6倍。NPKM处理中，其剖面的有效磷含量也远远超过了黑土的环境阈值（50.6 mg kg^-1）。此外，NPKM处理中土壤剖面各活性和中活性态无机磷（NaHCO₃-Pi，NaOH-Pi和diluted HCl-Pi）的含量与比例显著高于NPK处理。这表明，NPKM处理可促进土壤稳定态磷向活性较高的磷形态转化。这可能是由于NPKM降低了土壤对磷的固定。冗余分析结果表明，由施肥引起的土壤有机质、Mehlich3-Fe和络合态铝氧化物含量的增加是影响黑土0-20 cm磷形态差异的主要因素。土壤矿物组分，如游离态的铁氧化物、碳酸钙是影响黑土深层土壤磷形态差异的主要因素。这表明黑土磷的转化过程同时受土层和施肥的影响。由于磷在不同土层中的积累和转化导致的高含量的有效磷以及有机肥的施用增加的活性较高的磷形态含量，我们在生产实践中应适当的减少或优化化肥的投入，以实现农业与环境的可持续发展。

本研究利用已公布的4165个来自于全世界196个品种的山羊线粒体D_Loop序列，进行核苷酸多样性、单倍型构建、单倍型多样性、群体系统发育学研究、中性检验及群体遗传距离等一系列遗传参数进行评估。在全部个体的401 bp片段长度的D_Loop区域内共鉴定得到301个多态位点，总体核苷酸多样性为0.03471；构建获得并构建2409个D_Loop单倍型，单倍型平均多样性为0.9983。系统发育分析表明，98.92%的单倍型被聚类为已知的6个山羊线粒体D_loop单倍型簇，其中单倍型A所占比例最大(86%)，D_Loop单倍型B簇在中国山羊中出现频率最高。中国西南地区山羊群体中发现了两个未知的D_Loop单倍型簇(Unknown I和Unknown II)。分子方差分析(AMOVA)和群体间成对差异(PiXY)研究结果表明，不同品种家养山羊间群体变异较小，群体遗传分化与地理分布不完全一致，表明群体间广泛存在遗传物质交流。中性检验(Tajima‘D和Fu’Fs检验)和错配分布研究结果表明，单倍型簇B、C和G存在群体扩张历史。较其他野羊，Capra aegagrus与家养山羊系统发育关系最为密切，并可能贡献于山羊A、B、C和F单倍群簇的驯化起源。本研究表明线粒体D_Loop单倍型B簇可能起源于中国或在山羊驯化早期已迁至中国，在中国西南地区山羊群体中两个未知的D_Loop单倍型簇的发现表明中国西南地区可能具有独特的山羊母系背景或驯化历史；Capra aegagrus是最可能的家养山羊野生祖先，并可能贡献于山羊A、B、C和F单倍群簇的驯化起源。本研究利用大样本量全世界山羊线粒体D_Loop序列数据集分析有助于更好的理解世界范围内山羊母系驯化起源及基因流动的历史变化，为进一步明确世界山羊群体迁徙的演变历史及种群系统发育定位提供了宝贵的理论依据。

氮肥在中国的过度使用及其对农业生产的不利影响已在国内和国际引起关注。除公共机构推动的多种促进农业可持续发展的实践外，借助信息通讯技术或数字服务手段推动可持续农业实践的私人部门创新和创业正在崭露头角。本研究探讨了一个创业企业依托信息技术提供农业技术推广服务对农户采用可持续农业实践的影响。结果表明，依托信息技术的农业社会化服务并没有显著减少小麦种植中的氮肥使用量。然而，信息技术在农业社会化服务的使用却促使农民的氮肥施用趋向于可持续和精准施肥。创业企业的此种创业模式在农户参与性和财务可持续性方面面临巨大挑战。

选用氮高效水稻品种可减少氮肥的投入而不降低产量，但有关氮高效水稻品种的形态生理特征不清楚。本研究以3个氮高效粳稻品种和3个氮低效粳稻品种为材料并种植于大田，设置不施氮(0 kg N ha^-1)和常规施氮量(180或200 kg N ha^-1)2种处理。结果表明，与氮低效品种相比，氮高效品种在2种施氮量情况下均具有较高的总颖花量、结实率、产量和氮肥利用率。氮高效品种在穗分化期具有较高的根系氧化力、根干重、根长和根直径，灌浆期具有较高的粒叶比和茎蘖成穗率，抽穗后具有较高的氮转运量、干物质积累、良好的叶片性状包括较高的剑叶厚度、比叶重、光合速率，较高的核酮糖-1,5-二磷酸羧化酶/加氧酶、叶绿素、氮和可溶性糖含量，以及较优的冠层结构（较高的氮消减系数与消光系数之比）。上述形态生理性状与产量及氮肥利用率呈显著或极显著正相关。这些性状可作为培育和筛选氮高效水稻品种的指标。

葡萄是一种重要的水果作物，我国的葡萄产量约占全球总产量的15%，位列世界第一。扦插是葡萄快速繁殖的重要手段，然而近两年来我们在日照莒县的葡萄扦插苗圃中发现大量葡萄新芽受病菌侵染而腐烂死亡，给葡萄苗生产造成严重损失。为了明确引起该现象的原因，在本研究中，我们通过组织分离法获得了36个真菌菌株，经菌落和分生孢子的形态鉴定以及利用转录间隔区(ITS)、翻译延伸因子（Tef）和β-微管蛋白（Tub2）进行多基因系统发育分析鉴定，36个菌株分别属于Sclerotium, Neopestalotiopsis, Botryosphaeria, Fusarium, Clonostachys 和Botrytis 6个属，而其中的N. eucalypti是一种首次在葡萄上分离到的菌株。按照柯赫氏法则，对葡萄枝蔓进行离体和活体接种，结果显示N. eucalypti引起葡萄枝蔓的组织腐烂坏死，并在坏死斑表面产生大量黑色分生孢子盘。本文首次报道了N. eucalypti侵染能够引发葡萄枝枯病，该研究结果为苗圃中葡萄新芽腐烂坏死防控策略的制定奠定了基础。

盐分会损害大豆的萌发、生长和产量。萌发期是大豆生长发育的关键时期。野生大豆中含有许多抗性基因，是大豆遗传改良的宝贵资源。为了确定野生大豆在盐胁迫下种子萌发期间激活的遗传位点，本研究对两个群体的3个耐盐相关性状进行了筛选，其中一个是包含142个家系的大豆种间杂交群体，另一个是包含121份野生大豆材料的自然群体。利用3个耐盐指标的单核苷酸多态性（SNP）标记，在两个环境下通过连锁定位和全基因组关联研究(GWAS)检测到25个数量性状位点(QTLs)，21个显著SNPs [-Log10(P)≥4.0]和24个潜在SNPs [3.5<-Log10(P)<4.0]。根据这些SNPs和QTLs鉴定出关键遗传区域。根据W05基因组的基因功能注释和盐诱导基因表达实时荧光定量PCR分析，选择GsAKR1作为野生大豆萌发阶段响应盐胁迫的候选基因。这些结果有助于确定野生大豆耐盐遗传网络，并为耐盐大豆的分子标记辅助选择提供依据。

2009年在中国首次发现了柑橘褪绿矮缩病毒（CCDaV），该病毒在云南瑞丽造成柠檬大量发病、减产，损失严重。目前，CCDaV在中国其它柑橘种植省份的发生分布和流行趋势尚不清楚。为了系统掌握CCDaV在中国的发生分布及其分子特性，本研究于2017-2019年，从中国11个柑橘主要生产省份采集了1,772份柑橘样品，通过PCR检测发现，采自广西省、云南省和广东省的134份柑橘样品感染了CCDaV。其中感病品种分别为红宝石蜜柚（50.8%）、泰国青柚（24.0%）、尤力克柠檬（20.8%）、墨西哥莱檬（20.0%）、塔希提莱檬（18.2%）和三红蜜柚（3.2%）。在采集的甜橙、宽皮柑橘、杂柑、枳、葡萄柚和金柑等柑橘类型样品中均没有检测出CCDaV。与前期的研究结果相比，CCDaV在中国的发生区域正在逐步扩大，且感病品种的种类也在增加。此外，CCDaV在红宝石蜜柚、泰国青柚和三红蜜柚新梢上产生的症状较其在尤力克柠檬上更为严重，除产生典型的“V”型叶，叶片扭曲、畸形，黄化外，CCDaV在上述3种柚类品种上还能产生严重的脉明症状。本研究选取了17个CCDaV毒株与GenBank数据库中已知的15个CCDaV毒株进行全系列分析，结果显示CCDaV的序列保守性高，所有 32个CCDaV毒株的核苷酸相似性大约为99%-100%。系统发育树分析表明，CCDaV毒株间的亲缘关系与其采样地和寄主存在相关性。根据地理来源和寄主种类的差异，CCDaV毒株被划分成了4个不同的类群，其中中国和土耳其的CCDaV毒株属于不同的类群。此外，还首次证明中国的CCDaV毒株可能存在多个起源中心，且部分毒株可能来自泰国。本研究结果为明确CCDaV在中国的发生分布、流行规律，以及遗传演化提供了重要的理论依据。

The concentration of soil Olsen-P is rapidly increasing in many parts of China, where P budget (P input minus P output) is the main factor influencing soil Olsen-P.  Understanding the relationship between soil Olsen-P and P budget is useful in estimating soil Olsen-P content and conducting P management strategies.  To address this, a long-term experiment (1991–2011) was performed on a fluvo-aquic soil in Beijing, China, where seven fertilization treatments were used to study the response of soil Olsen-P to P budget.  The results showed that the relationship between the decrease in soil Olsen-P and P deficit could be simulated by a simple linear model.  In treatments without P fertilization (CK, N, and NK), soil Olsen-P decreased by 2.4, 1.9, and 1.4 mg kg^–1 for every 100 kg ha^–1 of P deficit, respectively.  Under conditions of P addition, the relationship between the increase in soil Olsen-P and P surplus could be divided into two stages.  When P surplus was lower than the range of 729–884 kg ha^–1, soil Olsen-P fluctuated over the course of the experimental period with chemical fertilizers (NP and NPK), and increased by 5.0 and 2.0 mg kg^–1, respectively, when treated with chemical fertilizers combined with manure (NPKM and 1.5NPKM) for every 100 kg ha^–1 of P surplus.  When P surplus was higher than the range of 729–884 kg ha^–1, soil Olsen-P increased by 49.0 and 37.0 mg kg^–1 in NPKM and 1.5NPKM treatments, respectively, for every 100 kg ha^–1 P surplus.  The relationship between the increase in soil Olsen-P and P surplus could be simulated by two-segment linear models.  The cumulative P budget at the turning point was defined as the “storage threshold” of a fluvo-aquic soil in Beijing, and the storage thresholds under NPKM and 1.5NPKM were 729 and 884 kg ha^–1 P for more adsorption sites.  According to the critical soil P values (CPVs) and the relationship between soil Olsen-P and P budget, the quantity of P fertilizers for winter wheat could be increased and that of summer maize could be decreased based on the results of treatments in chemical fertilization.  Additionally, when chemical fertilizers are combined with manures (NPKM and 1.5NPKM), it could take approximately 9–11 years for soil Olsen-P to decrease to the critical soil P values of crops grown in the absence of P fertilizer. 

Global demand for soil data and information for maintaining and improving agricultural productivity and environmental health is soaring.  The accurate and rapid digital maps of soil characteristics are of key importance for evaluation of soil fertility, precision management of crop inputs, estimation of carbon stocks, and modeling ecological responses as well as environmental threats.  

The progress in digital soil mapping (DSM) over the last decade provided an improved choice to monitor and map soil characteristics in space and time.  Previous reviews have discussed the history (McBratney et al. 2003; Hartemink et al. 2013; Minasny and McBratney 2016) and the progress in DSM in general (Grunwald et al. 2011; Zhang et al. 2017).  However, the field of DSM has been moving at an accelerated pace and the progress has been observed in all aspects including data organization and quality, soil sampling, environmental covariates, predictive models, and map validation.  In this special issue, the selected eight papers document some of the scopes, developments and progresses in digital mapping in agriculture and environment.

First four papers documented the progress and developments in predictive models.  Teng et al. (2019) used new methodologies including Collocated CoKriging (ColCOK), geographically weighted regression (GWR) and Random Forest (RF) regression to integrate satellite images, field samples, and ground observations to map the soil loss potential in China.  Cheng et al. (2019) proposed a method of mining soil–environmental relationships from individual soil polygons to update conventional soil maps of the Raffelson watershed in La Crosse County, Wisconsin, United States.  Gao et al. (2019) predicted the spatial variability of soil total nitrogen (TN), total phosphorus (TP) and total potassium (TK) using geostatistical analysis and regression analysis.  Li et al. (2019) evaluated the spatial variability of soil bulk density and its controlling factors at different soil layers in Southwest China’s agricultural intensive area.

The following three papers documented the progress in environmental covariate selection, processing and utilization.  Lu et al. (2019) proposed a framework integrating Pearson correlation analysis, generalized additive models (GAMs), and Random Forest (RF) to select environmental covariates for predictive soil depth mapping in the upper reaches of the Heihe River Basin in Northwest China.  Wu et al. (2019) used the combination of surface albedo computed from moderate resolution imaging spectroradiometer (MODIS) reflectance products and the actual measured soil moisture data to map an albedo/vegetation coverage trapezoid feature space.  Wang et al. (2019) applied natural language processing (NLP) and rule-based techniques to automatically extract and structure information from soil survey reports regarding soil–environment relationships.

The last paper talked about soil sampling.  Guo et al. (2019) employed EM38 data to estimate the spatio-temporal variation of soil salinity in different site-specific management zones.  Fuzzy-k means algorithm was used to divide the site-specific management zones and to help sampling design.  

We believe that the reader both in China and abroad will be interested in these articles and be inspired with the finding of the papers for developing future research on digital mapping in agriculture and environment.  We want to express our deepest appreciation to all the authors for their high-quality contributions and efforts to make this special issue a great success.

Received  14 August, 2017    Accepted  20 December, 2017

 

Rapeseed is a very important oil crop in China; however, its production is challenging due to the absence of effective weed management strategies.  This is predominantly because of a shortage of herbicide resistance genes.  Acetohydroxyacid synthase (AHAS) herbicides inhibit AHAS, a key enzyme involved in branched-chain amino acid synthesis that is required for plant growth.  A rapeseed line designated M342 with AHAS herbicide resistance was developed through seed mutagenesis and was studied to assess the level and mode of inheritance of the resistance and to identify the molecular basis of resistance.  M342 possessed a high level of cross-resistance to sulfonylureas (SUs) and imidazolinones (IMIs).  This resistance was due to AHAS insensitivity to these herbicides and was inherited as a dominant trait conferred by a single nuclear-encoded gene.  Molecular analysis revealed the presence of a Trp574Leu mutation in M342, and an allele-specific cleaved amplified polymorphic sequence (AS-CAPS) marker was developed and cosegregated with herbicide resistance in the F₂, BC₁, and BC₂ populations.  This mutation altered the transcript levels of BnAHAS1 and BnAHAS3 in M342 compared with those in the wild type, but it did not affect the agronomic or quality traits.  The simple genetic inheritance of this mutation and the availability of the cleaved amplified polymorphic sequence (CAPS) marker and herbicide resistance gene should facilitate the development of herbicide-resistant rapeseed cultivars for effective weed control in China.  

A total of 900 one-d-old Chinese Huainan Partridge Shank chickens were randomly allocated into nine groups with five replicates of 20 each.  Birds were fed with basal diet, basal diet supplemented with 150 mg kg^–1 aureomycin, basal diet supplemented with different proportions of Bacillus licheniformis and Bacillus subtilis, which was 0:1.0×10⁶, 2.5×10⁵:7.5×10⁵, 3.3×10⁵:6.6×10⁵, 5.0×10⁵:5.0×10⁵, 6.6×10⁵:3.3×10⁵, 7.5×10⁵:2.5×10⁵ and 1.0×10⁶:0, respectively.  The duration of the experiment was 56 d.  The results indicated that dietary supplementation of 6.6×10⁵:3.3×10⁵ of B. lichenifornis:B. subtilis improved final body weight, increased the average daily gain, and reduced feed/gain ratio (P<0.05).  The numbers of total Lactobacillus and Bifidobacterium sp. in the caecum significantly increased, and the numbers of Escherichia coli and Salmonella sp. significantly declined compared to that of the control (P<0.05).  Intestinal villous height and villous height to crypt depth ratio of the duodenum, jejunum, and ileum were significantly higher than that of the control, and intestinal crypt depth of the duodenum and ileum was significantly lower (P<0.05).  The total antioxidant capacity, total superoxide dismutase, and glutathione peroxidase ability in plasma significantly improved, while the malondialdehyde concentration in plasma decreased (P<0.05).  Compared to the control, plasma concentrations of ammonia, uric acid and urea nitrogen and the activity of xanthine oxidase were reduced (P<0.05).  In conclusion, an inclusion of 6.6×10⁵:3.3×10⁵ of B. licheniformis: B. subtilis to the diet improved the growth performance, caecal microbiota, plasma biochemical profile, and significantly improved the small intestine morphology, while reducing the mortality rate. 

The additions of straw and biochar have been suggested to increase soil fertility, carbon sequestration, and crop productivity of agricultural lands.  To our knowledge, there is little information on the effects of straw and biochar addition on soil nitrogen form, carbon storage, and super rice yield in cold waterlogged paddy soils.  We performed field trials with four treatments including conventional fertilization system (CK), straw amendment 6 t ha^–1 (S), biochar amendment 2 t ha^–1 (C1), and biochar amendment 40 t ha^–1 (C2).  The super japonica rice variety, Shennong 265, was selected as the test crop.  The results showed that the straw and biochar amendments improved total nitrogen and organic carbon content of the soil, reduced N₂O emissions, and had little influence on nitrogen retention, nitrogen density, and CO₂ emissions.  The S and C1 increased NH₄⁺-N content, and C2 increased NO₃^–-N content.  Both S and C1 had little influence on soil organic carbon density (SOCD) and C/N ratio.  However, C2 greatly increased SOCD and C/N ratio.  C1 and C2 significantly improved the soil carbon sequestration (SCS) by 62.9 and 214.0% (P<0.05), respectively, while S had no influence on SCS.  C1 and C2 maintained the stability of super rice yield, and significantly reduced CH₄ emissions, global warming potential (GWP), and greenhouse gas intensity (GHGI), whereas S had the opposite and negative effects.  In summary, the biochar amendments in cold waterlogged paddy soils of North China increased soil nitrogen and carbon content, improved soil carbon sequestration, and reduced GHG emission without affecting the yield of super rice.

   The proline transporter protein (ProT) plays an important role in protective stress responses in various plants. However, its function in abiotic stress responses in soybean (Glycine max) remains obscure. In the present study, two soybean ProT genes, namely GmProT1 and GmProT2, were isolated by homologous cloning. GmProT1 and GmProT2 encode polypeptides of 435 and 433 amino acids, respectively. The GmProT1 and GmProT2 proteins showed high similarity to other ProT proteins. GmProT1 and GmProT2 transcripts were detected in different soybean tissues including roots, stems, leaves, flowers, and developmental seeds, and during diverse developmental stages. GmProT1 was strongly expressed in seeds 35 days after flowering. Quantitative real-time PCR analysis showed that the two genes were highly expressed in leaves and could be strongly induced in response to salt and drought conditions and ABA treatment. Transgenic Arabidopsis thaliana plants overexpressing the two genes were generated, which showed that GmProT genes attenuate damage from salt and drought stress. In addition, transgenic Arabidopsis plants accumulated proline in response to salt and osmotic stress. Transcription levels of salinity-responsive gene (RD29B and S0S3) and drought-induced gene (CDPK1) were higher in the transgenic lines than that of wild type plants. Our work provides evidence that GmProT genes function in the response to abiotic stresses and may affect the synthesis and response system of proline.

China is the largest potato producing country worldwide, with this crop representing the fourth largest staple food crop in China. However, the steady presence of Potato spindle tuber viroid (PSTVd) over the past five decades has a significant economic impact on potato production. To determine why PSTVd control measures have been ineffective in China, more than 1 000 seed potatoes collected between 2009 and 2014 were subjected to PSTVd detection at the Supervision and Testing Center for Virus-free Seed Potatoes Quality, Ministry of Agriculture, China. A high PSTVd infection rate (6.5%) was detected among these commercial seed potatoes. Some breeding lines of potato collected from 2012 to 2015 were also tested for PSTVd infection, revealing a high rate of PSTVd contamination in these potato propagation materials. Furthermore, comparison of the full-length sequences of 71 different Chinese PSTVd isolates revealed a total of 74 predominant PSTVd variants, which represented 42 different sequence variants of PSTVd. Comparative sequence analysis revealed 30 novel PSTVd sequence variants specific to China. Comprehensive phylogenetic analysis uncovered a close relationship between the Chinese PSTVd sequence variants and those isolated from Russia. It is worth noting that three intermediate strains and six mild strains were identified among these variants. These results have important implications for explaining the ineffective control of PSTVd in China and thus could serve as a basic reference for designing more effective measures to eliminate PSTVd from China in the future.

    CD8, a glycoprotein on the surface of T cells, is involved in the defense against viral infection and plays significant roles in antigen presentation and in the antiviral immune response. CD8 is composed of two chains. Of these, the CD8α chain was chosen for the detection because it involved in both the CD8αα homodimer and the CD8αβ heterodimer. Here, we established a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) for specific detection of goose CD8α (goCD8α). The results showed that the optimal coated antibody and antigen dilutions were 1:50 (the antibody titer was 1:12 800) and 1:32 (0.3 ng mL^–1), respectively, while the optimal capture antibody and horseradish peroxidase (HRP)-labelled goat anti-rabbit IgG dilutions were 1:50 (the antibody titer was 1:51 200) and 1:4 000 (the antibody titer was 1:5 000), respectively. The optimal blocking buffer was 5% bovine serum albumin (BSA). The best incubating condition was overnight at 4°C, the best blocking time was 120 min and the best anti-capture antibody working time was 150 min. In addition, the minimum dose detectable by DAS-ELISA was 5×10–3 ng mL^–1. Most importantly, goCD8α expression levels in goose spleen mononuclear cells (MNCs) post-Goose parvoviruse (GPV) infection were found to be significantly up-regulated using the DAS-ELISA method, which was consistent with previous results obtained using real-time quantitative PCR. In conclusion, the DAS-ELISA method reported here is a novel, specific technique for the clinical detection of goCD8α.

The SQUAMOSA promoter binding protein (SBP)-box genes encode a kind of plant-specific transcription factors (TFs) and play important roles in the regulation of plant development. In this study, a genome-wide characterization of this family was conducted in maize (Zea mays). Thirty-one SBP-box genes were identified to be distributed in nine chromosomes and 16 of them were complementary to the mature ZmmiR156 sequences. All the Z. mays SBP (ZmSBP) genes were classified into two clusters with eight subgroups according to the phylogenetic analysis of proteins, which were consistent with the pattern of exon-intron structures. The phylogenetic tree of the ZmSBP, Oryza sativa SBP-like (OsSPL) and Arabidopsis thaliana SBP-like (AtSPL) genes were constructed and all the SBP-box genes were divided into eight groups, which was the same as the classification of ZmSBP genes. The comparision of the expression profiles of all SBP-box genes in these three species indicated that most orthologous genes had similar expression patterns. The results from this study provided a basic understanding of the ZmSBP genes and might facilitate future researches for elucidating the SBP-box genes function in maize.

Increasing attentions have been paid to mineral concentration decrease in milled rice grains caused by CO2 enrichment, but the mechanisms still remain unclear. Therefore, mineral (Ca, Mg, Fe, Zn and Mn) translocation in plant-soil system with a FACE (Free-air CO2 enrichment) experiment were investigated in Eastern China after 4-yr operation. Results mainly showed that: (1) elevated CO2 significantly increased the biomass of stem and panicle by 21.9 and 24.0%, respectively, but did not affect the leaf biomass. (2) Elevated CO2 significantly increased the contents of Ca, Mg, Fe, Zn, and Mn in panicle by 61.2, 28.9, 87.0, 36.7, and 66.0%, respectively, and in stem by 13.2, 21.3, 47.2, 91.8, and 25.2%, respectively, but did not affect them in leaf. (3) Elevated CO2 had positive effects on the weight ratio of mineral/biomass in stem and panicle. Our results suggest that elevated CO2 can favor the translocation of Ca, Mg, Fe, Zn, and Mn from soil to stem and panicle. The CO2-led mineral decline in milled rice grains may mainly attribute to the CO2-led unbalanced stimulations on the translocations of minerals and carbohydrates from vegetative parts (e.g., leaf, stem, branch and husk) to the grains.

The regeneration rate of wheat immature embryo varies among genotypes, howbeit many elite agriculture wheat varieties have low regeneration rates. Optimization of tissue culture conditions and attempts of adding signal molecules are effective ways to increase plant regeneration rate. Inter-culture is one of ways that have not been investigated in plant tissue culture. Moreover, the use of arabinogalactan proteins (AGPs) and hydrogen peroxide (H2O2) have been reported to increase regeneration rate in a few plant species other than wheat. The current research pioneeringly uses inter-culture of immature embryos of different wheat genotypes, and also investigates impacts of AGP and H2O2 on the induction of embryogenic calli and plant regeneration. As a result, high-frequency regeneration wheat cultivars Kenong 199 (KN199) and Xinchun 9 (XC9), together with low-frequency regeneration wheat line Chinese Spring (CS), presented striking increase in the induction of embryogenic calli and plant regeneration rate of CS through inter-culture strategy, up to 52.19 and 67.98%, respectively. Adding 50 to 200 mg L–1 AGP or 0.005 to 0.01 ‰ H2O2 to the callus induction medium, enhanced growth of embryogenic calli and plant regeneration rate in quite a few wheat genotypes. At 50 mg L–1 AGP application level in callus induction medium plant regeneration rates of 8.49, 409.06 and 283.16% were achieved for Jimai 22 (JM22), Jingdong 18 (JD18) and Yangmai 18 (YM18), respectively; whereas at 100 mg L–1 AGP level, CS (105.44%), Chuannong 16 (CN16) (80.60%) and Ningchun 4 (NC4) (62.87%) acted the best. Moreover CS (79.05%), JM22 (7.55%), CN16 (101.87%), YM18 (365.56%), Yangmai 20 (YM20) (10.48%), and CB301 (187.40%) were more responsive to 0.005 ‰ of H2O2, and NC4 (35.37%) obtained the highest shoot regeneration rates at 0.01 ‰ of H2O2. Overall, these two methods, inter-culture and AGP (or H2O2) application, can be further applied to wheat transgenic research.

Changes in the soil nematode community induced by global warming may have a considerable influence on agro-ecosystem functioning. However, the impacts of predicted warming on nematode community in farmland (e.g., winter wheat field) have not been well documented. Therefore, a field experiment with free air temperature increase (FATI) was conducted to investigate the responses of the soil nematode community to nighttime warming in a winter wheat field of Yangtze Delta Plain, China, during 2007 to 2009. Nighttime warming (NW) by 1.8°C at 5-cm soil depth had no significant impact on the total nematode abundance compared to un-warmed control (CK). However, NW significantly affected the nematode community structure. Warming favored the bacterivores and fungivores, such as Acrobeles, Monhystera, Rhabditis, and Rhabdontolaimus in bacterivores, and Filenchus in fungivores, while the plant-parasites were hindered, such as Helicotylenchus and Psilenchus. Interestingly, the carnivores/ omnivores remained almost unchanged. Hence, the abundances of bacterivores and fungivores were significantly higher under NW than those under CK. Similarly, the abundances of plant-parasites were significantly lower under NW than under CK. Furthermore, Wasilewska index of the nematode community was significantly higher under NW than those under CK, indicating beneficial effect to the plant in the soil. Our results suggest that nighttime warming may improve soil fertility and decrease soil- borne diseases in winter wheat field through affecting the soil nematode community. It is also indicated that nighttime warming may promote the sustainability of the nematode community by altering genera-specific habitat suitability for soil biota.