厘清大豆种质籽粒中的类胡萝卜素组分和含量对大豆种质营养品质评价具有重要意义。本研究针对遗传多样性丰富的中国大豆种质的类胡萝卜素和叶绿素含量进行了系统分析，并揭示了不同营养品质组分间的相关性。结果显示基因型、种植年份、种质类型、子叶色和生态区来源显著影响籽粒中类胡萝卜素和叶绿素含量，其平均类胡萝卜素总含量变化范围为8.15-14.72 µg g^-1。大豆农家种的类胡萝卜素含量是栽培种的1.2倍，特别是绿子叶种质的类胡萝卜素和叶绿素含量显著高于黄子叶种质。需要指出的是单一组分中叶黄素的含量是最高的，其变化范围为1.35-37.44 µg g^-1。类胡萝卜素和叶绿素含量与其他品质组分显著相关，这有利于育种者在强化类胡萝卜素含量同时而不影响其他品质组分。我们结果证明了大豆籽粒中的类胡萝卜素含量是丰富的，但其积累宜受遗传因素、种质类型和种质来源的显著影响。我们还鉴定了一批高类胡萝卜素含量的大豆新种质，可以为大豆育种、食品加工和化妆品行业利用。

本研究旨在研究不同中性洗涤纤维/非纤维碳水化合物（NDF/NFC）比例的日粮对不同泌乳阶段荷斯坦奶牛生产性能、养分消化率和CH₄排放的影响，建立日粮结构和产奶量与CH₄的模型，并将该模型与其他已发表的预测模型进行了对比分析。试验将36头泌乳奶牛分为三个处理组，即NDF/NFC=1.19（低NDF/NFC组）、NDF/NFC=1.54（中NDF/NFC处理组）和NDF/NFC=1.68（高NDF/NFC处理组）。使用六氟化硫示踪法测定瘤胃CH₄排放量，酸不溶性灰分法测定营养物质消化率。结果表明，泌乳早期、中期和晚期奶牛随着日粮NDF/NFC比例的增加，干物质采食量（DMI）均显著降低（P<0.01），分别从20.9 降至15.4 kg d^-1，从15.3降至11.6 kg d^-1，从16.4降至15.0 kg d^-1。三种处理中，泌乳中期和后期奶牛的DM和总能(GE)消化率最高(P<0.05)。随着日粮中NDF/NFC比例的增加，泌乳早期、中期和晚期奶牛CH₄排放量呈现线性增加(P<0.05)，分别从325.2到391.9 kg d^-1，261.0到399.8 kg d^-1，241.8到390.6 kg d^-1。每单位代谢体重、DM摄入量、NDF摄入量或脂肪校正产奶量下的CH₄排放量随着日粮中NDF/NFC比例的增加而增加。此外，泌乳早期、中期和晚期奶牛随着日粮NDF/NFC比例的增加，CH₄能占摄入GE的比例显著增加（P<0.05），分别从4.87%到8.12%，5.16%到9.25%，5.06%到8.17%。建立的模型结果表明，使用DM摄入量作为单一变量的方程比使用其他饲粮或产奶量变量的方程产生更大的R²值。将每个泌乳阶段获得的数据合并后，与任何其他预测变量相比，DM摄入量仍然是更好的CH₄排放量预测指标（R²=0.786，P=0.026）。与本文开发的预测方程相比，先前公布的方程具有更高水平的均方根预测误差，反映它们无法准确预测中国荷斯坦奶牛的CH₄排放水平。中国饲养模式下的泌乳奶牛CH₄产量的量化以及相关预测方程的建立，将有助于建立区域或国家的CH₄排放清单和改进乳制品生产过程中的CH₄减排方法。

夏玉米品种及其种植密度是影响玉米抗倒伏能力的主要因素。本试验从木质素代谢的角度来探究不同玉米品种的抗倒伏能力及其种植密度调控。研究结果表明，抗倒伏夏玉米品种登海605 （DH605）具有较低的重心和良好的茎秆形态特征，这是其抗倒伏能力显著高于浚单20（XD20）的原因之一。DH605的木质素积累量、木质素合成途径关键酶活性以及G、S和H型木质素单体含量均显著高于XD20。随着种植密度的增加，两种品种的茎秆机械强度、木质素积累量和木质素合成途径关键酶活性均显著降低，G型木质素单体含量呈现先减少后保持稳定的趋势，S型木质素单体含量呈下降趋势，H木质素型单体含量呈上升趋势。相关性分析表明，倒伏率与植株性状及木质素代谢显著相关。因此，抗倒伏能力强的玉米具有木质素积累量高、木质素合成途径关键酶活性高、S型单体含量高、重心低、茎穿刺强度高、皮质厚度高、维管束面积小等特点，同时，高种植密度降低了茎秆木质素的积累、酶活性和机械强度，进而导致倒伏率提高。

Received  8 September, 2017    Accepted  13 March, 2018

The red flour beetle, Tribolium castaneum, is a major agriculture pest of stored grain, cereal products and peanuts for human consumption.  It is reported that heat shock protein 18.3 of T. castaneum (Tchsp18.3) plays a significant role in stress resistance, development and reproduction.  However, the regulatory systems of Tchsp18.3 remain unknown.  Therefore, we compared the global transcriptome profiles of RNA interference (RNAi)-treated larvae (ds-Tchsp18.3) and control larvae of T. castaneum using RNA sequencing.  Overall, we obtained 14 154 435 sequence reads aligned with 13 299 genes.  Additionally, 569 differentially expressed genes (DEGs) were identified from the ds-Tchsp18.3 and control groups, of which 246 DEGs were annotated in the 47 Gene Ontology (GO) functional groups and 282 DEGs were assigned to 147 Kyoto Encyclopedia of Genes and Genomes (KEGG) biological signaling pathways.  The DEGs encoding viperin, dorsal, Hdd11, PGRP2, defensin1 and defensin2 were simultaneously related to immunity and stress responses, which suggests that cross-talk might exist between the immunity and stress responses of T. castaneum.  The knockdown of Tchsp18.3gene expression suppressed the antioxidant activity process, which most likely modulated the effects of Tchsp18.3 on development and reproduction.  Furthermore, the DEGs, including Blimp-1, Gld, Drm, Kinesin-14, Pthr2, Delta(11)-like and EGF-like domain protein 2, were also associated with the development and reproduction of ds-Tchsp18.3 insects.  Additionally, knockdown of Tchsp18.3 amplified the serine protease (SP) signaling pathway to further regulate stress responses and innate immunity as well as development and reproduction of the red flour beetles.  These results provide valuable insight into the molecular regulatory mechanism of Tchsp18.3 involved in insect physiology and further facilitate the research of suitable and sustainable management for pest control.

The effects of antibacterial compounds produced by Saccharomyces cerevisiae in Koumiss on pathogenic Escherichia coli O₈ and its cell surface characteristics were investigated.  S. cerevisiae isolated from Koumiss produced antibacterial compounds which were active against pathogenic E. coli O₈ as determined by the Oxford cup method.  The aqueous phases from S. cerevisiae at pH=2.0 (S2) and pH=8.0 (S8) were extracted and tested, respectively.  The organic acids of S2 and S8 were determined by high performance liquid chromatography (HPLC), and the concentrations of killer toxins were determined by enhanced bicinchoninic acid (BCA) Protein Assay Kit.  The minimum inhibition concentration (MIC) and the minimum bactericidal concentration (MBC) of S2 and S8 on E. coli O₈ were determined by the broth microdilution method.  The effects of S2 and S8 on the growth curve of E. coli O₈ were determined by turbidimetry, and the hydrophobicities of E. coli O₈ cell surface were determined using the microbial adhesion to solvents method, the permeation of E. coli O₈ cell membrane were determined by the o-nitrophenyl-β-D-galactoside (ONPG) method.  Aqueous phases at pH 2.0 and 8.0 had larger inhibition zones and then S2 and S8 were obtained by freeze-drying.  The main component in S2 was citric acid and it was propanoic acid in S8.  Other organic acids and killer toxins were also present.  Both the MICs of S2 and S8 on E. coli O₈ were 0.025 g mL^–1, the MBCs were 0.100 and 0.200 g mL^–1, respectively.  The normal growth curve of E. coli O₈ was S-shaped, however, it changed after addition of S2 and S8.  E. coli O₈ was the basic character, and had a relatively hydrophilic surface.  The hydrophobicity of E. coli O₈ cell surface and the permeation of E. coli O₈ cell membrane were increased after adding S2 and S8.  The present study showed that S2 and S8 inhibit the growth of pathogenic E. coli O₈ and influence its cell surface characteristics.

Wheat (Triticum aestivum L.) often experiences photoinhibition due to strong light during the grain filling stage. As such, increasing the tolerance of wheat to photoinhibition is very desirable in breeding efforts focused on increasing grain yields. Previous reports have suggested that PROTON GRADIENT REGULATION 5 (PGR5) plays a central role in the generation of a proton gradient across the thylakoid membrane (DpH) and in acclimation to high light intensity conditions. Three PGR5 homoeologues were isolated from wheat, and mapped onto chromosomes 7A, 7B and 7D, respectively. The TaPGR5s shared highly similar genomic sequences and gene structures. The transcripts of TaPGR5s were found to be abundantly expressed in the flag leaves, and were transiently up-regulated by treatment with high light. High light treatment inhibited the net photosynthetic rate (Pn) and the maximal quantum yield of photosystem II (Fv/Fm). Further, these inhibitions were more evident in the leaves with reduced expression of TaPGR5s achieved using virus-induced gene silencing methods. Moreover, reducing TaPGR5 expression impaired the induction of non-photochemical quenching (NPQ), which caused more severe cell membrane damage and lipid peroxidation in high light. Additionally, we observed that TaPGR5s transcripts were more abundantly expressed in the wheat genotypes with higher ms-delayed light emission (ms-DLE), a value reflecting transthylakoid DpH. These results suggested that TaPGR5s play important roles in the tolerance of wheat to photoinhibition.

Soybean cyst nematode (SCN) is one of the most devastating pathogen for soybean. Therefore, identification of resistant germplasm resources and resistant genes is needed to improve SCN resistance for soybean. Soybean varieties Huipizhiheidou and Wuzhaiheidou were distributed in China and exhibited broad spectrums of resistance to various SCN races. In this study, these two resistant varieties, combined with standard susceptible varieties (Lee and Essex), were utilized to identify the differentially expressed transcripts after infection with SCN race 4 between resistant and susceptible reactions by using the Affymetrix Soybean Genome GeneChip. Comparative analyses indicated that 21 common genes changed significantly in the resistant group, of which 16 increased and 5 decreased. However, 12 common genes changed significantly in the susceptible group, of which 9 increased and 3 decreased. Additionally, 27 genes were found in common between resistant and susceptible reactions. The 21 significantly changed genes in resistant reaction were associated with disease and defense, cell structure, transcription, metabolism, and signal transduction. The fold induction of 4 from the 21 genes was confirmed by quantitative RT-PCR (qRTPCR) analysis. Moreover, the gene ontology (GO) enrichment analyses demonstrated the serine family amino acid metabolic process and arginine metabolic process may play important roles in SCN resistance. This study provided a new insight on the genetic basis of soybean resistance to SCN race 4, and the identified resistant or resistant-related genes are potentially useful for SCN-resistance breeding in soybean.

Horizontal gene transfer (HGT) plays key roles in the evolution of pathogenetic bacteria, especially in pathogenetic associated genes. In this study, the evolutionary dynamics of Xanthomonas at species level were determined by the comparative analysis of the complete genomes of 15 Xanthomonas strains. A concatenated multiprotein phyletic pattern and a dataset with Xanthomonas clusters of orthologous genes were constructed. Mathematical extrapolation estimates that the core genome will reach a minimum of about 1 547 genes while the pan-genome will increase up to 22 624 genes when sequencing 1 000 genomes. The HGT extent in this genus was assessed by using a Markov-based probabilistic method. The reconstructed gene gain/loss history, which contained several features consistent with biological observations, showed that nearly 60% of the Xanthomonas genes were acquired by HGT. A large fraction of variability was in the clade ancestor nodes and “leaves of the tree”. Coexpression analysis suggested that the pathogenic and metabolic variation between Xanthomonas oryzae pv. oryzicola and Xanthomonas oryzae pv. oryzae might due to recently-transferred genes. Our results strongly supported that the gene gain/loss may play an important role in divergence and pathogenicity variation of Xanthomonas species.