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关键词： catalyze   plant   deconstruction   biochemistry   Monosaccharides   Cell wall   Structure-function relationships   structural biology   Biological   Enzymes   wall   Catalysis   Glycoside Hydrolases   Polysaccharides   Lyases   Explosions  

摘要： The cell walls of plants are the most abundant source of organic carbon on the planet. This photosynthetically fixed carbon is recycled by microbial enzymes that convert cell wall polysaccharides to monosaccharides and oligosaccharides, a process that is of biological and industrial importance (Sticklen, 2008; Himmel and Bayer, 2009). Plant cell walls are recalcitrant to biological depolymerization, as the extensive interactions between polysaccharides, and between polysaccharides and lignin, restrict access to the battery of microbial glycoside hydrolases, pectate lyases, and esterases that breakdown these composite structures (for review, see Mohnen, 2008). Since the early 1990s, there has been an explosion of structural information on both the catalytic and noncatalytic components of these enzymes. This review will provide an overview/update of the structure-function relationships of the enzymes that catalyze plant cell wall deconstruction.

关键词： PHYTOPATHOGENIC microorganisms   PHYTOPATHOGENIC fungi   OOMYCETES   NATURAL immunity   PARASITIC diseases   PROTEINS  

摘要： P>Filamentous pathogens, such as plant pathogenic fungi and oomycetes, secrete an arsenal of effector molecules that modulate host innate immunity and enable parasitic infection. It is now well accepted that these effectors are key pathogenicity determinants that enable parasitic infection. In this review, we report on the most interesting features of a representative set of filamentous pathogen effectors and highlight recent findings. We also list and describe all the linear motifs reported to date in filamentous pathogen effector proteins. Some of these motifs appear to define domains that mediate translocation inside host cells.

关键词： Taxonomy   Pollination   Seed germination   Asclepias curassavica L.   Clerodendrum viscosum Vent   Scoparia dulcis L  

摘要： This paper presents the flower morphology, pollination mechanisms and seed germination of three indigenous medicinal plants of Bangladesh namely, Asclepias curassavica L., Clerodendrum viscosum Vent and Scoparia dulcis L. The minimum days taken for seed germination in Asclepias curassavica, Clerodendrum viscosum and Scoparia dulcis are 6, 14 and 9, respectively Epigeal type of seed germination has been noted in Asclepias curassavica and Scoparia dulcis, whereas hypogeal type of seed germination has been found in Clerodendrum viscosum Fruit production is highest in Scoparia dulcis among the species studied and a maximum of 304 seeds are produced per fruit in it. Maximum 108 seeds are produced per fruit in Asclepias curassavica Among the species investigated Asclepias curassavica and Clerodendrum viscosum are cross-pollinated, and Scoparia dulcis is self-pollinated Butterflies, bees and ants are noted to be the pollinators in Asclepias curassavica and in Clerodendrum vacosum black ants. butterflies and long tongue hawk moths are the pollinators

关键词： 砷   根际   吸收运输   超积累植物   微生物  

摘要： 砷既是抗癌药物,也是致癌物质。砷不但会对植物造成毒害,并且能够通过食物链进入人体和动物体,对其造成伤害。近年来包括我国在内的世界上许多国家发生的砷中毒事件,引起了公众的极大关注,促使各国科学家致力于砷从环境进入植物体的过程和机理研究。本文从土壤砷、根际砷、植物对砷的吸收和运输,以及植物耐砷机理和微生物在植物抗砷过程中的作用这五个方面,概括了砷从土壤到植物根际并进入植物体的过程,植物抗砷的生理分子机制以及微生物与植物抗砷的研究进展。并对将植物耐砷机理运用到作物上,以及利用砷超积累植物清除环境中的砷做了展望。

关键词： 分子生物学技术   苔藓植物   系统分类  

摘要： 经典苔藓植物系统分类研究在科属划分、系统位置等方面存在较大争议，分子生物学技术应用于苔藓植物系统分类研究是对经典分类研究的重要补充。应用在苔藓系统分类研究中的分子生物学技术主要包括DNA序列分析技术随机扩增多态性DNA（RAPD）、限翩性片段长度多态性（RFLP）技术和同工酶分析技术等。基于分子生物学技术的苔藓分子系统学与经典分类学相结合，将为苔藓植物系统演化、科属地位划分、物种鉴定等研究提供更多的可靠证据。

关键词： 木本植物   分子生物学   DNA分子标记   转基因技术  

摘要： 从DNA分子标记技术和转基因技术两方面,对国内外木本植物分子生物学研究进展进行了简要综述,并就该领域分子生物学研究中亟需解决的问题和应用前景进行了讨论。

关键词： 樟科   黄绒润楠   柳叶润楠   传粉生物学   繁育系统   雌雄异熟   雌雄异位  

摘要： 本文对樟科润楠属（Machilus Nees）黄绒润楠（*** Hance）和柳叶润楠（*** Hance）进行了传粉生物学的比较研究，结果发现这两种植物具有相似的花部结构，但开花生物学特性和传粉机制存在较大差异。\n 黄绒润楠单花花期2-3 d，整个开放过程经历开放、闭合、再次开放三个阶段，同时整个开放过程中雌雄蕊位置关系不断变化，表现为动态式雌雄异位。第一次开放时，内外轮雄蕊与花被片一起展开，花药不开裂、柱头具有可受性为雌性阶段，该阶段持续约6-12 h；中间闭合阶段，持续约6-12 h；二次开放时，仅外轮雄蕊与花被片一起展开，内轮雄蕊紧靠花柱不再打开，此阶段柱头变色、花药开裂为雄性阶段，持续约24-36 h。整个居群全天均有花开，全株花开放不同步，且植株间开花方式无差异。内外轮雄蕊在花粉量、活性、花粉大小及形态方面并无显著差异，但是内轮花药的花粉更易散发。蜜蜂（Apis sp.）和熊蜂（Bombus sp.）是其有效传粉者，报酬物为花粉和花蜜；繁育系统检测表明，黄绒润楠自然结实率较低，且存在一定程度的自交衰退，为混合交配类型。该植物这种花内雌雄异熟及雌雄异位可以有效的避免花内性别干扰，促进异交，但并不能避免同株异花授粉。\n 柳叶润楠具有与黄绒润楠相似的开花过程（雌花阶段、中间闭合阶段和雄花阶段），但在白天气温18℃以上时，整个居群植株表现为两种类型：早上花植株和中午花植株。早上花植株花在早上约8:00-8:30第一次开放，雌花阶段持续至约12:00闭合，闭合持续至第二天约13:00再次开放，第二次展开为雄花阶段并持续至约18:00再次闭合，萎谢。中午花植株花在中午约12:30-13:00第一次开放，雌花阶段持续至约18:00闭合，闭合持续至第二天早上约7:00再次开放，第二次展开为雄花阶段并持续至约12:00再次闭合，萎谢。柳叶润楠这种严格的同步雌雄异熟机制，可以有效的避免自花授粉和同株异花授粉的发生。结果表明两型植株在花部结构、花粉胚珠比、繁育系统检测等方面无显著差异。当气温较低时这种严格的同步性会被打破，整个居群开花呈无序状态。蜜蜂（Apidae sp.）、马蜂（Polostes sp.）是其有效传粉者，报酬物为花粉和花蜜。繁育系统检测表明，柳叶润楠自然结实率较低，自交与异交结实率差异不显著。

关键词： 传粉生物学   繁育系统   姜花属   距药姜属  

摘要： 对姜科距药姜属（Cautleya）的距药姜（***）和红苞距药姜（***）及姜花属（Hedychium）的草果药（***）和疏花草果药（*** ***）四种植物的传粉生物学进行了比较研究，发现这四种植物具有多样的传粉机制。\n 红苞距药姜单花花期1天。人工授粉实验结果显示，自然状态下座果率较高，开花前套袋不结实，说明自然状态下不能主动自交，需要接受外源花粉。实验结果显示，红苞距药姜的杠杆状雄蕊在传粉过程中起到关键作用。花药附属物--距、花药和花丝组成杠杆结构，当昆虫访花时，推动距使花药倒扣在昆虫背部，花粉散落到昆虫背部传播出去；同时位于花药前端的柱头也接触到昆虫背部，接受花粉。距药姜单花花期同样也为1天。人工授粉实验结果显示，自然状态和开花前套袋座果率都较高，说明自然状态下能主动自交。距药姜虽然也有相同的杠杆结构，但是其柱头位于花药两个花粉囊中间，在花药刚开裂时自身花粉就会与柱头接触，实现自交。距药姜柱头位置的变化，使其传粉机制实现了根本改变。通过形态结构对比可以推断距药姜的主动自交是由与红苞距药姜相类似的虫媒异交传粉机制演化而来。\n 草果药和疏花草果药生长在同一生境，它们具有相同的传粉机制。通过单花观察发现，草果药和疏花草果药花期4天，它们在开花后第一天内，花丝和花柱仍然进行伸长生长，但是花丝生长速度快于花柱，导致柱头与花药的位置关系发生变化：花刚打开时柱头在花药顶端，到第二天柱头运动到花药中间位置，并且与花药接触。两种植物完全套袋处理的繁育系统检测均结实，因此草果药和疏花草果药具有一种主动自交传粉机制，有别于姜花属中其它种的蛾类传粉机制。

关键词： Ascorbate   Glutathione   NAD(P)H   Stress   Redox signalling   Redox state   Thioredoxin  

摘要： Different redox-active compounds, such as ascorbate, glutathione, NAD(P)H and proteins from the thioredoxin superfamily, contribute to the general redox homeostasis in the plant cell. The myriad of interactions between redox-active compounds, and the effect of environmental parameters on them, has been encapsulated in the concept of a cellular redox state. This concept has facilitated progress in understanding stress signalling and defence in plants. However, despite the proven usefulness of the concept of a redox state, there is no single, operational definition that allows for quantitative analysis and hypothesis testing. (C) 2010 Elsevier Masson SAS. All rights reserved.

关键词： Darwin   germination   microRNA   seeds   stress response  

摘要： microRNAs (miRNAs) are small, single-stranded RNAs that down-regulate target genes at the post-transcriptional level. miRNAs regulate target genes by guiding mRNA cleavage or by repressing translation. miRNAs play crucial roles in a broad range of developmental processes in plants. Multiple miRNAs are present in germinating seeds and seedlings of Arabidopsis, some of which are involved in the regulation of germination and seedling growth by plant hormones such as abscisic acid (ABA) and auxin. The involvement of miRNAs in ABA responses is not limited to the early stages of plant development but seems to be important for general stress responses throughout the plant life cycle. This Darwin review summarizes recent progress in miRNA research focusing on seed and stress biology, two topics which were of interest to Charles Darwin.