与单独供硝（NO₃^-）或者单独供铵（NH₄⁺）相比，混合供氮能够促进苗期玉米的生长。前期研究表明，混合供氮不仅可以提高玉米的光合效率，还可以促进地上部生长素的合成来增强叶片生长，进而为碳和氮的利用构建一个较大的库。然而，该过程是否依赖于氮的吸收还尚不清楚。在此，将玉米幼苗在具有三种供氮形态（单独供硝，75/25硝铵比和单独供铵）的水培实验中进行生长。结果表明，在0-3天，混合供氮下玉米生长速率和地上部含氮量与单独供硝处理间无显著差异，在6-9天，混合供氮下玉米生长速率和地上部含氮量显著高于单独供硝处理。于此同时，虽然混合供氮条件下15NO₃^-与15NH₄⁺的瞬时吸收速率较单独供硝和单独供铵相比皆有所下降，但混合供氮在6-9天具有最高的总氮吸收速率。QRT-PCR结果表明，长期混合供氮条件下根系N吸收的增加可能与长期处理下NO₃^-转运蛋白基因（例如ZmNRT1.1A， ZmNRT1.1B，ZmNRT1.1C， ZmNRT1.2和ZmNRT1.3）的高表达或铵转运蛋白基因（例如ZmAMT1.1A）的高表达有关，尤其是后者。此外，与单独供硝处理相比，混合供氮处理下植株地上部与根系中具有较高的谷氨酰胺合酶（GS）活性以及氨基酸含量。硝酸还原酶酶（NR）和GS酶抑制剂实验进一步证明了混合供氮情况下氮的同化能力对于玉米生长促进是至关重要的。该研究证明了混合供氮能够促进氮素吸收并进一步促进了氮的同化，而该过程可能是促进玉米上生长的主要驱动力。

家畜脊椎数特别是胸腰椎数存在遗传变异，这些变异与家畜体长和产肉量有关。德州驴是我国著名的地方驴种之一，它的特点是体型大，适应性好，抗粗饲。德州驴群体中胸腰椎数也存在变异。【目的】本研究利用低深度重测序填充数据通过全基因组关联分析挖掘调控德州驴胸腰椎数性状相关的分子标记和候选基因，为未来多胸腰椎数驴的新品种培育奠定理论基础。【方法】对347头德州驴群体进行低深度的全基因组重测序，选用STITCH + Beagle的方法进行基因型的填充，对获得的SNPs进行质控后利用GEMMA软件的线性混合模型和GMMAT软件的logistic混合模型对胸腰椎数性状进行关联分析。SNPs数据进行了连锁不平衡过滤（=0.2）最终获得约35万个有效SNPs，用Bonferroni进行多重检验校正，设置了5%全基因组水平显著关联阈值线P ≤ 1.41×10-7（= 0.05/353,672）以及潜在显著关联的水平P ≤ 2.83×10-6（= 1/353,672）。最终对显著关联的SNPs进行候选基因的鉴定和单倍型分析。【结果】347头德州驴群体平均测序深度为4×，基因型填充后最终获得6,220,779 SNPs，利用18头高深度的德州驴群体对填充准确性进行评估，结果显示平均基因型相关系数是0.98。综合两个关联分析的模型，对于胸椎数性状，我们鉴定出38个全基因组水平显著关联的SNPs和64个潜在显著关联的SNPs，涉及7个基因（NLGN1、DCC、SLC26A7、TOX、WNT7A、LOC123286078和LOC123280142）。对于腰椎数性状，我们鉴定了9个全基因组水平显著关联的SNPs和38个潜在显著关联的SNPs，涉及8个基因（GABBR2、FBXO4、LOC123277146、LOC123277359、BMP7、B3GAT1、EML2和LRP5）。其中多个显著关联SNPs存在紧密的连锁不平衡关系。【结论】本研究利用测序填充数据进行全基因组关联分析，鉴定了多个与胸腰椎数性状显著关联的SNPs和候选基因，其中WNT7A、BMP7和LRP5已知的功能是通过Wnt信号通路和TGF-β信号通路在胚胎体节发育和骨形成过程中发挥作用，可能是驴差异胸腰椎数性状的关键候选基因。

本研究以来源于辽宁、吉林和黑龙江三个省份的200个粳稻品种为实验材料，对碾磨和外观品质相关的性状进行考察。材料的系谱分析和遗传多样性分析结果表明，来自吉林省的品种遗传多样性最高。稻米品质的评价结果表明，来自辽宁省的品种具较好的碾磨品质，而来自黑龙江的品种具较好的外观品质。本研究同时用单位点和多位点的全基因组关联分析（GWAS）对碾磨和外观品质相关的基因位点进行计算，结果共检测到99个显著的SNP位点。其中，共3个SNP位点同时在混合线性模型（MLM）、mrMLM和FASTmrMLM这3种计算模型中检测到，进一步利用连锁不平衡分析获得对应的3个候选区域（qBRR-1、qBRR-9和qDEC-3），以便于后续的候选基因分析。由于候选区域内的候选基因超过300个，研究还结合基因GO分析以鉴定潜在的候选基因。此外，候选区域的遗传多样性分析结果表明，qBRR-9很可能在东北粳稻的育种过程中受到了较强的选择。这些结果为水稻育种和品质改良提供了具有参考意义的信息。

籽粒灌浆速率（GFR）在小麦产量形成过程中起着关键作用，但由于表型调查困难等原因，对其遗传解析研究甚少。本研究测定了1个重组自交系群体和1个自然群体籽粒灌浆性状，基于高密度图谱进行相关性状的连锁分析和全基因组关联分析。在染色体 1B、4B和5A上鉴定到17个稳定的QTLs。 其中IWB19555-IWB56078 连锁区间对性状 GFR₁、GFR_max、KL、KW、KT 和TKW具有多效性，表型变异解释率（PVE）为13.38%（KW）- 33.69%（TKW）。检测到198个显著性状关联位点（MTAs）分布在除了3D和4D之外的染色体上。GFR的主要关联位点包括 IWB44469（11.27%）、IWB8156（12.56%）和IWB24812（14.46%）。检测到IWB41019是籽粒大小相关的重要多效性位点。通过GWAS鉴定到的IWB35850与连锁分析获得的QGFR_max2B.3-11位于同一区域，该区域包含两个高置信候选基因。检测到两个重要的粒重相关 QTL与灌浆速率 QTL定位到同一区间。这些发现有助于解析 GFR 的遗传基础，为小麦产量性状 QTL候选基因预测提供理论依据。

基于全国性大规模的2016年度中国家庭追踪调查数据，使用工具变量法的IVProbit模型，本文实证研究了新型农村合作医疗保险对农村居民家庭健康脱贫的影响。研究发现，第一，新型农村合作医疗保险对农村居民家庭健康脱贫的效果显著。家庭成员患病进行住院治疗，增加了该家庭陷入贫困的风险，新型农村合作医疗保险显著降低了中国农村居民家庭陷入贫困的概率。第二，新农合对农村家庭健康脱贫的影响在不同收入人群之间存在显著的差别。新农合对中高收入组和高收入组农村家庭的健康脱贫没有影响，但是显著提高了低收入组、尤其中低收入组的农村家庭，其因病致贫和因病返贫的防范能力。第三，新农合对农村家庭健康脱贫的影响效果存在显著的地区差异。新农合显著降低了西部地区农村居民家庭陷入贫困的风险，对东部和中部地区的农村居民家庭没有影响。为了减少和消除贫困，增强农村居民的收入获取能力，本文建议采取以下措施：切实提高新型农村合作医疗保险的实际补偿比、积极推进新农合的支付方式改革以控制医疗费用增长、加强西部地区的医疗卫生服务综合体系建设、加强边缘贫困人口医疗保障的制度建设，以及加强农村地区的人居健康环境改造。

Carex rigescens (Franch.) V. Krecz is a wild turfgrass perennial species in the Carex genus that is widely distributed in salinised areas of northern China.  To investigate genome-wide salt-response gene networks in C. rigescens, transcriptome analysis using high-throughput RNA sequencing on C. rigescens exposed to a 0.4% salt treatment (Cr_Salt) was compared to a non-salt control (Cr_Ctrl).  In total, 57 742 546 and 47 063 488 clean reads were obtained from the Cr_Ctrl and Cr_Salt treatments, respectively.  Additionally, 21 954 unigenes were found and annotated using multiple databases.  Among these unigenes, 34 were found to respond to salt stress at a statistically significant level with 6 genes up-regulated and 28 down-regulated.  Specifically, genes encoding an EF-hand domain, ZFP and AP2 were responsive to salt stress, highlighting their roles in future research regarding salt tolerance in C. rigescens and other plants.  According to our quantitative RT-PCR results, the expression pattern of all detected differentially expressed genes were consistent with the RNA-seq results.  Furthermore, we identified 11 643 simple sequence repeats (SSRs) from the unigenes.  A total of 144 amplified successfully in the C. rigescens cultivar Lüping 1, and 69 of them reflected polymorphisms between the two genotypes tested.  This is the first genome-wide transcriptome study of C. rigescens in both salt-responsive gene investigation and SSR marker exploration.  Our results provide further insights into genome annotation, novel gene discovery, molecular breeding and comparative genomics in C. rigescens and related grass species.

Alfalfa (Medicago sativa L.) is an important forage crop and is also a target of many fungal diseases including Fusarium spp.  As of today, very little information is available about molecular mechanisms that contribute to pathogenesis and defense responses in alfalfa against Fusarium spp. and specifically against Fusarium proliferatum, the causal agent of alfalfa root rot.  In this study, we used a proteomic approach to identify inducible proteins in alfalfa during a compatible interaction with F. proliferatum strain YQC-L1.  Samples used for the two-dimensional gel electrophoresis (2-DE) and MALDI-TOF/TOF mass spectrometry were from roots and leaves of alfalfa cultivar AmeriGraze 401+Z and WL656HQ.  Plants were grown in hydroponic conditions and at 4 days post inoculation with YQC-L1.  Our disease symptom assays indicated that AmeriGraze 401+Z  was tolerant to YQC-L1 infection while WL656HQ was highly susceptible.  Analysis of differentially expressed proteins found in the 2-DE was further characterized using the MASCOT MS/MS ion search software and associated databases to identify multiple proteins that might be involved in F. proliferatum resistance.  A total of 66 and 27 differentially expressed proteins were found in the roots and leaves of the plants inoculated with YQC-L1, respectively.  These identified proteins were placed in various categories including defense and stress response related metabolism, photosynthesis and protein synthesis.  Thirteen identified proteins were validated for their expressions by quantitative reverse transcription (qRT)-PCR.  Our results suggested that some of the identified proteins might play important roles in alfalfa resistance against Fusarium spp.  These finding could facilitate further dissections of molecular mechanisms controlling root rot disease in alfalfa and potentially other legume crops.   

Creating a crop-heterogeneous system by intraspecific mixtures of different rice varieties can substantially reduce blast diseases. Such variety mixtures provide an ecological approach for effective disease control, maintaining high yields with the minimum fungicide applications. Whether such an approach is universally applicable for random rice variety combinations and what is the variation pattern of the diseases under intercropping still remains unclear. We conducted two-year large-scale field experiments involving 47 rice varieties/lines and 98 variety-combinations to compare the occurrence of rice blast in monoculture and intercropping plots at multiple sites. In the experiments, the plant height of the selected traditional varieties was about 30 cm taller, and their life cycle was 10 days longer, than that of the improved rice varieties. The monoculture included either traditional or modern rice varieties grown in separate plots. The intercropping included both traditional and modern rice varieties planted together in the same plots. Results from the field experiments under natural disease conditions demonstrated significant reduction for rice blast disease in intercropping plots, compared with that in monoculture plots. For traditional varieties, the average blast incidence reduced from ~26% in monoculture to ~10% in intercropping, and the disease severity reduced from ~17 in monoculture to ~5 in intercropping. For modern varieties, the average blast incidence reduced from ~19% in monoculture to ~10% in intercropping, and the severity from ~10 in monoculture to ~4 in intercropping. Traditional rice varieties (~72%) had a much greater increase in the efficiency of disease control than modern varieties (~60%). In addition, substantially lower values of variance in the blast incidence and severity was detected among the variety combinations in intercropping plots than in monoculture plots. Based on these results, we conclude that the intercropping or mixture of rice varieties greatly reduces the occurrence and variation of rice blast disease in particular variety combinations, which makes the intercropping system more stable and consistent for disease suppression on a large scale of rice cultivation.

Methylation of the N6 position of adenine, termed N6-methyladenine, protects DNA from restriction endonucleases via the host-specific restriction-modification system. N6-methyladenine was discovered and has been well studied in bacteria. N6-adenine-specific DNA methyltransferase (N6AMT) is the main enzyme catalyzing the methylation of the adenine base and knowledge of this enzyme was mainly derived from work in prokaryotic models. However, large-scale gene discovery at the genome level in many model organisms indicated that the N6AMT gene also exists in eukaryotes, such as humans, mice, fruit flies and plants. Here, we cloned a N6AMT gene from Nilaparvata lugens (Nlu-N6AMT) and amplified its fulllength transcript. Then, we carried out a systematic investigation of N6AMT in 33 publically available insect genomes, indicating that all studied insects had N6AMT. Genomic structure analysis showed that insect N6AMT has short introns compared with the mammalian homologs. Domain and phylogenetic analysis indicated that insect N6AMT had a conserved N6-adenineMlase domain that is specific to catalyze the adenine methylation. Nlu-N6AMT was highly expressed in the adult female. We knocked down Nlu-N6AMT by feeding dsRNA from the second instar nymph to adult female, inducing retard development of adult female. In all, we provide the first genome-wide analysis of N6AMT in insects and presented the experimental evidence that N6AMT might have important functions in reproductive development and ovary maturation.

    Alfalfa is widely grown and is one of the most important forage crops in the world, but its growth and biomass production are markedly reduced under salt and drought stress, particularly during the early seedling stage. To identify the mechanisms behind salt and drought responsiveness at the alfalfa seedling stage, the proteins expressed were analyzed under no-treatment, 200 mol L^–1 NaCl and 180 g L^–1 PEG treatment conditions during the seedling stage. Out of more than 800 protein spots detected on two-dimensional electrophoresis (2-DE) gels, 35 proteins showed statistically significant responses (P<0.05) to NaCl and PEG stress, which were selected for tandem mass spectrometric identification, owing to their good resolution and abundance levels, and 32 proteins were positively identified. The identified proteins were divided into seven functional categories: photosynthetic metabolism, protein biosynthesis, folding and assembly, carbohydrate metabolism-associated proteins, stress defense related protein, metabolism of nucleic acid, other function categories and unknown proteins. Our results suggested that these proteins may play roles in alfalfa adaptation to salt and drought stress. Further study of these proteins will provide insights into the molecular mechanisms of abiotic stress and the discovery of new candidate markers in alfalfa.

One concern about the use of transgenic plants is their potential risk to natural enemies. In this study, using the eggs of the rice brown planthopper, Nilaparvata lugens, as a food source, we investigated the effects of Cry1Ab rice on the biological characteristics and functional response of an important predator Cyrtorhinus lividipennis. The results showed that the survival ability (adult emergence rate and egg hatching rate), development (egg duration, nymphal developmental duration), adult fresh weight, adult longevity and fecundity of C. lividipennis on Bt rice plants were not significantly different compared to those on non-Bt rice plants. Furthermore, two important parameters of functional response (instantaneous search rate and handling time) were not significantly affected by Bt rice. In conclusion, the tested Cry1Ab rice does not adversely impact the biological character and functional response of C. lividipennis.

Pasteurella multocida, a Gram-negative nonmotile coccobacillus, is the causative agent of fowl cholera, bovine hemorrhagic septicemia, enzoonotic pneumonia and swine atropic rhinitis. Two filamentous hemagglutinin genes, fhaB1 and fhaB2, are the potential virulence factors. In this study, an inactivation fhaB1 mutant of P. multocida in avian strain C48-102 was constructed by a kanamycin-resistance cassette. The virulence of the fhaB1 mutant and the wild type strain was assessed in chickens by intranasal and intramuscular challenge. The inactivation of fhaB1 resulted in a high degree of attenuation when the chickens were challenged intranasally and a lesser degree when challenged intramuscularly. The fhaB1 mutant and the wild type strain were investigated their sensitivity to the antibody-dependent classical complement-mediated killing pathway in 90% convalescent chicken serum. The fhaB1 mutant was serum sensitive as the viability has reduced between untreated serum and heat inactivated chicken serum (P<0.007). These results confirmed that FhaB1 played the critical roles in the bacterial pathogenesis and further studies were needed to investigate the mechanism which caused reduced virulence of the fhaB1 mutant.