防御素在植物的生长发育和抵御病原菌侵染过程中发挥重要的作用，然而苹果中防御素对苹果树腐烂病菌抗性的作用尚不清楚。本研究中，共鉴定出29个苹果防御素蛋白，它们具有保守的序列特征。基于表达分析，发现苹果防御素在苹果各组织中均有分布，5个防御素基因的表达受到苹果壳囊孢的显著诱导。构建5个防御素的转基因愈伤，过表达防御素基因均能增强对苹果壳囊孢的抗性。其中，MdDEF30表达受苹果壳囊孢菌强烈诱导并显著提高愈伤抗性。进一步的体外活性实验证实MdDEF30能抑制壳囊孢的生长。MdDEF30能够促进活性氧积累和激活防卫相关基因PR4，PR10，CML13及MPK3的表达。通过构建MdDEF30共表达网络，发现转录因子MdWRKY75可能调控MdDEF30的表达。利用酵母单杂、荧光酶素报告基因和染色质免疫共沉淀荧光定量实验证实MdWRKY75能够与MdDEF30启动子直接结合。接种实验表明MdWRKY75正调控对苹果树腐烂病抗性，并且激活MdDEF30的表达。这些结果阐明苹果树通过MdWRKY75正向调控具抗菌活性和诱导抗性的MdDEF30表达抵御壳囊孢菌侵染的分子机理。

全球花生品种多样，花生的特性和营养决定了产品品质。然而，全球花生籽仁的关键品质指标的比较分析和统计学分析相对薄弱，阻碍了全球花生品质评价和花生产业发展。本研究以主要花生生产国的10个不同花生品种为研究对象，对花生籽仁的表观形态、微观结构、单细胞结构、工程特性和质构特性以及主要营养成分含量进行对比分析。花生籽仁的表面和截面微观结构均呈致密的“块状”形貌，细胞结构明显。细胞内脂滴呈球形，均匀分布在细胞内。10个花生品种籽仁的单细胞结构表现出不同的形态和尺寸，并发现这与质构和工程特性相关。此外，花生籽仁的质量损失随温度变化呈5个不同的阶段，分别为水分流失、挥发性损失、蛋白质变性和各种生物大分子的降解等的过程。不同花生品种间脂肪、蛋白质、蔗糖含量以及质构、堆积密度、真实密度、孔隙率、几何平均直径、圆度和球形度均存在差异。本研究建立了主要花生加工国家常见花生品种的微观结构、工程性能和营养成分之间的关联和相关性。研究结果为全球花生品质评价和花生产业提供了有价值数据和见解。

为建立针对克里米亚-刚果出血热病毒（Crimean-Congo hemorrhagic fever virus, CCHFV）的简单、快速、适用于现地使用的核酸检测方法，本研究首先比对了20株来自不同国家不同时间分离的CCHFV毒株基因序列，筛选出保守的S基因作为检测靶标，并以中国分离株（YL16070）的S基因保守序列为模板，设计、合成和筛选出反转录重组聚合酶介导恒温扩增（RT-RAA）特异性引物和探针。为实现检测结果的可视化，将四氢呋喃（THF）取代探针3' 端附近的胸腺嘧啶，在探针3' 端引入了阻断基团三碳间隔（C3 spacer），同时对探针和下游引物的5' 端分别使用FAM和生物素标记，最后结合胶体金免疫层析试纸，建立了一种针对CCHFV S基因的可视化快速检测方法CCHFV RT-RAA-VF。为了提高方法的敏感性，对反应温度、反应时间和引物浓度进行了优化，结果显示该方法以浓度为10μM的引物在42 ℃恒温条件下扩增30 min时敏感性最高，最低可检出20 copies μL^-1的阳性质粒和2 copies μL^-1的CCHFV RNA转录本。克里米亚-刚果出血热症状与许多出血热病毒感染症状类似，因此将CCHFV与其他可引起出血热的病毒区分开来非常重要。为了评估所建立方法的特异性，分别检测了登革热病毒（DENV）、日本脑炎病毒（JEV）、埃博拉病毒（EBOV）、亨德拉病毒（HeV）、尼帕病毒（NIV）及CCHFV的核酸，结果表明，该方法仅能识别 CCHFV的核酸，与其他病原无交叉反应。最后为评估该方法的准确性和临床适用性，本研究将所建立的方法与已有的RT-qPCR方法对模拟样品进行平行检测，结果显示两者检测符合率为100%。综上表明，本研究建立的CCHFV RT-RAA-VF快速检测方法敏感性高、特异性好、准确性高，且操作简单、无需特殊仪器，可应用于野外或基层单位的CCHFV快速筛查检测工作，在一定程度上响应了世界卫生组织在2018年提出的CCHF研究路线图草案。

伪狂犬病（Pseudorabies，PR）是由伪狂犬病病毒（Pseudorabies virus, PRV）引起的猪的一种急性传染病，给养猪业造成严重的经济损失。基因缺失活疫苗的广泛使用有效控制了该病的大范围暴发。尤其是gE基因缺失活疫苗配合其血清学鉴别诊断方法区分疫苗免疫和野毒株感染，为该病在猪群中的净化提供了技术支撑。目前，已有多种以gE蛋白为包被抗原的PRV抗体检测的ELISA方法被应用于野毒感染的筛查。然而，该类ELISA试剂盒大多基于传统抗体研发，其生产工艺复杂，成本高。纳米抗体具有抗原结合力强、耐极端环境、易基因工程改造和体外生产成本低等优点，已广泛用于疫病诊断技术的研发，具有巨大的市场应用前景。然而，目前还没有关于纳米抗体在PRV诊断与治疗中应用的研究报道。本研究用gE重组蛋白免疫双峰驼，并利用噬菌体展示文库筛选出了2株抗gE重组蛋白的特异性纳米抗体。随后，将纳米抗体与辣根过氧化物酶（HRP）融合表达，建立了基于纳米抗体-HRP猪血清PRV-gE抗体阻断ELISA（bELISA）方法。确定以PRV-Nb36-HRP为检测探针建立PRV-gE抗体bELISA，其条件为抗原包被量为每孔200 ng，Nb36-HRP和待检猪血清的稀释度分别为1：320和1：5。bELISA方法的临界值为24.20%，敏感性和特异性分别为96.43%和92.63%。与商品化IDEXX ELISA试剂盒的符合率为93.99%。此外，通过表位分析发现PRV-gE-Nb36识别的构象表位在不同PRV参考株中高度保守。本研究建立了一种基于纳米抗体的操作简单、稳定性高、重复性好、成本低的PRV-gE抗体bELISA检测方法，为PR的监测和净化提供创新型诊断试剂。本研究首次以纳米抗体融合HRP作为检测探针建立PRV-gE抗体bELISA检测方法，无需酶标二抗的使用，简化了生产工艺，节约了生产成本。

磷（P）是活体植物必不可少的重要元素。缺磷是制约世界油菜产量的关键因素之一。作为植物最重要的器官，根的形态在磷的吸收中起着关键作用。为了研究低磷有效性下根形态的遗传变异性，我们通过全基因组关联研究（GWAS）、连锁作图和候选基因关联研究（CGAS）对跟的形态性状相关的基因结构进行了剖析。在405份油菜自然群体中，共检测到52个重要的标记位点与磷胁迫下的根系形态性状相关。其中，在低磷胁迫下的侧根数（LRN）和根干重（RDW）性状位点中共同检测到紫色酸性磷酸酶基因-BnPAP17。在低磷胁迫下，高效磷品种的地上部组织中BnPAP17的表达比根组织和低效磷品种的表达增加。此外，还检测到BnPAP17^Hap3单倍型在油菜磷高效育种中受到了选择。过量表达该单倍型能显著促进油菜的地上部和根部生长，增强油菜对低磷胁迫的耐受性和对有机磷的利用。综上所述，这些发现增加了我们对BnPAP17在介导油菜低磷胁迫中的分子机制的认识。

水稻冠层温度与植株生理特性紧密联系，是直接影响产量形成的重要因素。但不同氮肥处理下水稻全生育期冠层温度的变化规律及其与水稻生长的关系尚待明确。本研究选择了当地常用的水稻品种淮稻5号、南粳9108和扬粳805为材料，设置了不施氮肥（CK），中氮（MN，200 kg ha^–1）和高氮（HN，300 kg ha^–1） 三个氮肥梯度，进行了两年重复试验。利用无人机搭载高精度摄像头，测定种植在同一大田环境条件下水稻冠层温度的全生育期动态变化。结果表明不同氮肥处理下水稻冠层温度在分蘖、拔节、孕穗、抽穗期这四个时期不施氮肥处理的冠层温度显著高于中氮和高氮处理（p=0.05），而乳熟、蜡熟期则无显著差异。不同品种水稻的冠层温度表现为淮稻5号大于南粳9108大于扬粳805，但差异不显著。水稻冠层温度主要与地上部鲜重（相关系数r=-0.895）、植株含水率（-0.912）、剑叶净光合速率（-0.84）、气孔导度（-0.91）、蒸腾速率（-0.90）、气孔面积（-0.83）等性状相关，结构方程模型（SEM）表明氮肥是直接影响水稻冠层温度的最重要的因子，同时氮肥通过影响水稻叶片气孔面积、蒸腾速率和气孔导度，间接影响了水稻冠层温度。抽穗期是研究水稻冠层温度的最佳时期，此时水稻冠层温度与产量、穗数和每穗粒数呈极显著负相关关系，冠层温度的高低可成为反映水稻生长及预测产量的便捷而较准确的指标。

黄龙病是一种由Candidatus Liberibacter asiaticus (CLas) 引起韧皮部寄生的革兰氏阴细菌，主要由亚洲柑橘木虱以持久增殖的方式传播，是柑橘上最具毁灭性的病害。有研究提出，黄龙病菌借助木虱细胞内的囊泡结构来复制和传播。然而，黄龙病菌如何进入木虱细胞以及囊泡运输作用在此过程中起到何种作用目前尚不清楚。本研究中，我们监测木虱五龄若虫在不同取食时间后体内CLas滴度的变化，结果表明，若虫体内的CLas滴度随着取食时间的延长而增加。在CLas感染的木虱体内囊泡转运相关基因的表达显著上调，当阻断木虱内吞作用和内体网络后，CLas在木虱整虫和中肠的滴度显著下降。此外，通过沉默网格蛋白重链基因（dsCHC1）的表达同样导致了柑橘木虱体内CLas滴度的降低。总而言之，我们的结果表明，CLas感染上调了柑橘木虱囊泡运输相关基因的表达，从而促进了依赖内吞作用病原菌的入侵。

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。

华南双季稻持续突破总产量纪录，而单季稻的产量潜力未能实现。辐射利用效率（RUE）被认为是谷类作物产量的重要决定因素。然而，目前尚无关于双季稻的产量差异是否涉及到RUE的信息。为了评估截获辐射（IP）和RUE对华南双季稻区4个代表性品种（象牙香占、美香占2号、南晶香占、软华优金丝）在早季和晚季的地上部生物量、作物生长速率（CGR）和收获指数（HI）的影响，开展了为期两年的田间试验。早稻的产量比晚稻高8.2%。早稻的产量优势主要源于较高的RUE决定的更高的每穗粒数和地上部生物量。象牙香占、美香占2号、南晶香占和软华优金丝在早稻种植的每穗粒数比晚稻分别高出6.5%、8.3%、6.9%和8.5%。早稻较高的产量与分蘖中期RUE（R²=0.34）、幼穗分化期RUE（R²=0.16）、成熟期RUE（R²=0.28）和截获光合有效辐射（R²=0.28）密切相关，而晚稻的产量则更多的依赖于分蘖中期的截获光合有效辐射（R²=0.31）和幼穗分化期的截获光合有效辐射（R²=0.23）。较高的RUE有助于早稻的产量提高，而晚稻产量的提高主要依赖于生育早期更高的光合有效辐射。因此，合理调配双季稻的RUE，选择具有较高RUE的品种或调整播期等途径值得更长远的研究。

土壤中的氮素分布不均，在氮素富集的土壤区域内，植物根系大量的生长。然而，不同玉米基因型根系对局部施氮的响应与氮素吸收效率之间的关系尚不清楚。本研究以4个玉米品种为研究对象，探讨根系生长对局部施氮响应的基因型差异及对氮素吸收的影响。在水培采用分根培养体系局部供氮，在田间采用条施和穴施的局部施氮方法。结果表明，不同品种根系局部氮响应在水培和田间条件之间具有高度相关性（r>0.99）。在水培局部供氮条件下，强响应品种郑单958、先玉335和先锋32D22的侧根长增加了50-63%，根系生物量增加了36-53%，而弱响应品种蠡玉13的根系生长响应较小。田间条件下，3个强响应品种的根长在40-60 cm土层显著增加66-75%，而蠡玉13的根长变化幅度显著较低。此外，局部施氮肥促进强响应品种的花后氮吸收，增幅达16-88%，并且促进了郑单958的籽粒产量显著增加10-12%。相关分析发现，产量与40-60 cm土层根长呈显著正相关（r=0.39）。综上所述，可在苗期鉴定玉米品种对局部施氮的响应类型，生产中强响应型玉米品种与局部施用氮肥配套应用；同时可将“根系局部施氮响应能力”作为玉米氮高效遗传改良的目标性状。

本文利用玉米水培分根体系发现，局部供铵到缺氮根系可以显著诱导ZmAMT1;1a与ZmAMT1;3基因的表达水平。测定¹⁵N标记铵吸收速率与根组织氨基酸含量发现，铵诱导的ZmAMT1s基因表达与根系铵吸收能力及谷氨酰胺含量显著正相关。外界添加谷氨酰胺合成酶抑制剂MSX时，供铵则不能诱导缺氮根系中ZmAMT1;1a与ZmAMT1;3基因的表达，表明铵的同化产物谷氨酰胺，而不是铵本身，负责调控ZmAMT1s基因表达。此外，外界供应不同浓度谷氨酰胺到缺氮根系发现，较低浓度的谷氨酰胺就能够诱导ZmAMT1s基因表达，但高浓度谷氨酰胺却能够抑制其表达。以上研究结果表明，为了严格调节玉米根系铵吸收能力，铵转运蛋白ZmAMT1s基因在转录水平被严谨调控，与根内谷氨酰胺水平密切相关。

本研究通过两年大田试验，以两个高产超级稻品种为试验材料，设置了不施用氮肥、高氮肥投入的当地农民习惯栽培方式、优化氮肥管理措施1和优化氮肥管理措施2共计四种氮肥管理方式。试验结果表明通过控制氮肥投入总量、增加种植密度和优化氮肥追施比例等措施，实现高产优质和氮肥利用率的提高。与当地农民习惯相比，优化氮肥管理分别提高了产量和氮肥偏生产力1.70%和13.06%，提高了籽粒淀粉和直链淀粉含量，显著降低了蛋白质含量。在优化氮肥管理下，支链淀粉短支链A链(DP6-12)和B1链(DP13-25)含量显著增加，淀粉结晶度显著下降，同时淀粉的粘度值增加，淀粉的热力学特性变优，从而提高了稻米的蒸煮与食味品质。以上研究结果表明优化氮肥管理可以缓解高产水平条件下因大量氮肥投入而引起的稻米品质变劣，实现高产优质和氮肥利用率的协同提高的目标，对水稻的高产优质生产具有实践和指导意义。

Improved estimates of nutrient requirements for rice (Oryza sativa L.) in China are essential to optimize fertilization regulation for increasing grain yields and reducing the potential of environmental negative influences, especially under high-yielding intensive systems. A database involving rice grain yields, nutrient concentrations and accumulations collected from on-field station experiments in the literatures published from 2000 to 2013 in China was developed to understand the relationships between grain yields and plant nutrient uptakes, and to quantify nutrient requirements for different yield levels. Considering all data sets, rice grain yield ranged from 1.4 to 15.2 t ha^–1 with the mean value of 7.84 t ha^–1, and ca. 10.4% of yield observations were higher than the yield barrier level of 10 t ha^–1. N requirement to produce one ton grain was 21.10 kg for the yield range <4.0 t ha^–1 with a high variation of 45.8%. Except of the yield range <4.0 t ha^–1, the values of N requirement, firstly increased from 18.78 kg for yield range 4.0–5.5 t ha^–1 to 20.62 kg for yield range 7.0–8.5 t ha^–1, then decreased slightly to 19.67 and 19.17 kg for the yield range 8.5–10 and >10 t ha^–1, respectively. Phosphorus (P) and potassium (K) requirements showed increasing trends, from 3.51 and 19.87 kg per t grain for <4.0 t ha^–1 yield range to 4.10 and 21.70 kg for >10.0 t ha^–1 range. In conclusion, nutrient requirement varied with increasement of grain yield, and N, P and K presented various response trends, increasing, declining or stagnating, which would be of great benefit for improving fertilizer strategies.

     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.

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.

Aldehyde dehydrogenases (ALDHs) represent a large protein family, which includes several members that catalyze the oxidation of an aldehyde to its corresponding carboxylic acid in plants. Genes encoding members of the ALDH7 subfamily have been suggested to play important roles in various stress adaptations in plants. In this study, quantitative RT-PCR analysis revealed that a maize ALDH7 subfamily member (ZmALDH7B6) was constitutively expressed in various organs, including roots, leaves, immature ears, tassels, and developing seeds. The abundance of ZmALDH7B6 mRNA transcripts in maize roots was increased by ammonium, NaCl, and mannitol treatments. To further analyze tissue-specific and stress-induced expression patterns, the 1.5-kb 5´-flanking ZmALDH7B6 promoter region was fused to the β-glucuronidase (GUS) reporter gene and introduced into maize plants. In roots of independent transgenic lines, there was significant induction of GUS activity in response to ammonium supply, confirming ammonium-dependent expression of ZmALDH7B6 at the transcript level. Histochemical staining showed that GUS activity driven by the ZmALDH7B6 promoter was mainly localized in the vascular tissues of maize roots. These results suggested that ZmALDH7B6 is induced by multiple environmental stresses in maize roots, and may play a role in detoxifying aldehydes, particularly in vascular tissue.

Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize (Zea mays L., cv. Zhengdan 958) were grown in hydroponics with the control (4 mmol L-1) or low-nitrogen (40 μmol L-1) for 12 d, supplied as nitrate. Low nitrogen enhanced root elongation rate by 4.1-fold, accompanied by increases in cell production rate by 2.2-fold, maximal elemental elongation rate (by 2.5-fold), the length of elongation zone (by 1.5-fold), and final cell length by 1.8-fold. On low nitrogen, the higher cell production rate resulted from a higher cell division rate and in fact the number of dividing cells was reduced. Consequently, the residence time of a cell in the division zone tended to be shorter under low nitrogen. In addition, low nitrogen increased root diameter, an increase that occurred specifically in the cortex and was accompanied by an increase in cell number. It is concluded that roots elongates in response to low-nitrogen stress by accelerating cell production and expansion.

Maize plants adapt to low phosphorus (P) stress by increasing root growth. It is of importance to know the extent to which genetic improvement of root growth can enhance P acquisiton. In the present study, the contribution of root growth improvement to efficient P acquisition was evaluated in two soils using T149 and T222, a pair of near isogenic maize testcrosses which were derived from a backcross BC4F3 population. T149 and T222 showed no difference in shoot biomass and leaf area under normal growth conditions, but differed greatly in root growth. T149 had longer lateral roots and a larger root surface area compared to T222. In calcareous soil, when P was insufficient, i.e., when P was either supplied as KH2PO4 at a concentration of 50 mg P kg-1 soil, or in the form of Phy-P, Ca3-P or Ca10-P, a 43% increase in root length in T149 compared to T222 resulted in an increase in P uptake by 53%, and shoot biomass by 48%. In acid soil, however, when P supply was insufficient, i.e., when P was supplied as KH2PO4 at a concentration of 100 mg P kg-1 soil, or in the form of Phy-P, Fe-P or Al-P, a 32% increase in root length in T149 compared to T222 resulted in an increase in P uptake by only 12%, and shoot biomass by 7%. No significant differences in the exudation of organic acids and APase activity were found between the two genotypes. It is concluded that genetic improvement of root growth can efficiently increase P acquisition in calcareous soils. In acid soils, however, improvements in the physiological traits of roots, in addition to their size, seem to be required for efficient P acquisition.

Powdery mildew (Blumeria graminis) is one of the most destructive crop diseases infecting winter wheat plants, and has devastated millions of hectares of farmlands in China. The objective of this study is to detect the disease damage of powdery mildew on leaf level by means of the hyperspectral measurements, particularly using the continuous wavelet analysis. In May 2010, the reflectance spectra and the biochemical properties were measured for 114 leaf samples with various disease severity degrees. A hyperspectral imaging system was also employed for obtaining detailed hyperspectral information of the normal and the pustule areas within one diseased leaf. Based on these spectra data, a continuous wavelet analysis (CWA) was carried out in conjunction with a correlation analysis, which generated a so-called correlation scalogram that summarizes the correlations between disease severity and the wavelet power at different wavelengths and decomposition scales. By using a thresholding approach, seven wavelet features were isolated for developing models in determining disease severity. In addition, 22 conventional spectral features (SFs) were also tested and compared with wavelet features for their efficiency in estimating disease severity. The multivariate linear regression (MLR) analysis and the partial least square regression (PLSR) analysis were adopted as training methods in model development. The spectral characteristics of the powdery mildew on leaf level were found to be closely related with the spectral characteristics of the pustule area and the content of chlorophyll. The wavelet features performed better than the conventional SFs in capturing this spectral change. Moreover, the regression model composed by seven wavelet features outperformed (R2=0.77, relative root mean square error RRMSE=0.28) the model composed by 14 optimal conventional SFs (R2=0.69, RRMSE=0.32) in estimating the disease severity. The PLSR method yielded a higher accuracy than the MLR method. A combination of CWA and PLSR was found to be promising in providing relatively accurate estimates of disease severity of powdery mildew on leaf level.

Two Klebsiella pneumoniae isolates (Kpc1 and Kpc2) were obtained from liver samples of seven dead chickens and identified with Vitek-32 automated identification system. Antimicrobial susceptibilities were determined by the microdilution broth method. Detection of genes encoding class A b-lactamases was performed by PCR amplification, and cloning of the ESBL gene was by plasmid restriction and fragments ligation. Conjugation assay, transformation experiments and plasmid profile analysis were performed. The incompatibility group of ESBL-carrying plasmid was determined by the PCR-based replicon typing method. Lastly, the genetic environment was analysed by direct sequencing of the DNA surrounding the ESBL gene. The genes associated with tetracycline and gentamicin resistance were also sought by PCR. The results revealed that the ESBL phenotype-negative strain Kpc2 only showed resistance to ampicillin, amoxicillin, tetracycline, and doxycycline and carried blaTEM-1 and tet(A) genes. The ESBL-producing strain Kpc1 exhibited multidrug resistant phenotype and harbored blaTEM-1, blaCTX-M-14, tet(A), tet(B), and rmtB genes. K. pneumoniae Kpc1 contained four plasmids with molecular sizes of approximately 59, 6.9, 2.8, and 1.6 kb, but only a 59-kb plasmid, carried blaTEM-1 and blaCTX-M-14 genes, was observed in its transconjugant. The incompatibility group of plasmid carrying blaCTX-M-14 gene could not be determined. The blaCTX-M-14 gene was flanked upstream by an ISEcp1 insertion sequence and downstream by an IS903 element. This work shows that CTX-M-14 is present in K. pneumoniae isolates from chickens in China. The blaCTX-M-14 gene was associated with an upstream ISEcp1 insertion sequence. Our results underline the need for continuous surveillance of the prevalence and evolution of this CTX-M-type b-lactamase in China.