Morphologic and taxonomic relationships of the Psilotaceae relative to evolutionary lines in early land vascular plants

Examination of the fossil record shows that there is no direct evidence regarding the origins and early evolution of the Psilotaceae. Past comparisons betweenPsilotum orTmesipteris and certain fossil plants are reviewed. The major types of early land vascular plants are surveyed in order to demonstrate their basic characteristics and evolutionary trends and to point out the absence of any direct links with the Psilotaceae. Fossil plants of problematical affinities which appear to be important in the early diversification of ferns or plants closely related to ferns are discussed. The nature of stem-leaf relationships of some primitive, extant filicalean ferns and possibly the Psilotaceae is considered in terms of possible similar occurrences among fossil plants.     

Insights into the cellular mechanisms of desiccation tolerance among angiosperm resurrection plant species

Water is a major limiting factor in growth and reproduction in plants. The ability of tissues to survive desiccation is commonly found in seeds or pollen but rarely present in vegetative tissues. Resurrection plants are remarkable as they can tolerate almost complete water loss from their vegetative tissues such as leaves and roots. Metabolism is shut down as they dehydrate and the plants become apparently lifeless. Upon rehydration these plants recover full metabolic competence and ‘resurrect’. In order to cope with desiccation, resurrection plants have to overcome a number of stresses as water is lost from the cells, among them oxidative stress, destabilization or loss of membrane integrity and mechanical stress. This review will mainly focus on the effect of dehydration in angiosperm resurrection plants and some of the strategies developed by these plants to tolerate desiccation. Resurrection plants are important experimental models and understanding the physiological and molecular aspects of their desiccation tolerance is of great interest for developing drought‐tolerant crop species adapted to semi‐arid areas.     

熊果酸抗肿瘤和抗心血管疾病作用的研究进展

熊果酸（ursolic cid,UA）属三萜类化合物,是许多中药复方的主要有效成分之一。它具有抗肿瘤、抗糖尿病、降脂、抗炎、抗氧化等多种生物学效应。本文就UA对肿瘤细胞增殖信号通路的影响和抗心血管疾病作用研究进展方面进行综述,以期为UA的开发提供新思路。     

Let it bloom: cross-talk between light and flowering signaling in Arabidopsis

The terrestrial environment is complex, with many parameters fluctuating on daily and seasonal basis. Plants, in particular, have developed complex sensory and signaling networks to extract and integrate information about their surroundings in order to maximize their fitness and mitigate some of the detrimental effects of their sessile lifestyles. Light and temperature each provide crucial insights on the surrounding environment and, in combination, allow plants to appropriately develop, grow and adapt. Cross-talk between light and temperature signaling cascades allows plants to time key developmental decisions to ensure they are ‘in sync’ with their environment. In this review, we discuss the major players that regulate light and temperature signaling, and the cross-talk between them, in reference to a crucial developmental decision faced by plants: to bloom or not to bloom?     

梯级电站建设对勐乃河流域生物多样性的影响分析

综合运用地理信息系统(GIS)和遥感(RS)技术,分析了勐乃河梯级电站建设对流域内景观多样性、流域内铜壁关自然保护区(昔马片)的主要保护植被类型—龙脑香林和保护区内的珍稀濒危动植物造成的影响。结果表明,梯级电站的建设,将会加剧勐乃河流域景观的破碎化程度,改变流域的景观多样性,但对景观层次影响不大;而工程建设对保护区内的龙脑香林和珍稀濒危动植物的影响却不容忽视,尤其是道路的建设,将导致流域内森林覆盖率下降5.83%,森林面积减少1472.09hm2,其中69.1hm2的龙脑香林受到不同程度的影响。为了最大限度地降低工程建设对生物多样性造成的影响,针对本项工程的特点,文章从五个方面提出了相应的建议和措施。     

麦圆蜘蛛在麦株上的转移习性观察

麦圆蜘蛛Penthaleus major(Duges)在小麦上的危害有明显加重的趋势,田间种群密度的调查仍是目前虫情测报的主要手段。为了解麦圆蜘蛛在麦株上的转移习性,以便为其田间调查取样和防治提供参考,作者于2008年进行3部分田间观察。结果表明:麦圆蜘蛛在小麦植株上具有较强的活动性,可随田间环境条件的不同而改变其栖息场所。在同一观察日内,其在麦株上的虫量多表现早晚时段多于中午时段;在有风、阴雨和气温相对较高时,麦株上的虫量分布均有明显下降的趋势。麦圆蜘蛛主要分布于麦株由上向下数第3～4叶位上;在不同叶位上的虫量,多以叶片反面相对最多,其次为叶鞘和叶片正面。     

Evolution of photoprotection mechanisms upon land colonization: evidence of PSBS‐dependent NPQ in late Streptophyte algae

Light is the energy source for photosynthetic organisms but, if absorbed in excess, it can drive to the formation of reactive oxygen species and photoinhibition. One major mechanism to avoid oxidative damage in plants and algae is the dissipation of excess excitation energy as heat, called non‐photochemical quenching (NPQ). Eukaryotic algae and plants, however, rely on two different proteins for NPQ activation, the former mainly depending on LHCSR (Lhc‐like protein Stress Related; previously called Li818, Light Induced protein 818), whereas in the latter the major role is played by a distinct protein, PSBS (photosystem II subunit S). In the moss Physcomitrella patens, which diverged from vascular plants early after land colonization, both these proteins were found to be present and active in inducing NPQ, suggesting that during plants evolution both mechanisms co‐existed. In order to investigate in more detail NPQ adaptation toward land colonization, we analyzed Streptophyte algae, the latest organisms to diverge from the land plants ancestors. Among them we found evidence of a PSBS‐dependent NPQ in species belonging to Charales, Coleochaetales and Zygnematales, the latest groups to diverge from land plants ancestors. On the contrary earlier diverging algae, as Mesostigmatales and Klebsormidiales, likely rely on LHCSR for their NPQ activation. Presented evidence thus suggests that PSBS‐dependent NPQ, although possibly present in some Chlorophyta, was stably acquired in the Cambrian period about 500 million years ago, before late Streptophyte algae diverged from plants ancestors.     

SUMMARY OF GREEN PLANT PHYLOGENY AND CLASSIFICATION

Abstract— A cladogram of green plants involving all major extant groups of green algae, bryophytes, pteridophytes, and seed plants is presented. It is partly based on contributions by B. Mishler and S. Churchill, H. Wagner, and P. Crane. The relationships of green plants to other green organisms ( Prochloron , euglenophytes) are discussed. The characters and subclades of the cladogram are briefly discussed, with an attempt to indicate weak points. The possibility of including some major extinct groups is considered. A cladistic classification consistent with the cladogram is presented. Grades are abandoned as taxa and major clades like the division Chlorophyta (green algae excluding micro-monadophytes and charophytes sensu Mattox and Stewart), the division Streptophyta (charophytes + embryophytes), the subdivision Embryophytina (land plants or embryophytes), the superclass Tracheidatae (tracheophytes), and the class Spermatopsida (seed plants) are recognized.     

黄河中游河漫滩(禹渡口-桃花峪)种子植物资源

黄河中游河漫滩有种子植物84科、358属、818种,根据用途资源植物种类有56科270种,可划分为有6类、25亚类.其中含种数较多的依次为:纤维植物类、饲用植物类、药用植物类、抗污染植物类、指示植物类、水土保持植物类.文章分析了该区域的主要资源植物特点,并对资源植物的开发利用和保护提出了建议.     

西双版纳热带植物园引种植物个体适应性研究

本研究通过比较引种植物和本土植物的生长状况,主要是果熟现象,讨论了引种植物对引种目的地的适应性。中国科学院西双版纳热带植物园,引种和保存了国内外万种以上的热带和亚热带植物,并对多种引种植物进行了长期连续生长监测。本文统计分析了其中观测4年以上的569个编号的引种植物生长适应状况。结果表明：1）引种植物基本适应植物园的环境,但是不同气候区来源的植物适应性表现不同,不同地区来源植物适应性顺序为：热带亚洲植物〉亚热带和热带北缘植物／热带非洲植物〉热带澳洲植物〉热带美洲植物;2）不同科属植物个体适应表现也有差别,无患子科,蝶形花科,楝科和紫葳科等的植物个体适应性和本土植物比较相似,而大戟科植物个体适应性和本土植物差异最大;3）分析表明引种植物对植物园的适应受到来源地气候和区系起源两个因素的影响;4）紫蒇科,桃金娘科和含羞草科的一些引种植物个体果熟年比高于本土植物,其入侵性有待于进一步入评估。     

Development and deployment of transgenic plants: Biosafety considerations

Summary Recombinant DNA technology has great potential to enhance and extend the advantages of conventional plant breeding, and increase the production and productivity of crops to meet the increasing demand for food and food products in the future. Judicious application of this technology provides opportunities for alleviating some of the major constraints to crop productivity under subsistence farming conditions in the developing countries. Considerable progress has been made in developing strategies for the production and deployment of transgenic crops. However, biosafety concerns have been raised regarding the deployment and release of genetically engineered plants. This debate has divided the farming and consumer communities over acceptability of genetically modified foods. There is a need for a thorough investigation regarding the fate of transgenic plants in the environment, and their interaction with wild relatives and non-target organisms. The production and release of transgenic plants should be based on experience and sound scientific reasoning. The regulatory requirements for deployment of transgenic crops should be streamlined and harmonized, in order to achieve sustainable food production, poverty reduction, and environmental protection in resource-poor countries in the semi-arid tropics.     

Glutathione conjugates in the vacuole are degraded by gamma-glutamyl transpeptidase GGT3 in Arabidopsis

gamma-Glutamyl transpeptidase (GGT) is the enzyme responsible for breaking the gamma-glutamyl bond between Glu and Cys in glutathione (GSH). We are using this gene family to study GSH degradation in plants. There are four putative GGT genes in Arabidopsis, and one of them, GGT3 (At4g29210), is analyzed in this study. GGT3 is localized to the vacuole based on organelle-targeting programs, subcellular distribution of GFP fusion proteins during transient expression in onion (Allium cepa) epidermal tissues, and its ability to metabolize vacuolar substrates in Arabidopsis plants. While Northern blots and promoter:GUS expression patterns have suggested that GGT3 is transcribed at relatively high levels in all parts of the plant, a comparison of enzyme activities in different organs of wild-type and a ggt3 knockout mutant showed that GGT3 was a major contributor to total GGT activity in roots, but a relatively minor contributor in other tissues. Wild-type Arabidopsis plants treated with monobromobimane (mBB) form a fluorescent GSH-mBB conjugate that is moved into the vacuole and then metabolized to Cys-Gly-mBB and Cys-mBB in that order. The first step is catalyzed by GGT3, and GSH-mBB metabolism is completely blocked in the roots of ggt3 knockout plants. In ggt3 leaves, some GSH-mBB metabolism still proceeds using the apoplastic GGT1. This identifies GGT3 as catalyzing the obligate initial step in GSH conjugate metabolism, and suggests that it has an important role in protecting plants from some xenobiotic chemicals.     

Synthetic capacity of Arabidopsis phosphatidylinositol synthase 1 expressed in Escherichia coli

Phosphatidylinositol (PtdIns) synthase 1 from the plant Arabidopsis thaliana has been expressed in Escherichia coli in order to study the synthetic capacities of the enzyme. Analysis of the total fatty acid content of the bacteria shows that PtdIns synthase activity does not have a profound effect on the proportions of the different fatty acids produced, even if the presence of an extra acidic phospholipid leads to a global reduction of the lipid content. A closer analysis carried out on individual phospholipids reveals a global fatty acid composition almost unchanged in the two major bacterial lipids phosphatidylethanolamine (PtdEtn) and phosphatidylglycerol (PtdGro). Phosphatidylinositol has a very unusual composition that shows the ability of the plant enzyme to use CDP-diacylglycerol molecular species absent from plants. We identified the various PtdIns molecular species. They represent a pool of the major molecular species of PtdEtn and PtdGro. These results, together with the determination of the apparent affinity constants of AtPIS1 for myo-inositol and CDP-diacylglycerol, allow us to discuss some of the constraints of PtdIns synthesis in plants in terms of specificity, which will depend on the subcellular localization of the protein.     

Identification of novel and conserved microRNAs in Coffea canephora and Coffea arabica

As microRNAs (miRNAs) are important regulators of many biological processes, a series of small RNAomes from plants have been produced in the last decade. However, miRNA data from several groups of plants are still lacking, including some economically important crops. Here microRNAs from Coffea canephora leaves were profiled and 58 unique sequences belonging to 33 families were found, including two novel microRNAs that have never been described before in plants. Some of the microRNA sequences were also identified in Coffea arabica that, together with C. canephora, correspond to the two major sources of coffee production in the world. The targets of almost all miRNAs were also predicted on coffee expressed sequences. This is the first report of novel miRNAs in the genus Coffea, and also the first in the plant order Gentianales. The data obtained establishes the basis for the understanding of the complex miRNA-target network on those two important crops.     

Pollination: the price of attraction

Nectar is the major currency bringing together plants and pollinators; yet the costs and benefits of nectar production remain poorly understood. A low nectar line developed in Petunia offers an innovative approach to this problem and may offer clues to why some plants cheat and secure pollination via deception.     

Melatonin and TiO2 NPs Application-Induced Changes in Growth,Photosynthesis, Antioxidant Enzymes Activities and Secondary Metabolites in Stevia (Stevia rebaudiana Bertoni) Under Drought Stress Conditions

Journal of Plant Growth Regulation - Drought stress is one of the major constraints on the growth and productivity of crop plants. Recently, new approaches have been employed in order to cope with...     

Role of Phytohormones in Sex Differentiation in Plants

The role of phytohormones in sex expression in plants is briefly surveyed. The interaction of hereditary and environmental factors in sex expression is considered. A major role of gibberellins and cytokinins in the regulation of sex expression in dioecious and monoecious flowering plants and in some muscoids is demonstrated. The evidence for the effect of other phytohormones and physiologically active compounds on sex expression in plants is examined.     

泉州植物区系的特征与保护

泉州植物区系种类丰富,起源古老,子遗植物和单种的科、属植物较多,特有现象明显,植物区系地理成分以热带、亚热带分布的科、属占优势。对泉州的资源植物必须加以保护和合理开发利用。     

渗透胁迫调节的转基因表达对植物抗旱耐盐性的影响

干旱和盐渍是影响植物生长和农作物产量的最重要的环境因子,本文综述了近年来通过超量表达低分子量化合物和渗透肋迫保护蛋白等获得抗旱耐盐转基因植物的报道,旨在系统阐述转基因表达对植物抗旱耐盐性的影响。     

渗透胁迫调节的转基因表达对植物抗旱耐盐性的影响

干旱和盐渍是影响植物生长和农作物产量的最重要的环境因子。本文综述了近年来通过超量表达低分子量化合物和渗透胁迫保护蛋白等获得抗旱耐盐转基因植物的报道,旨在系统阐述转基因表达对植物抗旱耐盐性的影响。