盐胁迫是一种典型的非生物胁迫，导致植物生长缓慢、发育迟缓、产量和果实品质下降。施肥是保证作物正常生长的必要措施，其中，氮素更是关键元素。研究报道氮肥施加可提高作物耐盐性，但是，氮肥对葡萄耐盐性的影响尚不清楚。因此，本研究以酿酒葡萄幼苗‘黑比诺’为植物材料，研究200 mmol L^-1NaCl处理下施用0.01和0.1 mol L^-1 硝酸铵（N）对葡萄耐盐性的影响。通过对葡萄幼苗叶片的生理指标、转录组和代谢组分析，发现0.01 mol L^-1的N施加显著降低了盐胁迫下葡萄叶片中超氧阴离子（O₂^.-）的积累，提高了超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性，促进了抗坏血酸（AsA）和谷胱甘肽（GSH）的积累。转录组和代谢组的联合分析表明，黄酮生物合成途径（ko00941）和黄酮和黄酮醇生物合成途径（ko00944）是关键的响应通路。进一步发现，槲皮素（C00389）的积累受到盐和氮的显著调节。同时，筛选到10个关键差异基因与槲皮素含量变化高度相关（R²>0.9）并构成互作网络。此外，我们也发现，盐胁迫下叶面喷施槲皮素可提高葡萄的SOD和POD活性，增加AsA和GSH的含量，降低H₂O₂和O₂^.-的含量。因此，本研究应用氮肥和槲皮素改善了葡萄的耐盐性，并鉴定到关键的响应基因，此结果为葡萄耐盐性的提高和分子机制研究提供了新的思路。

以不同年份再植桃园根系土壤为材料，探究再植桃园微生物群落结构的变化情况，并进一步揭示不同年份的再植桃园微生物群落和土壤养分之间的关系，以期为桃树再植病调控提供理论依据。分别收集非再植（NRS）和再植（RS）(再植1年RS1、再植3年RS3、再植5年RS5、再植7年RS7、再植9年RS9、再植11年RS11)桃园桃树的根际土壤，利用高通量测序技术测定土壤细菌和真菌群落的多样性，同时采用RDA分析土壤微生物群落与土壤环境因子之间的关系。结果显示，RS早期（1-5年）的土壤养分含量低于NRS，但随着桃树种植年限的增加，它们之间的差异逐渐缩小，直至达到相近的水平。细菌和真菌群落的alpha多样性指数表明，RS比NRS含有更高丰度的细菌和真菌OUT含量。NMDS和ANOSIM分析表明，土壤细菌和真菌群落显著受种植年限影响（p<0.01），其变化主要发生在种植1年和9年。从目的分类水平看，再植桃园土壤中，Sphingobacteriales, Burkholderiales 和 Actinomycetales显著发生变化。一些与生物修复相关的细菌，如Burkholderiales目 和 Intrasporangiaceae纲，以及一些有害的病原真菌，如Penicillium属 和 Ophiostomatales纲,在再植桃园中显着增加（LDA> 3.0）。此外， RDA结果表明微生物群落的组成与环境各因子（pH、AP、AN 和 AK）间存在密切相关。从细菌门的分类水平看，这些环境变量与Acidobacteria, Chloroflexi, 和 Actinobacteria呈正相关，与Proteobacteria 和 Firmicutes呈负相关。在真菌门水平中，Basidiomycota门在 pH、AP 和 AN 增加的环境中增强，而Ascomycota, Chytridiomycota 和 Zygomycota门与 AK 呈正相关。RS的细菌和真菌群落多样性高于NRS，桃树再植病害的发生与土壤微生物群落的变化密切相关。我们的研究结果详细阐明了不同年份的 NRS 和 RS微生物群落的变化情况以及两者之间土壤理化和微生物群落变化之间的关系。这些结果使人们更加深入的了解再植桃园微生物群落的变化，为桃树再植病的解决提供思路。

由于玉米植株的结构特征对其冠层的资源利用和对风雨等因素造成的倒伏的忍耐能力以及产量的稳定性具有重要影响，因此受到广泛关注。量化自交系之间的形态多样性对于杂交育种至关重要，尤其在描述大量的种质资源时。然而，传统的几何描述方法过于简化植株结构并忽略了植株整体结构特征，因此难以反映和展示植株结构的多样性。本文介绍了一种新的描述玉米植株结构并量化其多样性的方法，该方法结合了计算机视觉算法和数学的持续同调理论。结果表明，持续同调方法可以捕捉玉米植株结构的关键特征和其他通常被传统几何分析方法所忽略的细节。基于这种方法，可以挖掘（量化）植株结构的形态多样性，并分析玉米植株结构的主要类型。

提高小麦产量是全球小麦育种者的长期目标。发掘优良遗传资源，解析小麦重要农艺性状的遗传基础，是小麦高产育种的必经之路。本研究评价了两年七个环境中由156个育成品种和77个地方品种组成的四川小麦自然群体的9个重要农艺性状表现。农艺性状调查结果表明，地方品种分蘖较多，穗粒数（KNS）较高，育成品种千粒重（TKW）和穗粒重（KWS）较高。9个农艺性状的广义遗传力（H ²）在0.74到0.95之间。利用来自小麦55K SNP芯片的43198个单核苷酸多态性（SNP）标记进行群体结构分析可以将自然群体分为三组。基于混合线性模型Q+K方法的全基因组关联分析（GWAS）共鉴定出67个数量性状位点（QTL）。本研究主要对三个重要性状的QTL进行了分析，即分别检测到的可育分蘖数（FTN）位点QFTN.sicau-7BL.1的四种单倍型、KNS位点QKNS.sicau-1AL.2的三种单倍型和TKW位点QTKW.sicau-3BS.1的四种单倍型。从2002—2013年区域试验的42个品种的产量表现来看，FTN-Hap2、KNS-Hap1和TKW-Hap2分别是每个QTL中的优良单倍型。具有三个优良单倍型的品种相比具有两个或一个优良单倍型的品种产量更高。此外，基于每穗粒数的QTL位点 QKNS.sicau-1AL.2开发了连锁的KASP-AX-108866053标记能在2018年至2021年区域试验中鉴定63个品种的三种单倍型（或等位基因）。这些遗传位点和连锁标记可用于标记辅助选择或基于图谱的基因克隆，用于小麦产量的遗传改良。

本研究以41个代表性的玉米自交系通过不完全双列杂交产生了737个杂种F1的多杂种群体（MPH），将MPH群体分别种植在干旱和正常滴水处理下，利用38737个单核苷酸多态性标记（SNPs）对41份亲本进行了全基因组扫描。41份亲本自交系间的遗传距离为0.05到0.74之间，依据遗传距离可以将其划分为5个杂种优势群。根据不同杂种优势群产生杂交种的表型（产量、生育期、株高），研究认为BSSS×NSS、NSS×SPT和BSSS×SPT这3种杂优模式在中国机收玉米育种中具有较大的利用价值。研究一般配合力和特殊配合力的比值表明，正常滴水下加性效应对单株产量的的影响较大，而在干旱处理下非加性效应对产量的影响力更大。干旱条件下高产的玉米杂交种其亲本之一必须是配合力较高或者抗旱性较好的玉米自交系。在一定的遗传距离（GD）范围内，GD和杂种产量和产量杂种优势呈正相关。本研究认为杂种优势是亲本优势基因位点逐步累加和亲本间最佳遗传距离共同作用形成的，干旱处理下的产量杂种优势主要由非加性效应决定的。 

本研究基于小麦Wheat55K SNP芯片鉴定到两个主效且稳定表达的小穗数QTL。其中，QSns.sau-2SY-2D.1在之前的研究中已经被报道，而本研究中新鉴定到一个QTL（QSns.sau-2SY-7A），我们对其进行了深入分析。QSns.sau-2SY-7A的LOD值较高，介于4.46至16.00之间，解释10.21-40.78％的表型变异。QSns.sau-2SY-7A位于染色体臂7AL上4.75-cM的区间，侧翼标记为AX-110518554和AX-110094527。我们对两个主效QTL的贡献和相互作用进行了深入的分析和讨论。我们进一步开发一个与QSns.sau-2SY-7A紧密连锁的KASP标记，在一个F_2:3群体和一个包含101个小麦高代育种品系的自然群体中对该QTL的效应进行了验证。此外，在QSns.sau-2SY-7A定位区间中，预测到一个水稻中报道的调控小穗数的同源基因WAPO1，结合前人报道，该基因很有可能是该位点的候选基因。综上所述，本研究系统揭示了被广泛用于育种亲本的品系‘20828’的多小穗数遗传基础，并开发获得紧密连锁标记，有助于后续主效QTL的精细定位和育种利用。

高等植物中，抗坏血酸过氧化物酶（APX）在清除活性氧的过程中发挥重要作用。中华猕猴桃因富含维生素C而成为具有重要经济和营养价值的园艺作物，其APX的相关研究及报道甚少。本研究分离鉴定出中华猕猴桃‘红阳’的两个细胞质APX基因（AcAPX1和AcAPX2）。两个基因的时空表达模式研究发现，两者分别在叶和根中表达量相对较高。氯化钠处理猕猴桃的根可以提高二者的转录水平。利用GFP融合蛋白的亚细胞定位分析显示两个蛋白均定位于细胞质中。两个基因的his标签重组蛋白成功得以原核表达，并测定出酶活。最后，两个基因在拟南芥中过表达可在盐胁迫处理下提高维生素C和谷胱甘肽的含量。我们的研究揭示了中华猕猴桃细胞质APX可保护猕猴桃免受环境不良刺激。

细胞死亡是多细胞生物生命中一种重要的生理现象。当呼吸和新陈代谢等正常功能停止时，将会发生细胞死亡。细胞死亡可分为程序性细胞死亡和非程序性细胞死亡。正常组织中发生的程序性细胞死亡，通常是维持组织机能和形态所必须的。非程序性细胞死亡则通常由非生物或生物胁迫引起。近年来，大量研究报道植物在抵御病原菌时出现了细胞死亡现象。通过分析调控植物免疫反应和细胞死亡的蛋白（PICD），发现PICD主要参与丝裂原活化蛋白激酶（MAPK）级联、活性氧（ROS）、植物激素、泛素-蛋白酶体系统、Ca²⁺信号、物质转运等六种主要的反应过程，且这些反应过程存在内在的联系。同时，PICD主要分为八类，如：含有核苷酸结合结构域和富含亮氨酸重复序列的蛋白（NLR）蛋白、受体或类受体激酶、E3泛素连接酶和其相关蛋白、ATP和GTP相关蛋白、转录因子、14-3-3蛋白和其相关蛋白、类eEF1A蛋白和丝氨酸蛋白酶抑制子，部分PICD类型具有单、双子叶植物特异性。植物细胞死亡不仅与病原相关分子模式激发的免疫反应（PTI）、效应因子激发的免疫反应（ETI）紧密相关，也与系统获得性抗性（SAR）存在重要关联。PICD在细胞外基质、细胞膜、细胞质、细胞核、线粒体、叶绿体、内质网膜、多囊泡体等众多细胞结构中均有分布，表明细胞在应对病原菌侵染和调控自身死亡时存在精妙地协同调控作用。此外，植物在抵御病原菌时的细胞死亡，通常对其自身的生长发育不利。通过筛选优异的等位变异和基因编辑等技术手段，期望达到植物免疫和生长发育间的平衡，以此增强PICD在植物应用领域中的潜力。

西瓜(Citrullus lanatus (Thunb.)Matsum. & Nakai)是世界范围内种植的一种重要的瓜类作物。西瓜果实品质、育性、结实率与雄花发育密切相关。本研究通过细胞学观察，对西瓜新品种‘新特大郑抗9号’雄花发育的不同阶段进行了区分，并进行了转录组测序分析。对花药进行醋酸洋红染色，并测定未开放雄花的纵横径。对花药不同发育时期的细胞学观察表明，花药从四分体生长到成熟期，其纵横径逐渐增大，雄花的花蕾长度在发育过程中也发生了显著的变化。对花药发育的四分体期(A组)、单核期(B组)、双核期(C组)和成熟期(D组)四个发育时期进行转录组测序分析。结果表明，四个阶段总共发现了16288个差异表达基因(DEGs)，随着发育阶段的延伸，各比较组间的DEGs数量逐渐增加，6个比较组(A-VS-B、A-VS-C、A-VS-D、B-VS-C、B-VS-D和C-VS-D)的DEGs分别为2014、3259、4628、1490、3495和1132个。GO和KEGG富集分析表明，DEGs主要富集于细胞组分、淀粉和蔗糖代谢、苯丙类生物合成和戊糖合成等途径。最后，我们在6个比较组中共筛选了59个DEGs，有趣的是，我们发现一个花粉特异表达蛋白(Cla001608)显著下调(log2Fold Change值高达17.32)，这表明它可能在雄花发育中起重要作用。本研究为了解西瓜雄性花发育阶段的分子基础提供了依据，并有助于优势杂交育种。

柑橘类水果富含酚类化合物，对人体具有多种健康益处。然而，很少有研究关注这类水果在采后贮藏过程中酚类化合物的变化。本研究对低温贮藏和留树保鲜12周的Tarocco血橙的酚类含量、成分和抗氧化活性进行了动态监测，并通过评估苯丙烷途径相关酶活性和基因表达探讨了血橙酚类化合物变化机制。结果表明，黄烷酮是血橙中主要酚类化合物，两种贮藏方式主要通过促进酚酸的积累从而提高总酚含量，并在第12周达到最大值。留树保鲜血橙的酚类含量和抗氧化性要高于低温贮藏血橙。此外，苯丙烷途径相关酶活性和基因表达结果显示，贮藏期间血橙中酚类物质的积累与苯丙烷途径的激活具有高度相关性。以上结果表明，从酚类化合物的角度来看，留树保鲜储存是延长血橙供应期的一种潜在有效方式。

了解小麦品质相关性状的遗传基础有助于对小麦品质进行改良，本实验测定了多环境下236份小麦种质资源（包括 160 个栽培品种和76个地方品种）的蛋白质含量（GPC）、淀粉含量（GSC）和湿面筋含量（WGC），并使用 55K小麦芯片进行了混合线性模型 (MLM)分析。结果共鉴定了 12 个稳定的 QTL/SNP，与GPC、GSC和WGC 相关的位点分别有3个、7个和2个 QTL，它们分别位于1B、1D、2A、2B、2D、3B、3D、5D 和 7D 染色体上；表型变异解释 (PVE) 范围从4.2 至10.7%。与之前报道的 QTL/基因相比，5 个 QTL（QGsc.sicau-1BL、QGsc.sicau-1DS、QGsc.sicau-2DL.1、QGsc.sicau-2DL.2、QWgc.sicau-5DL）是潜在的新位点。本实验着重关注了位于5D染色体上与湿面筋浓度相关的稳定QTL，并成功开发了SNP AX-108770574 和AX-108791420 两个KASP 标记。其中AX-108770574中含有A-等位基因和AX-108791420中含有T-等位基因的品种表型显着高于(P<0.01)含有湿面筋浓度G-等位基因或C-等位基因的地方品种，表明开发的KASP 标记可用于分子育种，改良小麦品质。

本试验探讨了7种不同类型缓控释肥一次性施用对水稻产量及群体特征的影响。在研究肥料氮素（N）释放特征的基础上，于2018和2019年进行盆栽试验，以常规分次施肥（CK，基穗比为1:1）为对照，对水稻叶片SPAD值、产量及其构成、茎蘖动态和干物质积累进行研究。结果表明：不同类型缓控释肥的氮素释放特征差异显著。树脂包衣尿素（PCU）表现为控释模式，整个生育期持续释放氮素；硫包衣尿素（SCU）表现为缓释模式，中后期氮素释放不足；脲酶抑制剂尿素（AHA）和脲甲醛（UF）表现为速释模式，前期爆发性释放，中后期无释放，但其供肥能力可持续到抽穗期。PCU延缓了高峰苗期，与CK相比，干物质积累、叶片SPAD值无显著差异，同时由于整个生育阶段氮素的持续释放，每穗粒数、结实率和千粒重增加，从而提高水稻产量；SCU由于后期氮供应不足，总颖花量低，水稻产量降低，但差异不显著；AHA和UF易受环境因素的影响，对产量的影响不一致。本试验结果表明，在盆栽等量施氮条件下，供肥能力强、有效持续时间长的肥料类型更有利于水稻后期干物质积累，提高产量。

一方面，中国亚热带红壤区水稻土母质和肥力水平多变；另一方面，细菌多样性和群落组成在土壤生态系统过程和功能中发挥关键作用。但是水稻土的母质和肥力对细菌多样性和群落组成的影响如何仍不清楚，不同母质和肥力水平条件下驱动水稻土细菌多样性、群落组成和特异微生物种群变化的关键因素尚不明确。因此，本研究采集亚热带红壤区具有不同母质（第四纪红黏土或第三纪红砂岩）和不同肥力水平（高肥力或低肥力）的典型样地水稻土样品，通过454高通量测序测定细菌16S rRNA基因的V4−V5区，分析细菌多样性指数和群落组成变化。采用two-way ANOVA和two-way PERMANOVA探明母质和肥力对细菌多样性和群落组成的影响；主坐标分析（PCoA）、冗余分析（RDA）和多元回归树分析（MRT）明确细菌群落的变化，以及驱动该变化的关键土壤因子；共现网络分析阐明属水平特异细菌种群和关键土壤因子的关系；宏基因组差异分析工具（STAMP）确定不同土壤样品间差异物种。结果显示，母质和肥力对水稻土细菌多样性指数变化的贡献相似。但是肥力水平对细菌群落组成的影响要远大于母质。土壤因子，特别是土壤质地与细菌多样性指数密切相关。RDA分析发现土壤有机碳（SOC）是影响细菌群落组成的首要因素，并且25.5 g kg⁻¹有机碳含量是驱动高肥力和低肥力土壤细菌群落组成分异的关键阈值。共现网络分析暗示高肥力水平下，由于土壤环境的改善，细菌趋向于合作关系，并且富营养型细菌占主导地位。STAMP分析发现高肥力水稻土中Massilia和Rhodanobacter等富营养型细菌大量富集；而低肥力土壤中Anaerolinea等贫营养型细菌占主导。研究结果表明，不同母质和肥力水稻土中，土壤质地影响细菌多样性指数变化；而养分水平，特别是有机碳水平决定细菌群落组成的变化。

In vitro gynogenesis is an important tool used in haploid or homozygous double-haploid plant breeding.  However, because of low repeatability, embryoid induction rate and quality, the molecular mechanisms remain poorly understood.  Heat shock treatment can promote the transformation of the gametophytic pathway into the sporophyte pathway, which induces the occurrence of haploid.  In this study, unfertilized ovaries were heat shocked for 0 h (A0) before flowering and for 0 h (A1), 4 h (A3), 8 h (A5), 12 h (A7), and 24 h (A8), respectively, at 37°C at the first day of the flowering stage.  The ovule enlargement rate was increased from 0% at 25°C to 96.8% at 37°C (24 h treatment).  Thus, we aimed to investigate the gene expression patterns in unfertilized ovules of watermelon after different periods of heat shock by using RNA-Seq technology.  The results showed that compared with A3, A5, A7, and A8, the biosynthesis of amino acid, glycine, serine and threonine metabolic pathways in A1 has changed significantly.  This indicated that heat shock treatment affected the synthesis and transformation of amino acids during ovule expansion.  The transcriptome data suggested gene expressions of ovule growth were significantly changed by heat-specific influences.  The results provide new information on the complex relationship between in vitro gynogenesis and temperature.  This provides a basis for further study of the mechanism of heat shock affecting the expansion of watermelon ovule. 

Nitrogen (N), the major forms of which are nitrate (NO₃^–) and ammonium (NH₄⁺), plays an important role in plant growth and mediation of root development.  However, the role of auxin in root growth in response to different NH₄⁺/NO₃^– ratios remains unclear.  Two tobacco cultivars (Nicotiana tabacum L.) were adopted in this study, which displayed variant growth features under the situations with sole NO₃^– nutrition ratio (NH₄⁺/NO₃^– ratio: 0/100), low NO₃^– nutrition ratio (NH₄⁺/NO₃^– ratio: 97/3), and optimal NH₄⁺/NO₃^– ratio (50/50).  We investigated the effects of the different NH₄⁺/NO₃^– ratios on the formation and elongation of lateral roots (LRs), auxin concentration, DR5::GUS expression, 3H-labeled indole acetic acid ([3H]IAA) transport, and the expression of six PIN genes in tobacco roots.  We also examined the effects of exogenous auxin and a transport inhibitor on LRs growth.  The results are shown as follows, compared to optimal N nutrition conditions, the biomass and nitrogen (N) accumulation were largely reduced by sole and low NO₃^– nutrition treatment in NC89, but no difference was observed in Zhongyan 100.  In most cases, sole and low NO₃^– nutrition impaired the elongation and formation of first-order lateral roots (1° LRs), only in NC89, thus reducing the root growth.  IAA concentration and DR5::GUS expression levels decreased in roots when NC89 was subjected to sole and low NO₃^– nutrition media, suggesting that different NH₄⁺/NO₃^– ratios affect the transport of auxin from leaves to roots.  Results were similar following exogenous NAA application to low NO₃^– nutrition treated seedlings.  Based on direct [3H]IAA transport measurement, the transport of polar auxin from shoots to roots decreased due to low NO₃^– nutrition.  PIN4 expression levels were markedly decreased in roots of NC89 by sole and low NO₃^– nutrition, while they were unaffected in Zhongyan 100 roots.  Overall, our findings suggest that LRs formation in tobacco seedlings is regulated by NH₄⁺/NO₃^– ratios via modifying polar transport of auxin.

Received  7 June, 2017    Accepted  13 October, 2017

The optimized nitrogen fertilization location differs in different rice-growing regions.  We optimized nitrogen deep-point application in root-growing zone (NARZ) for transplanted rice in subtropical China.  Field plot experiments were conducted over two years (2014–2015) in a double-rice cropping system to evaluate the effects of nitrogen (N) fertilizer location on grain yield and N use efficiency (NUE).  Four different nitrogen deep-point application methods (DN) were compared with traditional broadcast application (BN) using granular urea.  The results showed that grain yield,  recovery efficiency of N (RE_N), agronomic efficiency of N (AE_N), and partial factor productivity of N (PFP_N) significantly increased 10.3–63.4, 13.7–56.7, 24.7–201.9 and 10.2–63.4%, respectively, in DN treatment compared to BN, respectively.  We also find that DN treatments increased grain yield as well as grain N content, and thus grain quality, in comparison with conventional BN treatment.  Correlation analysis indicated that significant improvement in grain yield and NUE mainly resulted from increases in productive panicle number and grain N content.  In our proposed NARZ method, granular urea should be placed 0 to 5 cm around the rice seeding at a 12-cm depth druing rice transplanting.  In NARZ, balanced application of N, P and K further improved grain yield and NUE over treatments with a single N deep-point application.  High N uptake by the rice plant did not cause significant soil fertility depletion, demonstrating that this method could guarantee sustainable rice production.    
 

Oryza ridleyi is an allotetraploid wild species with the HHJJ genome, and Oryza sativa is a diploid cultivated rice that has the AA genome. Although the wide hybrid between the two species is difficult to obtain, we overcome this difficulty by young embryo rescue. An obvious heterosis was primarily found for the plant height, tillering ability, vegetative vigor, etc. However, the hybrid panicle and culm traits were found to resemble that of the wild rice parent, O. ridleyi, for the long awns, exoteric purple stigma, grain shattering, dispersed panicles, and culm mechanical strength. Genomic in situ hybridization (GISH) analysis was subsequently performed on the mitotic metaphase chromosome of the root tips, and we determined that the hybrid is an allotriploid with 36 chromosomes and its genomic constitution is AHJ. Chemical analyses conducted on the culm of O. sativa, O. ridleyi, and their interspecific hybrids showed that major changes occurred in the xylose, glucose, and arabinose concentrations, which are correlated with the specific hemicellulose polymer and cellulose components that are important in the primary cell walls of green plants. Meanwhile, the culm anatomical analyses indicated that additional large vascular bundles and an extra sclerenchyma cell layer were found in O. ridleyi. Additionally, further thickening of the secondary cell walls of the cortical fiber sclerenchyma cells and the phloem companion cells was discovered in O. ridleyi and in the interspecific hybrids. These results imply that there may be a potential link between culm mechanical strength and culm anatomical structure.

Genes controlling fruit appearance determine fruit shape and size.  In ethylmethane sulfonate (EMS)-mutagenized lines of Fragaria vesca accession Yellow Wonder (YW), two fruit shapes are observed: wild-type long fruit and mutated shortened fruit (sf).  In this study, we first characterized sf based on morphology, histology, cytology and physiology.  The sf was identified as a gibberellin (GA)-deficient mutant, and four complementary DNA (cDNA) libraries separately constructed from flower buds and small green fruits of YW and sf were sequenced to comparatively analyze transcriptome differences.  A total of 29 differentially expressed GA pathway genes were identified by comparisons between YW1 and sf1, and 28 differentially expressed GA pathway genes were identified between YW2 and sf 2.  In addition, the expression patterns of 45 differentially expressed genes were validated by quantificational real-time PCR (qRT-PCR), and the results were highly concordant with the RNA-Seq results.  This transcriptome analysis provides valuable information for understanding the molecular mechanisms of fruit development of strawberry.

     Heterosis is an important biological phenomenon, and it has been used to increase grain yield, quality and resistance to abiotic and biotic stresses in many crops. However, the genetic mechanism of heterosis remains unclear up to now. In this study, a set of 184 chromosome segment substitution lines (CSSLs) population, which derived from two inbred lines lx9801 (the recurrent parent) and Chang 72 (the donor parent), were used as basal material to construct two test populations with the inbred lines Zheng 58 and Xun 9058. The two test populations were evaluated in two locations over two years, and the heterotic loci for plant height and ear height were identified by comparing the performance of each test hybrid with the corresponding CK at P<0.05 significant level using one-way ANOVA analysis and Duncan’s multiple comparisons. There were 24 and 29 different heterotic loci (HL) identified for plant height and ear height in the two populations at two locations over two years. Three HL (hlPH4a, hlPH7c, hlPH1b) for plant height and three (hlEH1d, hlEH6b, hlEH1b) for ear height were identified in the CSSLs×Zheng 58 and CSSLs×Xun 9058 populations as contributing highly to heterosis performance of plant height and ear height across four environments. Among the 29 HL identified for ear height, 12 HL (41.4%) shared the same chromosomal region associated with the HL (50.0%) identified for plant height in the same test population and environment.

    Information on the center of genetic diversity of soybean (Glycine max) will be helpful not only for designing efficient strategies for breeding programs, but also for understanding the domestication and origin of this species. Here, we describe an analysis of genetic diversity based on simple-sequence repeat (SSR) variations within a core collection of 2 111 accessions of Chinese soybean landraces. Prior to the diversity assessment, the geographic origin of each accession was mapped. The map was then divided into grids each 2.5° in latitude and 5° in longitude. We found two regions that had higher number of alleles (NA) and greater polymorphic information content (PIC) values than the others. These regions are adjacently located within grid position of 30°–35°N×105°–110°E, which includes the valley of the middle and lower reaches of the Wei River, and the valley of the upper reaches of the Hanjiang River. It was also observed that in many regions, genetic diversity decreased with the increase in distance from the center. Another region, in northern Hebei Province (115°–120°E×40°–42.5°N), was observed having higher diversity than any surrounding regions, indicating that this is a sub-center of soybean diversity. Based on the presented results, the domestication and origin of soybean are also discussed.

As one of the staple food crops, rice (Oryza sativa L.) is widely cultivated across China, which plays a critical role in guaranteeing national food security. Most previous studies on grain yield or/and nitrogen use efficiency (NUE) of rice in China often involved site-specific field experiments, or small regions with insufficient data, which limited the representation for the current rice production regions. In this study, a database covering a wide range of climate conditions, soil types and field managements across China, was developed to estimate rice grain yield and NUE in various rice production regions in China and to evaluate the relationships between N rates and grain yield, NUE. According to the database for rice, the values of grain yield, plant N accumulation, N harvest index (HIN), indigenous N supply (INS), internal N efficiency (IEN), reciprocal internal N efficiency (RIEN), agronomic N use efficiency (AEN), partial N factor productivity (PEPN), physiological N efficiency (PEN), and recover efficiency of applied N (REN) averaged 7.69 t ha–1, 152 kg ha–1, 0.64 kg kg–1, 94.1 kg kg–1, 53.9 kg kg–1, 1.98 kg kg–1, 12.6 kg kg–1, 48.6 kg kg–1, 33.8 kg kg–1, and 39.3%, respectively. However, the corresponding values all varied tremendously with large variation. Rice planting regions and N rates had significant influence on grain yield, N uptake and NUE values. Considering all observations, N rates of 200 to 250 kg ha–1 commonly achieved higher rice grain yield compared to less than 200 kg N ha–1 and more than 250 kg N ha–1 at most rice planting regions. At N rates of 200 to 250 kg ha–1, significant positive linear relationships were observed between rice grain yield and AEN, PEN, REN, IEN, and PFPN, and 46.49, 24.64, 7.94, 17.84, and 88.24% of the variation in AEN, PEN, REN, IEN, and PFPN could be explained by grain yield, respectively. In conclusion, in a reasonable range of N application, an increase in grain yield can be achieved accompanying by an acceptable NUE.

Contamination of deoxynivalenol (DON) in grains is common worldwide and pigs are particularly susceptible to this mycotoxin. The distribution of DON in porcine tissues following intravenous administration was investigated in this study. Fifteen pigs were randomly divided into three groups. Animals in groups A and B were administrated with DON at the dose of 250 and 750 μg kg–1 body weight, respectively, while group C served as blank control. Plasma, bile and 27 tissues were collected at 30 min post-administration. DON concentrations in all samples were tested using high-performance liquid chromatography- tandem mass spectrometry (HPLC-MS/MS). To observe the distribution of DON in tissues, these samples were further subjected to the immunohistochemical analyses. Totally, the bile and 13 tissues were sampled for DON-based detection, including kidney, mesenteric lymph nodes, muscle, stomach, jejunum, colon, plasma, spleen, rectum, cecum, liver, ileum, and duodenum. No significant difference was observed for the concentrations of DON in duodenum, ileum and liver samples between groups A and B; while the DON concentrations in cecum and rectum of group B were significantly higher (P-value <0.05) than those in group A. In addition, the DON concentrations in stomach, jejunum, colon, mesenteric lymph nodes, muscle, kidney, spleen, bile, and plasma of group B were remarkably higher than those of group A (P-value<0.01). Levels of DON in other 14 tissues including medulla oblongata, midbrain, diencephalon, pons, tip and tongue body, tongue, soft palate, tonsils, pharyngeal mucosa, oral buccal mucosa, thymus, thyroid, esophagus and adrenal gland were all below the limit of detection. The results of immunohistochemistry showed that 11 tissue samples (medullaoblongata, tonsil, adrenal medulla, thyroid gland, thyroid, stomach, duodenum, jejunum, kidney, spleen, and mesenteric lymph nodes) were positive and DON was mainly distributed around blood vessels in these tissues. Therefore, we believed that concentrations of DON in tissues differ when pigs are in exposure to various dosages and DON causes lesions in many pig tissues.