Simultaneous identification of plant stresses and diseases in arable crops using proximal optical sensing and self-organising maps

The objective of this research was to detect plant stress caused by disease infestation and to discriminate this type of stress from nutrient deficiency stress in field conditions using spectral reflectance information. Yellow Rust infected winter wheat plants were compared to nutrient stressed and healthy plants. In-field hyperspectral reflectance images were taken with an imaging spectrograph. A normalisation method based on reflectance and light intensity adjustments was applied. For achieving high performance stress identification, Self-Organising Maps (SOMs) and Quadratic Discriminant Analysis (QDA) were introduced. Winter wheat infected with Yellow Rust was successfully recognised from nutrient stressed and healthy plants. Overall performance using five wavebands was more than 99%.     

盐胁迫下一氧化氮的作用及信号传导研究进展

生物体内的一氧化氮能够提高植物对生物和非生物胁迫的耐受反应.对一氧化氮的产生、信号传导途径及其在盐胁迫下的作用进行了阐述,为更加全面了解生物体内一氧化氮的调控机制提供参考.     

‘Extended spectral angle mapping (ESAM)’ for citrus greening disease detection using airborne hyperspectral imaging

Hyperspectral (HS) imaging is becoming more important for agricultural applications. Due to its high spectral resolution, it exhibits excellent performance in disease identification of different crops. In this study, a novel method termed ‘extended spectral angle mapping (ESAM)’ was proposed to detect citrus greening disease (Huanglongbing or HLB), which is a very destructive disease of citrus. Firstly, the Savitzky–Golay smoothing filter was used to remove spectral noise within the data. A mask for tree canopy was built using support vector machine, to separate the tree canopies from the background. Pure endmembers of the masked dataset for healthy and HLB infected tree canopies were extracted using vertex component analysis. By utilizing the derived pure endmembers, spectral angle mapping was applied to differentiate between healthy and citrus greening disease infected areas in the image. Finally, most false positive detections were filtered out using red-edge position. An experiment was carried out using an HS image acquired by an airborne HS imaging system, and a multispectral image acquired by the WorldView-2 satellite, from the Citrus Research and Education Center, Lake Alfred, FL, USA. Ground reflectance measurement and coordinates for diseased trees were recorded. The experimental results were compared with another supervised method, Mahalanobis distance, and an unsupervised method, K-means, both of which showed a 63.6 % accuracy. The proposed ESAM performed better with a detection accuracy of 86 % than those two methods. These results demonstrated that the detection accuracy using HS image could be enhanced by focusing on the pure endmember extraction and the use of red-edge position, suggesting that there is a great potential of citrus greening disease detection using an HS image.     

硒在植物抵御胁迫中作用的研究进展

硒是有益于植物生长的微量元素之一,在植物抵御生物胁迫与非生物胁迫中发挥重要作用。从硒在植物中的代谢途径出发,介绍了硒在不同环境胁迫下使植物抗逆性提升的作用机理,综述了硒在植物抵抗生物胁迫与非生物胁迫中的作用,以及硒与其他元素的交互作用,以期为未来硒在农业生态安全领域的研究及应用提供参考。     

Early detection and classification of plant diseases with Support Vector Machines based on hyperspectral reflectance

Automatic methods for an early detection of plant diseases are vital for precision crop protection. The main contribution of this paper is a procedure for the early detection and differentiation of sugar beet diseases based on Support Vector Machines and spectral vegetation indices. The aim was (I) to discriminate diseased from non-diseased sugar beet leaves, (II) to differentiate between the diseases Cercospora leaf spot, leaf rust and powdery mildew, and (III) to identify diseases even before specific symptoms became visible. Hyperspectral data were recorded from healthy leaves and leaves inoculated with the pathogens Cercospora beticola, Uromyces betae or Erysiphe betae causing Cercospora leaf spot, sugar beet rust and powdery mildew, respectively for a period of 21 days after inoculation. Nine spectral vegetation indices, related to physiological parameters were used as features for an automatic classification. Early differentiation between healthy and inoculated plants as well as among specific diseases can be achieved by a Support Vector Machine with a radial basis function as kernel.The discrimination between healthy sugar beet leaves and diseased leaves resulted in classification accuracies up to 97%. The multiple classification between healthy leaves and leaves with symptoms of the three diseases still achieved an accuracy higher than 86%. Furthermore the potential of presymptomatic detection of the plant diseases was demonstrated. Depending on the type and stage of disease the classification accuracy was between 65% and 90%.     

Using optimal combination method and in situ hyperspectral measurements to estimate leaf nitrogen concentration in barley

Leaf nitrogen concentration (LNC), a good indicator of nitrogen (N) status in crops, is of special significance to diagnose nutrient stress and guide N fertilization in fields. Due to non-destructive and quick detectability, hyperspectral remote sensing plays a unique role in detecting LNC in crops. Barley, especially malting barley, is very demanding for N nutrition and requires timely monitoring and accurate estimation of N concentration in barley leaves. Hyperspectral techniques can help make effective diagnosis and facilitate dynamic regulation of plant N status. In this study, canopy reflectance spectra (between 350 and 1 050 nm) from 38 typical barley fields were measured as well as the corresponding LNC in Hailar Nongken, China’s Inner Mongolia Autonomous Region in July, 2010. Existing spectral indices that are considered to be good indicators for assessing N status in crops were selected to estimate LNC in barley. In addition, the optimal combination (OC) method was tested to extract the sensitive indices and first-order spectral derivative wavebands that are responsible for variation of leaf N in barley, and expected to develop some combination models for improving the accuracy of LNC estimates. The results showed that most of the selected indices (such as NPCI, PRI and DCNI) could adequately describe the dynamic changes of LNC in barley. The combined models based on OC performed better in comparison with the individual models using either spectral indices or first-order derivatives and the other methods (such as PCA). A combined model that integrated the first-order derivatives from five wavebands with OC performed well with R ² of 0.82 and RMSE of 0.50 for LNC in barley. This good correlation with ground measurements indicates that hyperspectral reflectance and the OC method have good potential for assessing N status in barley.     

MATE转运蛋白在水稻抗逆作用中的研究进展

水稻 Oryzasativa在生长发育过程中需要面对自然环境中多重不利因素的影响,包括非生物胁迫和生物胁迫。为了抵御这些不利因子,水稻在自然选择过程中形成了多种机制以保护植株的健康生长。多药物有毒化合物排出家族转运蛋白（Multidrug and toxic compound extrusion family ,MATE family）是植物体中一类新型大家族蛋白,它们在细胞的解毒机制中起重要作用。本文介绍了MATE蛋白的基本特征、分子机制和生物学功能以及目前在水稻抗逆作用中的研究概况,以期为水稻抗胁迫研究提供新的思路和理论参考。     

外源物质在植物抗逆中的应用研究进展

从应用外源物质来提高植物抗逆性入手,综述了国内外应用外源物质来提高植物抵抗非生物逆境、生物逆境的能力,并总结分析了诱导抗性产生的生理生化机理.     

植物抗逆相关ERF转录因子研究综述

植物在它的生命周期中要经历各种逆境胁迫。植物许多胁迫相关基因的表达主要受特定转录因子在转录水平的调控。ERF转录因子家族参与植物的生物胁迫和非生物胁迫的应答,是同植物抗逆应答密切相关的一类转录因子大家族。它们通过识别不同的顺式元件,调节多种功能基因的表达,调节植物抗性应答。综述简要介绍ERF转录因子及其相关顺式作用元件。阐述植物ERF转录因子家族在植物抗逆应答中的功能。     

内生真菌对植物生长发育的影响

对内生真菌作用于植物生长发育的影响进行了综述,包括内生真菌促进植物生长的作用机制、对种子萌发的作用、增强植物对生物与非生物的抗逆性、对植物活性次生代谢产物积累的影响等,对植物资源的开发与保护、珍稀活性成分的生产等有着重要的意义。     

基于高光谱成像技术的菊花花色表型和色素成分分析

为无损、高效测定菊花花色表型和色素成分及含量,以菊花160个品种为研究材料,用紫外分光光度法测定舌状花的色素种类和含量;用高光谱成像技术对菊花不同品种头状花序上不同花轮位置上舌状花不同部位的高光谱反射值进行测定;对高光谱反射指数与舌状花色素含量实测值间的相关性进行分析。结果表明:1)菊花头状花序中轮的舌状花正面的中部或偏后部获得的高光谱测定数据稳定。2)菊花相同色系品种具有相似的高光谱特征曲线,不同色系品种高光谱特征曲线存在差异。3)高光谱反射指数RRed/RGreen、ARI、mARI、mCRI、TCARI与菊花舌状花色素含量之间有较好的相关性,并利用80个品种分别建立了色素成分及含量监测模型。4)利用另外80个菊花品种进行验证发现,以RRed/RGreen、ARI和mARI建立的花青素含量监测模型、mCRI建立的类胡萝卜素含量监测模型和TCARI建立的叶绿素含量监测模型精度较高,可以无损、快速地测定菊花舌状花色素成分和含量。本研究为观赏植物花色表型分析和色素成分及含量的测定提供了一种新的思路和方法。      

硫化氢在植物中抵御非生物胁迫机制的研究进展

植物在生长发育过程中不可避免地受到各种生物或非生物胁迫。硫化氢(H2S)作为一种细胞信号分子,在植物体抵御冷热、重金属、盐、干旱等各种非生物逆境胁迫及与其他信号物质的互作等方面发挥重要作用。综述了H2S在植物体中通过基因调控、改变酶活性和蛋白质的表达、硫巯基化修饰、减轻氧化应激、与信号物质的互作等抵御非生物胁迫的作用机制,并展望了H2S在植物体中抵御非生物胁迫的作用机制。     

AP2/ERF蛋白调控植物的非生物胁迫应答机制

AP2/ERF蛋白是植物所特有的转录因子,参与植物生长发育以及调控生物和非生物胁迫反应。研究表明,AP2/ERF蛋白不仅与其它类型转录因子共同形成复杂的转录调控网络,通过多种信号转导途径调控功能基因的表达,而且可以作为外界信号的感应因子调控植物的非生物胁迫应答。主要从AP2/ERF蛋白在植物激素合成、蜡质合成、低氧胁迫应答、ROS清除以及蛋白质修饰等方面综述了AP2/ERF蛋白在植物非生物胁迫应答中的研究进展,并展望了今后的研究方向。     

作物环境胁迫高光谱遥感监测研究进展

作物环境胁迫频发不仅严重影响区域粮食生产和生态安全,还威胁社会经济稳定和可持续发展,高光谱遥感可实时、准确监测作物环境胁迫,与传统监测方法相比具有较大优势。首先阐述了高光谱遥感监测作物环境胁迫的理论基础,重点从基于光谱响应特征的直接监测、基于农学参数和生理信息反演的间接监测两方面,概述了高光谱遥感在监测作物病虫害、水分胁迫方面的研究进展。在此基础上,提出了目前该技术在作物环境胁迫监测应用领域的不足,如光谱响应特征的专属性认识不足、反演模型的精度及普适性较低、数据使用受到限制等,并讨论了高光谱遥感在作物环境胁迫监测方面的发展方向,旨在为农作物环境胁迫监测及预警提供参考。     

番茄WRKY基因的克隆与分析

WRKY转录因子可调控下游抗逆基因的表达,进而在植物生物和非生物胁迫中起重要作用。以水杨酸诱导的番茄为材料,设计简并引物后进行RT-PCR扩增,得到4个含有WRKY结构域的EST。选择其中之一,采用同源克隆的方法扩增出WRKY基因的全长。半定量PCR分析结果表明,400 mmol/L NaCl、4℃低温胁迫后该基因表达量发生变化,说明其可能与番茄的耐盐性和耐低温性有关。     

蛋白质组学在大豆中的研究进展

蛋白质组学分析是目前分离、鉴定蛋白差异表达最为有效的研究手段之一,其核心技术包括以双向电泳为主的蛋白质分离技术、以质谱分析为核心的蛋白质鉴定技术以及计算机图像数据处理和数据库的构建。蛋白质组学分析方法是功能基因组研究的重要支柱。文章总结了蛋白质组学分析用大豆蛋白提取方法的改进,综述了蛋白质组学技术在大豆与根瘤菌相互作用、大豆组织器官蛋白、生长发育相关蛋白研究上的应用以及在生物及非生物胁迫、细胞器水平、大豆遗传多样性及转基因鉴定领域的研究进展,同时对大豆蛋白质组学的发展前景进行了展望。     

植物WRKY转录因子及其生物学功能研究进展

WRKY转录因子是一个大的植物转录因子家族。该转录因子家族最显著的特征是家族各成员至少包含一个WRKY结构域,该结构域的N-端有一个高度保守的WRKYGQK基序,C-端为一个锌指类似结构域(zinc-finger-like motif),一般组成为C-X_(4-5)-C-X_(22-23)-H-X-H。WRKY转录因子通过WRKY结构域与下游目标基因启动子区的W-box进行特异性结合从而调控目标基因的表达。研究表明,WRKY蛋白除了广泛参与植物种子萌发与休眠、叶片衰老、代谢、激素信号转导外,还参与生物和非生物胁迫等生理生化反应过程的调控等新功能。综述了国内外有关WRKY转录因子的研究进展,讨论了其在植物生长发育以及应对生物和非生物胁迫过程中发挥的调控功能,以期为全面研究WRKY转录因子家族的结构和功能提供新的观点。     

植物激素信号传导途径研究进展

植物激素是植物体内合成的微量有机物质,在植物生长发育的各个阶段以及生物和非生物胁迫适应性中都发挥着重要作用。综述了生长素、赤霉素、脱落酸、茉莉酸和乙烯五种激素信号传导途径及其在植物生长发育中的相互作用等方面取得的最新研究进展,以期为激素的理论和应用研究提供参考。