Functional coordination between branch hydraulic properties and leaf functional traits in miombo woodlands: implications for water stress management and species habitat preference

We investigated functional coordination between branch hydraulic properties and leaf functional traits among nine miombo woodlands canopy tree species differing in habitat preference and phenology. Specifically, we were seeking to answer the question: are branch hydraulic properties coordinated with leaf functional traits linked to plant drought tolerance in seasonally dry tropical forests and what are the implications for species habitat preference? The hydraulic properties investigated in this study were stem area specific hydraulic conductivity (K _S), Huber value (H _v), and xylem cavitation vulnerability (??₅₀). The leaf functional traits measured were specific leaf area (SLA), leaf dry matter content (LDMC), and mean leaf area (MLA). Generalists displayed significantly (P?<?0.05) higher cavitation resistance (??₅₀) and SLA, but lower sapwood specific hydraulic conductivity (K _S), leaf specific conductivity (K _L), MLA, and LDMC than mesic specialists. Although MLA was uncorrelated with ??₅₀, we found significant (P?<?0.05) positive and negative correlations between plant hydraulic properties and leaf functional traits linked to plant drought tolerance ability, indicating that the interactions between branch hydraulics and leaf functional traits related to plant drought tolerance ability may influence tree species habitat preference in water-limited ecosystems.     

Synthesis of Hoodigogenin A, aglycone of natural appetite suppressant glycosteroids extracted from Hoodia gordonii

14β-hydroxy pregnane glycosides extracted from Hoodia gordonii, a succulent plant isolated from Apocynaceae are suggested to have appetite suppressant properties in animals and humans. However, limited reports on biological studies concerning the appetite suppressant properties are available in the open literature. One reason for that is the poor availability of these glycosteroids because H. gordonii is a protected plant and the yield of extraction lies between 0.003% and 0.02%. Starting from 3α,12α-diacetoxy-pregnanone 1, we disclose in this report the synthesis of Hoodigogenin A, the aglycone of the natural 14β-hydroxy pregnane glycosides extracted from H. Gordonii.     

Plant growth promoting potential of endophytic bacteria isolated from Piper nigrum

Piper nigrum is an interesting plant to study the endophytic microbial factors affecting plant growth because of its unique features. Endophytic bacterial isolation from the plant resulted in the isolation of twelve bacterial isolates which were screened for various plant growth promoting properties like phosphate solubilization, ACC deaminase production, siderophore production etc. Interestingly, seven isolates were found to have IAA biosynthetic potential. Bacterial isolates with multiple plant growth promoting properties were studied for their growth promoting effect on Vigna radiata seedlings. This resulted in the identification of Klebsiella sp. (PnB 10) and Enterobacter sp. (PnB 11) as the isolates with excellent growth promoting properties. The results confirm promising applications of the endophytic bacterial isolates obtained in the study and also their possible growth promoting effect in P. nigrum.     

Bakkenolide-A. Its distribution in Petasites species and cytotoxic properties

A rapid GLC method is described for the determination of bakkenolide-A in small amounts of plant material. The distribution of bakkenolide-A among the different lipid classes of Petasites albus is discussed and also the distribution among different parts of the plant during a growing season. Smaller amounts of bakkenolide-A are found in P. hybridus buds and only trace amounts in P. fragrans.Cytotoxicity tests showed bakkenolide-A has marked cytotoxic activity and potential anti-tumour properties.     

Multiplex PCR assay for detection of human interferon alpha2b gene in transgenic plants

During the last decade interferons are regarded as potent candidates for generation of plant-based edible vaccines because of broad spectrum of antiviral activities and adjuvant properties. Establishment and certification of numerous interferon producing plant systems requests development of fast and efficient multiplex PCR protocol for the transgene detection in GM plants. Here we represent a protocol for simultaneous amplification in one assay of fragments of hIFN alpha 2b gene and two control genes, namely virD1 of Agrobacterium tumefaciens and conservative region of plant actin gene.     

加拿大一枝黄花入侵对土壤动物群落结构的影响

外来植物对入侵地土壤动物群落及理化性质影响的研究不仅有助于评估入侵植物对生态系统的影响,而且对探索外来植物入侵的土壤动物学响应机制尤为重要。为了了解加拿大一枝黄花对入侵地土壤动物的群落结构及理化性质的影响,本文分季节分层次对加拿大一枝黄花不同程度的入侵地进行取样,获得土壤动物9900个,隶属3门11纲14目,弹尾目和蜱螨类均为优势类群。入侵程度不同的样地中土壤动物个体数量和类群组成不同。土壤动物个体数量和类群数量表现为轻度入侵区＞中度入侵区＞重度入侵区;多样性指数和均匀性指数表现为轻度入侵区＜中度入侵区＜重度入侵区,优势度指数表现与前两指数相反。加拿大一枝黄花的入侵没有改变土壤动物表聚性特点。非度量多维标度排序分析表明,不同入侵程度下的土壤动物分为3类,即轻度入侵类、中度入侵类、重度入侵类。不同入侵区域土壤的pH、有机质含量、铵态氮、速效钾和速效磷差异显著(P＜0.05),土壤的含水量和温度差异不显著(P＞0.05)。灰色关联分析表明,入侵区域土壤铵态氮对土壤动物关联最大,有机质含量次之,再次是速效磷和pH,土壤含水量的影响最小。因而,加拿大一枝黄花的入侵,改变了入侵地土壤理化性质(尤其是对铵态氮的调控),进而改变了土壤动物的群落结构,创造了利于自身生长、竞争有利的土壤环境。     

Trichoderma–Plant–Pathogen Interactions: Advances in Genetics of Biological Control

Trichoderma spp. are widely used in agriculture as biofungicides. Induction of plant defense and mycoparasitism (killing of one fungus by another) are considered to be the most important mechanisms of Trichoderma-mediated biological control. Understanding these mechanisms at the molecular level would help in developing strains with superior biocontrol properties. In this article, we review our current understanding of the genetics of interactions of Trichoderma with plants and plant pathogens.     

Characterization of Squalene synthase Gene from Chlorophytum borivilianum (Sant. and Fernand.)

Saponins are important group of secondary metabolites known for their pharmacological properties. Chlorophytum borivilianum contains high amount of saponins and is thus, recognized as an important medicinal plant with aphrodisiac properties. Though the plant is well known for its pharmaceutical properties, there is meager information available about the genes and enzymes responsible for biosynthesis of saponins from this plant. Squalene synthase (SqS) is the key enzyme of saponin biosynthesis pathway and here, we report cloning and characterization of SqS gene from C. borivilianum. A full-length CbSqS cDNA consisting of 1,760 bp was cloned which contained an open reading frame (ORF) of 1,233 bp, encoding a protein of 411 amino acids. Analysis of deduced amino acid sequence of CbSqS predicted the presence of conserved isoprenoid family domain and catalytic sites. Phylogenetic analysis revealed that CbSqS is closer to Glycine max and monocotyledonous plants. 3D structure prediction using various programs showed CbSqS structure to be similar to SqS from other species. C-terminus truncated recombinant squalene synthase (TruncCbSqS) was expressed in E. coli M15 cells with optimum expression induced with 1 mM IPTG at 37 °C. The gene expression level was analyzed through semi-quantitative RT-PCR and was found to be higher in leaves as compared to the roots.     

Extraction enhancing mechanism of steam exploded Radix Astragali

Plant extraction occupies a vital status in the fine chemical industry, and steam explosion has been confirmed to be an effective pretreatment to enhance the extraction performance. In order to reveal the extraction enhancing mechanism of steam explosion, innovatively from the view of plant porous medium, we characterized porous properties of steam exploded Radix Astragali and established the correlation of porous properties and saponins extraction performance of Radix Astragali. The results indicated that average pore diameter was the most relevant to extraction parameters with R-square > 0.99 among various porous properties, which can effectively characterize the extraction performance. Area percentage of middle and large pores (100–100,000 nm) of Radix Astragali was increased from 8.25% to 91.57% after steam explosion and the increase of these pores was the major factor for enhancing extraction performance. Based on the close correlation of extraction parameters and porous properties, the extraction mechanistic model of steam exploded Radix Astragali was proposed. Altered porous properties improved the solute–solvent accessibility and internal mass transfer in the extraction process. Such findings are anticipated to prompt the enhancing effects and widespread application of steam explosion technology in plant extraction, and further identify research directions that lead to more efficient extraction.     

Nectar properties of the sunbird-pollinated plant Impatiens sakeriana: A comparison with six other co-flowering species

Adaptations of the nectar traits in bird-pollinated flowers are amongst the most discussed aspects of floral evolution. In the case of sunbird-pollinated plants, data on nectar traits originate almost exclusively from the South African region and are very scarce for tropical Africa, where paradoxically the highest sunbird diversity occurs. Here we present a study on the nectar properties of a sunbird-pollinated plant, Impatiens sakeriana, growing in the West African mountains, including the nectar production, diurnal changes in the nectar standing crop, the nectar concentrations, the nectar volumes, total sugar amounts and sugar composition. Moreover we compare the nectar traits of I. sakeriana with six other co-flowering insect-visited plant species.Our results showed that many nectar properties, including high volume (approx. 38 μL in flowers unvisited by sunbirds), low sugar concentration (approx. 30% w/w) and high sucrose content (95%), are specific to I. sakeriana, compared to the insect-visited plants. These are in accordance with the most recent theory that nectar properties of the sunbird-pollinated plants are similar to those pollinated by hummingbirds.     

Benzoxazinoid biosynthesis in dicot plants

Benzoxazinoids are common defence compounds of the grasses and are sporadically found in single species of two unrelated orders of the dicots. In the three dicotyledonous species Aphelandra squarrosa, Consolida orientalis and Lamium galeobdolon the main benzoxazinoid aglucon is 2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA). While benzoxazinoids in Aphelandra squarrosa are restricted to the root, in Consolida orientalis and Lamium galeobdolon DIBOA is found in all above ground organs of the adult plant in concentrations as high as in the seedling of maize. The initial biosynthetic steps in dicots and monocots seem to be identical. Indole is most probably the first specific intermediate that is oxygenated to indolin-2-one by a cytochrome P450 enzyme. C. orientalis has an active indole-3-glycerolphosphate lyase for indole formation that evolved independently from its orthologous function in maize. The properties and evolution of plant indole-3-glycerolphosphate lyases are discussed.     

Characterization of isoflavone synthase gene from Psoralea corylifolia: a medicinal plant

Isoflavones are known to possess medicinal properties and implicated in plant–pathogen interaction. We have for the first time isolated and functionally characterized an isoflavones synthase (IFS) gene from a traditionally acclaimed medicinal plant Psoralea corylifolia abundantly growing in tropical and subtropical regions. The IFS catalyzes the exclusive reaction of phenylpropanoid pathway in leguminous plants to produce isoflavones. The full-length cDNA (PcIFS) of the gene comprised 1,563 bp and putatively encodes a polypeptide of 520 amino acid residues. The gene is expressed ubiquitously although at varying levels in different parts of the plant. The expression analysis suggests that the gene is responsive to methyl jasmonate, salicylic acid and wounding. Overexpression of PcIFS in non-leguminous tobacco plant led to the accumulation of isoflavones in petal tissue, suggesting it a functional gene from P. corylifolia involved in isoflavones biosynthesis.     

Plant Invasions Associated with Change in Root-Zone Microbial Community Structure and Diversity

The importance of plant-microbe associations for the invasion of plant species have not been often tested under field conditions. The research sought to determine patterns of change in microbial communities associated with the establishment of invasive plants with different taxonomic and phenetic traits. Three independent locations in Virginia, USA were selected. One site was invaded by a grass (Microstegium vimineum), another by a shrub (Rhamnus davurica), and the third by a tree (Ailanthus altissima). The native vegetation from these sites was used as reference. 16S rRNA and ITS regions were sequenced to study root-zone bacterial and fungal communities, respectively, in invaded and non-invaded samples and analyzed using Quantitative Insights Into Microbial Ecology (QIIME). Though root-zone microbial community structure initially differed across locations, plant invasion shifted communities in similar ways. Indicator species analysis revealed that Operational Taxonomic Units (OTUs) closely related to Proteobacteria, Acidobacteria, Actinobacteria, and Ascomycota increased in abundance due to plant invasions. The Hyphomonadaceae family in the Rhodobacterales order and ammonia-oxidizing Nitrospirae phylum showed greater relative abundance in the invaded root-zone soils. Hyphomicrobiaceae, another bacterial family within the phyla Proteobacteria increased as a result of plant invasion, but the effect associated most strongly with root-zones of M. vimineum and R. davurica. Functional analysis using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) showed bacteria responsible for nitrogen cycling in soil increased in relative abundance in association with plant invasion. In agreement with phylogenetic and functional analyses, greater turnover of ammonium and nitrate was associated with plant invasion. Overall, bacterial and fungal communities changed congruently across plant invaders, and support the hypothesis that nitrogen cycling bacteria and functions are important factors in plant invasions. Whether the changes in microbial communities are driven by direct plant microbial interactions or a result of plant-driven changes in soil properties remains to be determined.     

Lancea tibetica as the Tibetan herb: A review of its phytochemistry and pharmacology

This review, based on nearly 25 literary sources, discusses the chemical nature and biological effects of the whole plant of Lancea tibetica Hook. f. et Thoms (Scrophulariaceae). Several types of chemical constituents have been isolated from Lancea tibetica (LT) including 34 phenolpropanoids (16 lignans, 5 neolignans, 5 nonanones, 4 phenylpropanoid glycosides, and 4 propanediols), 9 flavones, 6 triterpenoids, and 11 amino acids. Various extracts and individual compounds derived from this species have been determined to possess a variety of pharmacological effects, such as anti-tumour and antioxidant functions. The results of data analysis on the chemical and pharmacological characteristics of LT support the view that this plant has many therapeutic properties, suggesting its potential as an effective herbal remedy. Finally, suggestions for further avenues of research on the chemical and pharmacological properties of LT and ways in which to further exploit LT are presented in this review.     

Plant material features responsible for bamboo's excellent mechanical performance: a comparison of tensile properties of bamboo and spruce at the tissue,fibre and cell wall levels

MethodsThe mechanical properties of single fibres and tissue slices of stems of mature moso bamboo (Phyllostachys pubescens) and spruce (Picea abies) latewood were investigated in microtensile tests. Cell parameters, cellulose microfibril angles and chemical composition were determined using light and electron microscopy, wide-angle X-ray scattering and confocal Raman microscopy.ConclusionsThe superior tensile properties of bamboo fibres and fibre bundles are mainly a result of amplified cell wall formation, leading to a densely packed tissue, rather than being based on specific cell wall properties. The material optimization towards extremely compact fibres with a multi-lamellar cell wall in bamboo might be a result of a plant growth strategy that compensates for the lack of secondary thickening growth at the tissue level, which is not only favourable for the biomechanics of the plant but is also increasingly utilized in terms of engineering products made from bamboo culms.     

Pectin and Xyloglucan Influence the Attachment of Salmonella enterica and Listeria monocytogenes to Bacterial Cellulose-Derived Plant Cell Wall Models

Minimally processed fresh produce has been implicated as a major source of foodborne microbial pathogens globally. These pathogens must attach to the produce in order to be transmitted. Cut surfaces of produce that expose cell walls are particularly vulnerable. Little is known about the roles that different structural components (cellulose, pectin, and xyloglucan) of plant cell walls play in the attachment of foodborne bacterial pathogens. Using bacterial cellulose-derived plant cell wall models, we showed that the presence of pectin alone or xyloglucan alone affected the attachment of three Salmonella enterica strains (Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028, and Salmonella enterica subsp. indica M4) and Listeria monocytogenes ATCC 7644. In addition, we showed that this effect was modulated in the presence of both polysaccharides. Assays using pairwise combinations of S. Typhimurium ATCC 14028 and L. monocytogenes ATCC 7644 showed that bacterial attachment to all plant cell wall models was dependent on the characteristics of the individual bacterial strains and was not directly proportional to the initial concentration of the bacterial inoculum. This work showed that bacterial attachment was not determined directly by the plant cell wall model or bacterial physicochemical properties. We suggest that attachment of the Salmonella strains may be influenced by the effects of these polysaccharides on physical and structural properties of the plant cell wall model. Our findings improve the understanding of how Salmonella enterica and Listeria monocytogenes attach to plant cell walls, which may facilitate the development of better ways to prevent the attachment of these pathogens to such surfaces.     

Non-pathogenic reoviruses of leafhoppers and planthoppers

Reoviruses of hoppers are reviewed with emphasis on their transmission, classification, and evolution. Plant reoviruses multiply in both plants and hopper vectors, whereas three non-pathogenic reoviruses are known; leafhopper A virus,Peregrinus maidisreovirus, andNilaparvata lugensreovirus (NLRV), that do not appear to cause disease in their insect hosts, and do not multiply in plants but share many properties with plant reoviruses. Genome analysis of NLRV would place it in the genusFijivirusin the family Reoviridae, and this assignment would be consistent with the biological and physicochemical properties of Fijiviruses, except for host range. The hypothesis that plant reoviruses originate as viruses exclusively of insects is studied.     

PcExl1 a Novel Acid Expansin-Like Protein from the Plant Pathogen Pectobacterium carotovorum,Binds Cell Walls Differently to BsEXLX1

Microbial expansins act on plant cell walls similarly to plant expansins, albeit their loosening activity levels are tenfold lesser compared to plant expansins. We report the characterization of an expansin-like gene from the plant pathogen Pectobacterium carotovorum, named exl1. PcExl1 is an acidic protein that binds cellulose (Avicel), and weakens filter paper. The acidic nature of PcExl1 confers different binding properties when compared to Bacillus subtilis BsEXLX1, which is a basic protein. PcExl1 binding to wheat cell wall increased when acidic components were depleted, reaching a similar level to the binding to Avicel, indicating that cellulose is the target of PcExl1.     

Community invasibility and invasion by non-native Fraxinus pennsylvanica trees in a degraded tropical forest

Whether invasion of introduced plant species may be aided by certain community properties is poorly understood for species-rich ecosystems, such as tropical montane forests. In Kenya, the non-native tree Fraxinus pennsylvanica has invaded degraded montane forests. We used generalized linear mixed models to examine the relative importance of different community properties to Fraxinus invasion after agricultural abandonment and in the secondary forest. Fraxinus invasion was positively related to plant community species diversity and the abundance of tree saplings, shrubs, ferns, and herbs in the abandoned fallows, but negatively related to the same community properties in the secondary forest. The number of Fraxinus recruits declined with declining propagule pressure in the fallows, but not in the secondary forest. Although adult and saplings of Fraxinus were positively related to community diversity in the fallows, Fraxinus appeared to decrease diversity in the secondary forest. These results show that the success of non-native species invasion and the effects of an invader on the resident community may depend both on properties and degree of disturbance of the community. Plant community diversity and evenness appeared to determine the invasion success by increasing invasibility of the abandoned fallows, but decreasing invasibility of the secondary forest. Our results from a tropical degraded forest emphasize the importance of including habitat characteristics when predicting both the potential of non-native plant invasion and effects of invasives on the particular community.