Number Of Plant Families Research Articles

Impacts of Parthenium hysterophorus L. on Plant Species Diversity in Ginir District, Southeastern Ethiopia

Invasive alien species are considered the second greatest global threat to biodiversity. This study is aimed at determining the impacts of Parthenium hysterophorus on herbaceous and woody plant species diversity in the Ginir district, southeast Ethiopia. Data on vegetation were collected from the three study sites’ four land use types, with each land use type having invaded and non-invaded land units. A systematic random sampling method was used for establishing sampling plots. To examine the impacts of the invasive on native plant diversity, a total of 160 plots (120 plots of 1 m2 on grazing lands, roadsides, and abandoned agricultural lands and 40 plots of 20 m2 for sampling herbaceous and tree (shrub) species, respectively) were established. The number of plots was equally distributed in both invaded and adjacent non-invaded areas. Plant species from each plot were recorded and identified. In each plot, all the individuals of P. hysterophorus were counted, the heights of the five tallest individuals were measured, and the mean height was calculated. The percentage cover of P. hysterophorus was visually estimated. The data were analyzed using both descriptive and inferential statistics. A total of 105 plant species (45 trees/shrubs and 60 herbaceous) belonging to 84 genera and 42 families were documented in the study area. The result showed a strong negative relationship between the density of P. hysterophorus and other plant species richness (r = −0.82, p = 0.013) and species abundance (r = −0.917, p = 0.001) per study site of the invaded community. Species richness in the non-invaded site was higher (105 species) than in the invaded area (63 species), demonstrating the negative impact of P. hysterophorus on local biodiversity. Furthermore, the number of plant families was 42 in the non-invaded area, in contrast to only 32 in the invaded areas, a 23.8% decline. Of the plant communities, similarity indices between non-invaded and invaded sites among different land use types were >50%. It was concluded that P. hysterophorus was one of the most dominant invasive alien species in the study area that reduced the species diversity of various plant species. Putting in place a strategy and effective planning for the control and management of this invasive alien species is strongly recommended.

Size‐selective exclusion of mammals and invertebrates differently affects grassland plant communities depending on vegetation type

Abstract Human‐caused loss of vertebrate and invertebrate animals, defaunation, is increasing, and potentially affects plant community structure of diverse grassland ecosystems world‐wide. We experimentally simulated defaunation using size‐selective fences to progressively exclude large‐, medium‐ and small‐sized mammals, and invertebrates from two subalpine vegetation types in the Swiss National Park (SNP): intensively grazed short‐grass and moderately grazed tall‐grass vegetation. We assessed plant community properties yearly from 2009 to 2013, and examined treatment effects on plant community structure in the two grassland types. In the short‐grass vegetation, the exclusion of large mammals increased total plant biomass, while the exclusion of large and medium‐sized mammals increased total, grass and forb biomass compared to when all animals had access. These increases became stronger when invertebrates were also excluded. The exclusion of all mammals and invertebrates increased biomass of grasses by 205%, forbs by 100% and total plant biomass by 118% compared to when all animals had access, hence enhancing relative biomass of grasses from 43.6% to 60%, changing plant species composition and lowering richness of forbs by 16%, the number of plant families by 13% and family‐level Shannon diversity by 23%. In contrast to these significant community‐level responses found in the short‐grass vegetation, there was no evidence that the size‐selective exclusion of animals altered the plant community structure of the tall‐grass vegetation. The contrasting results were due to the difference in plant community composition prior to our experiment, which were related to differences in quantity and quality of forage and in grazing intensities of herbivores between the two grassland types. Synthesis. Our results showed that different‐sized animals, in particular large mammals and invertebrates, contributed to maintain the plant community structure in the short‐grass vegetation, highlighting the importance of multiple, functionally different animal groups for ecosystem functioning and stability. In contrast to the short‐grass vegetation, we could not detect such a top‐down control by animals in the tall‐grass vegetation. Our results suggest that potential defaunation effects on grassland plant community structure depend on the degree of grazing pressure release and grassland vegetation type.

The association between bushclumps of Calcrete Bontveld and the adjacent Valley Thicket

Calcrete Bontveld is a mosaic vegetation that occurs on flat-topped calcareous ridges adjacent to solid Valley Thicket in the Albany Thicket biome of South Africa. It consists of thicket clumps (bushclumps) scattered in a grassy dwarf shrubland matrix. While the bushclumps of Calcrete Bontveld represent the thicket component in the mosaic the extent and nature of similarity between the bushclumps and adjacent solid Valley Thicket remains unresolved. This study considers the relationship between the thicket communities of these two spatially separate but proximal vegetation types. As expected, bushclumps share a substantive compositional similarity and structure with the nearby solid Valley Thicket but minimally so with the surrounding grassy dwarf shrubland matrix. The latter is made up of elements of other biomes with only a few thicket taxa. The Bushclump composition differs from the adjacent solid Valley Thicket in that it is less succulent and less diverse in the number of plant families. A total of 22 Thicket species were absent from the bushclumps – notably a few iconic ones: trees Portulacaria afra, shrubs Cotyledon velutina, Euphorbia mammilaris and Kalanchoe rotundifolia, as well as the geophyte, Gasteria bicolor. By contrast, only 8 taxa were found only in the bushclumps, but not in the local form of solid Valley Thicket (e.g. Ptaeroxylon obliquum and Scolopia zeyheri). Several of these have a Cape Thicket affinity – e.g. trees Colpoon compressum and Pterocelastrus tricuspidatus and the shrub Diospyros dichrophylla. The absence of many adjacent thicket species from the bushclumps provides evidence for exchange exclusion of propagules of some Valley Thicket taxa from the bushclumps of Calcrete Bontveld. However, the unique bushclumps are a suitable habitat for establishment of the more distant Cape-affinity taxa.

Geographical Patterns in the Architecture of Neotropical Flower-visitor Networks of Hummingbirds and Insects.

Geographical variations in environmental factors can affect species diversity and consequently influence the structure of interspecific ecological interactions. Relationships between flowering plants and animal flower visitors are among the most important ecological interactions and can structure and maintain ecological diversity in different environments. Additionally, many animal and plant species participate in these interactions, which shape the specific characteristics of these communities, in terms of both the responses of the interacting species involved and environmental differences. Therefore, in the present study we investigated geographical and environmental effects on the architecture of Neotropical flower-visitor networks of vertebrates and invertebrates. To this end, we used data regarding interaction networks available in the literature and constructed binary interaction networks of plants and plant-visitors (hummingbirds and insects) and tested the effects of altitude, latitude, vegetation type and number of plant families on the structure of these networks. In total, we analyzed 55 networks of flower-visitor interactions with 746 species of flower-visiting animals and 1,185 species of plants, totaling 5,463 distinct plant-animal interactions. In general, the architecture of flower-visitor networks varied along latitudinal and altitudinal gradients, with more pronounced effects for flower-insect networks in which latitude influenced network size, modularity, and nestedness, and altitude influenced network size and connectance. Flower-hummingbird networks in open vegetation (grassland) were more modular than networks in other environments. The number of plant families positively influenced the size of insect and hummingbird networks, and positively affected connectance and nestedness and negatively affected modularity in the flower-insect networks. So, the patterns we found indicate that plant-visitor interactions in flower-insect and flower-hummingbird networks are differently affected by geographical and plant-related factors, possibly due to the differences in taxonomic and functional groups involved in these interactions.

PlantFAdb: a resource for exploring hundreds of plant fatty acid structures synthesized by thousands of plants and their phylogenetic relationships.

Over 450 structurally distinct fatty acids are synthesized by plants. We have developed PlantFAdb.org, an internet-based database that allows users to search and display fatty acid composition data for over 9000 plants. PlantFAdb includes more than 17000 data tables from >3000 publications and hundreds of unpublished analyses. This unique feature allows users to easily explore chemotaxonomic relationships between fatty acid structures and plant species by displaying these relationships on dynamic phylogenetic trees. Users can navigate between order, family, genus and species by clicking on nodes in the tree. The weight percentage of a selected fatty acid is indicated on phylogenetic trees and clicking in the graph leads to underlying data tables and publications. The display of chemotaxonomy allows users to quickly explore the diversity of plant species that produce each fatty acid and that can provide insights into the evolution of biosynthetic pathways. Fatty acid compositions and other parameters from each plant species have also been compiled from multiple publications on a single page in graphical form. Links provide simple and intuitive navigation between fatty acid structures, plant species, data tables and the publications that underlie the datasets. In addition to providing an introduction to this resource, this report illustrates examples of insights that can be derived from PlantFAdb. Based on the number of plant families and orders that have not yet been surveyed we estimate that a large number of novel fatty acid structures are still to be discovered in plants.

Deciphering the influence of column chemistry and mass spectrometry settings for the analyses of geometrical isomers of L-chicoric acid.

Resolving the chemo-diversity of plant extract samples is an essential step for in-depth analyses of natural products which often exhibit promising biological activities. One of the challenges in this endeavor has been the confident differentiation of geometrical isomers. In this study, we investigated these aspects in chromatography (column chemistry and mobile phase composition) and mass spectrometry settings with regards to better differentiation of geometrical isomers. A standard of a hydroxycinnamic acid (HCA) derivative, L-chicoric acid (L-CA) - a di-acylated caffeoyltartaric acid ester found in a number of plant families - was used. Geometrical isomers of L-CA were formed by exposing the compound to ultraviolet (UV) radiation, to mimic the natural environment. The high performance liquid chromatography photo-diode array (HPLC-PDA) and ultra-high performance liquid chromatography mass spectrometry (UHPLC-MS) platforms were used to analyze the trans and cis geometrical isomers of L-CA. The HPLC-PDA results confirmed the generation of two cis geometrical isomers following UV exposure of the authentic trans-L-CA standard. Furthermore, the HPLC-PDA analyses demonstrated that the changes in both column chemistry (reverse-phase: C18, biphenyl, phenyl-hexyl and pentafluorophenyl propyl) and mobile phase composition (aqueous acetonitrile and aqueous methanol) affect the chromatographic elution profiles of the L-CA isomers. The MS results, on the other hand, revealed undisputed fragmentation differences between the geometrical isomers of L-CA. Thus, this study demonstrates that the identification of the L-CA isomers can be achieved more efficiently and confidently with good chromatography coupled to well-optimized mass spectrometry conditions, a requirement which has been proven impossible with other types of HCA derivatives. Moreover, differences in the binding modes of L-CA geometrical isomers to the HIV type 1 integrase enzyme were observed, suggesting a synergistic anti-HIV-1 activity of these isomers.

Morphological and DNA Barcoding Evidence for Invasive Pest Thrips, Thrips parvispinus (Thripidae: Thysanoptera), Newly Recorded From India.

South East Asia pest thrips species, Thrips parvispinus (Karny), is a serious pest on a number of agricultural and horticultural crops in a number of plant families. Based on an integrated approach of morphology and DNA barcoding, invasion of this serious pest is reported first time from India on papaya plantations. Molecular data have corroborated with the morphological identification. Haplotyping data suggested that the Indonesia may be a probable source of invasion of this pest to India.

High performance liquid chromatography-diode array detector (HPLC-DAD) detection of trans-resveratrol: Evolution during ripening in grape berry skins

Trans-resveratrol (3, 5, 4' – trihydroxy-trans-stilbene) is a stilbene naturally present in a number of plant families. Berry skins of grape (Vitis vinifera L.), Alicante, Black Malvasia, Nerello and Prunesta cultivars were analyzed at weekly intervals for trans-resveratrol production at five ripening stages during the last five weeks of maturation, from August 26th to September 23th. Analysis was carried out using the high performance liquid chromatography-diode array detector (HPLC-DAD) technique after fractioning of trans-resveratrol through a 500 mg C18 column (Solid Phase Isolation – SPI technique). A continuous decrease in trans-resveratrol content in all cultivars was observed during ripening. Alicante had the highest trans-resveratrol content, showing a decrease of 46% from the first to last sampling, while Black Malvasia produced the lowest amount of trans-resveratrol, 4 to 5 times less than Alicante at each sampling date. Key words: Antioxidants, grape, phenols, stilbenes, trans-resveratrol, high performance liquid chromatograph (HPLC).

Synthesis of 7,8-epi-Valtrate from (+)-Genipin

E-mail: sjlee@kwandong.ac.krReceived August 30, 2012, Accepted September 11, 2012Key Words : Valepotriate, Valtrate, Diene-type valepotriate, Genipin, Organic synthesis Valepotriates are natural products of a large number ofplant families. They belong to the iridoids, which are cyclo-pentan-c-pyran monoterpenoids, often in the form of glyco-sides

A set of regioselective O-methyltransferases gives rise to the complex pattern of methoxylated flavones in sweet basil.

Polymethoxylated flavonoids occur in a number of plant families, including the Lamiaceae. To date, the metabolic pathways giving rise to the diversity of these compounds have not been studied. Analysis of our expressed sequence tag database for four sweet basil (Ocimum basilicum) lines afforded identification of candidate flavonoid O-methyltransferase genes. Recombinant proteins displayed distinct substrate preferences and product specificities that can account for all detected 7-/6-/4'-methylated, 8-unsubstituted flavones. Their biochemical specialization revealed only certain metabolic routes to be highly favorable and therefore likely in vivo. Flavonoid O-methyltransferases catalyzing 4'- and 6-O-methylations shared high identity (approximately 90%), indicating that subtle sequence changes led to functional differentiation. Structure homology modeling suggested the involvement of several amino acid residues in defining the proteins' stringent regioselectivities. The roles of these individual residues were confirmed by site-directed mutagenesis, revealing two discrete mechanisms as a basis for the switch between 6- and 4'-O-methylation of two different substrates. These findings delineate major pathways in a large segment of the flavone metabolic network and provide a foundation for its further elucidation.

An Ultrastructural Approach to the Question of Integrity of Senescent Peltate Hairs in Origanum dictamnus Leaves

In a number of plant families, various species bear on their leaves numerous peltate hairs secreting lipophilic substances (essential oils, resins, etc.). Peltate hairs are usually composed of a foot (unicellular), a stalk (unicellular), and a head (multicellular). In the head, biosynthesis and secretion of the lipophilic material take place. Head cells, when active in secretion, possess thickly arranged ribosomes and many mitochondria and plastids, whereas other organelles (dictyosomes, ER-elements, etc.) occur in small numbers. At the stage of senescence, head cells appear lysed (including dark “foamy” protoplasm, cell plasmolysis, folding of the cell walls, disorganization of organelles and membranes). Available reports on senescent peltate hairs indicate that the peltate hairs do not retain their integrity. Thus, when the head degenerates, it separates from the stalk and falls down, or the head along with the stalk degenerates and drops or the entire hair shrinks and falls. In Origanum dictamnus, during peltate hair senescence, the head and the stalk degenerate, whereas the foot remains living. However, no separation (and subsequent falling) of the head or the head and stalk has been observed.

Strigolactones seem not to be involved in the nonsusceptibilty of arbuscular mycorrhizal (AM) nonhost plants to AM fungi

Although most land plants are hosts for arbuscular mycorrhizal fungi (AMF), a small number of plant families are arbuscular mycorrhizal (AM) nonhosts. There are indications that strigolactone levels in root exudates of AM nonhost plants are lower than in AM host plants, and it has been shown that in the strigolactone-deficient rms1 mutant (ccd8) of the AM host plant pea, the AMF colonization of roots is highly reduced. Application of the synthetic strigolactone analogue GR24 to this strigolactones-deficient mutant restored AMF colonization of roots. Our objective was to determine whether the application of GR24 to AM nonhost plants can affect their susceptibility to AMF. To test whether GR24 affects AMF colonization in our experimental system, we added GR24 to the strigolactone-deficient pea ccd8 mutant. Application of GR24 increased AMF colonization in the pea mutant to a similar level as in the pea wild type with normal strigolactone levels, showing clearly that in our experimental setup, application of the GR24 positively affects AMF colonization in strigolactone-deficient plants. Observation of cleared roots after application of GR24 to four AM nonhost plant species inoculated with the AMF Glomus intraradices showed that colonization did not occur.

Protocols for in vitro cultures and secondary metabolite analysis of aromatic and medicinal plants

This book edited by S. Mohan Jain and Praveen K. Saxena covers a range of topics vital for the continued production of this essential but sometimes forgotten group of plants. Plants have always been an important part of traditional medicine; however, recently there has been increasing interest in and acceptance of using plant-based medicines. This has led to indiscriminate harvesting of wild species resulting in many species becoming endangered. This is a recurring theme in the book; micropropagation of endangered species, germplasm conservation, or using cell culture as an alternative to field cultivation for the aromatic and medicinal species. The book consists of 31 chapters, which are divided into five sections titled as follows: ‘Micropropagation and chemical analysis’, ‘Transgenic approaches’, ‘Molecular markers and microsatellites’, ‘Biotransformation, bioreactors and metabolomics’, and ‘Altered gravity and biotechnology’. The first section gives step-by-step procedures for propagating a number of medicinal plants that are endangered or hard to germinate. These chapters also cover the important bioactives found in the plants, the uses of these compounds, and protocols for biochemical analysis of the tissue-culture-derived plants. All chapters provide excellent notes on in vitro culture of the plants, the materials required, the media formulations, and the suppliers of the equipment or chemicals. The notes are in depth, with one example of field instructions reminding readers to ‘bring a raincoat’ and ‘understand risks from wild animals, spiders, insects or snakes’. The second section deals with transformation of medicinal and aromatic plants for the production of bioactive compounds and for basic research. Transformation via hairy root cultures, particle bombardment, and Agrobacterium tumefaciens-mediated transformation methodologies are provided as well as procedures for analysis of the transformants. The third section of the book deals with molecular markers and microsatellites. These two chapters deal with identification of medicinal plants by microarrays with MLPA (multiplexed ligase-dependent probe amplication) and microsatellites. Identification of the correct plant species is extremely important for medicinal plants, as wrong classification of a plant can have deadly results. The fourth section of the book focuses on biotransformation, bioreactors and metabolomics. A number of medicinal plants are very hard to grow or are slow growing, and therefore field cultivation is not the most desired system for producing the medicinally important bioactives. Developing cell cultures from these medicinal and aromatic plants and extracting the pharmaceutical compound is an alternative method to field production. Bioreactors allow for continuous extraction of the important bioactives from plant cell suspensions. This section also gives information on metabolomic analysis of cell cultures, a newer approach to survey all the metabolites in a plant. The last section looks at biotechnology for anti-cancer compounds and plant secondary metabolism under altered plant environments (altered gravity). These chapters are reviews and do not contain protocols but discuss results. The book takes us from micropropagating endangered plants for return to field conditions all the way to growing plants for long-term colonization of space. The methodology does not stop at the tissue culture stage, but goes on to include biochemical analysis of the plants for the important bioactive compounds. One of the benefits of this book is to have both aspects within one volume. The book covers a number of plant families (annual flowering plants, woody species, berries, tubers, water plants, orchids and bryophytes) that are grown in China, India, North America and Europe. These plants have bioactives that are beneficial for treatment of a range of diseases and ailments. The chapters are easy to read and the protocols are easy to follow. All the necessary information is within the chapter. Most of the chapters have pictures depicting the equipment, tissue cultures at different stages, or in vitro derived plants. Unfortunately, the pictures are all in black and white. I feel that it would have been beneficial to have some of the pictures in colour, especially the ones illustrating callus or suspension cultures. In conclusion, I would recommend this book to researchers and students working in the area of plant tissue culture and biochemical analysis. This book would also be beneficial as a text book or laboratory manual in plant tissue culture courses.

Nectar‐feeding bird and bat niches in two worlds: pantropical comparisons of vertebrate pollination systems

AbstractAim We review several aspects of the structure of regional and local assemblages of nectar‐feeding birds and bats and their relationships with food plants to determine the extent to which evolutionary convergence has or has not occurred in the New and Old World tropics.Location Our review is pantropical in extent and also includes the subtropics of South Africa and eastern Australia. Within the tropics, it deals mostly with lowland forest habitats.Methods An extensive literature review was conducted to compile data bases on the regional and local species richness of nectar‐feeding birds and bats, pollinator sizes, morphology, and diets. Coefficients of variation (CVs) were used to quantify the morphospace occupied by the various families of pollinators. The extent to which plants have become evolutionarily specialized for vertebrate pollination was explored using several criteria: number and diversity of growth forms of plant families providing food for all the considered pollinator families; the most common flower morphologies visited by all the considered pollinator families; and the number of plant families that contain genera with both bird‐ and bat‐specialized species.Results Vertebrate pollinator assemblages in the New World tropics differ from those in the Old World in terms of their greater species richness, the greater morphological diversity of their most specialized taxa, and the greater degree of taxonomic and ecological diversity and morphological specialization of their food plants. Within the Old World tropics, Africa contains more specialized nectar‐feeding birds than Asia and Australasia; Old World nectar‐feeding bats are everywhere less specialized than their New World counterparts.Main conclusions We propose that two factors – phylogenetic history and spatio‐temporal predictability (STP) of flower resources – largely account for hemispheric and regional differences in the structure of vertebrate pollinator assemblages. Greater resource diversity and resource STP in the New World have favoured the radiation of small, hovering nectar‐feeding birds and bats into a variety of relatively specialized feeding niches. In contrast, reduced resource diversity and STP in aseasonal parts of Asia as well as in Australasia have favoured the evolution of larger, non‐hovering birds and bats with relatively generalized feeding niches. Tropical Africa more closely resembles the Neotropics than Southeast Asia and Australasia in terms of resource STP and in the niche structure of its nectar‐feeding birds but not its flower‐visiting bats.

Need for protective measures to combat potential outbreaks of Homalodisca coagulata and Pierce's Disease in European viticulture

Pierce's Disease (PD) is a lethal disease of grapevines (Vitis vinifera) caused by a strain of the bacterium Xylella fastidiosa. At the end of the 1990s, PD spread rapidly in California after accidental introduction of the non-native vector glassy-winged sharpshooter (Homalodisca coagulata). The new vector, which prefers citrus as a host for reproduction and overwintering, transmits the bacteria very efficiently to a large variety of plants and is a threat not only to the state's production of grapes, but also to large-scale cultivation of, e.g., almonds and peaches. In order to stop the spread of the new vector and protect the wine industry from PD, quarantine measures have been put into effect and several research projects concerning pest management strategies have been initiated. From a European perspective, interesting results have been achieved by the use of a climate model. This model predicts that cold stress accumulation would exclude PD within wine-producing regions of Europe. However, some reports suggest the existence of cold-tolerant X. fastidiosa PD-causing strains, which could exhibit an invasion potential. Because of global trade and the fact that both the bacterium and the vector are associated with a large number of plant families, other temperate areas such as those in parts of Europe where grape and citrus production dominate are now under threat. The European and Mediterranean Plant Protection Organization (EPPO) has decided to consider H. coagulata a serious threat and is currently asking member countries to pay particular attention to this organism. From experience gained in California, H. coagulata needs to be combated using a palette of measures. Suggested initiatives to prevent introduction to Europe could involve quarantine and/or phytosanitary regulations and consideration of tourist traffic regulation between, for instance, Europe and North America and between Europe and Polynesia. However, current phytosanitary regulatory policies in California indicate that such regulations are not sufficient to prevent outbreaks. Preparation of action plans to be followed in the event of an outbreak should therefore carefully take note of the experience gained so far in deciding which eradication measures should be implemented and at which level of infestation. In the following, the spread of PD is presented and discussed with respect to previous experiences. Knowledge generated within California, such as such use of clay particle sprays and physical barriers and biological control with egg parasitoids, is suggested to be an important tool for European viticulturalists to combat potential outbreaks.

ANTIVIRAL EFFECTS OF SAIKOSAPONINS ON HUMAN CORONAVIRUS 229E IN VITRO

SUMMARY 1Saikosaponins represent a group of oleanane derivatives, usually as glucosides, that are found in a number of plant families. Saikosaponins isolated from medicinal plants such as Bupleurum spp., Heteromorpha spp. and Scrophularia scorodonia have been reported to possess various biological activities, specifically antihepatitis, antinephritis, antihepatoma, anti‐inflammation, immunomodulation and antibacterial effects.2The aim of the present study was to examine the anticoronaviral activity of saikosaponins (A, B2, C and D) and their mode of action. Using the 2,3‐bis[2‐methoxy‐4‐nitro‐5‐sulfophenyl]‐5‐[(phenylamino) carbonyl‐2H‐tetrazolium hydroxide] (XTT) assay, results showed that all saikosaponins tested demonstrated antiviral activity at concentrations of 0.25–25 µmol/L, with the strongest activity being noted for saikosaponin B2 (IC50 = 1.7 ± 0.1 µmol/L). Interestingly, both saikosaponins A (50% cellular cytotoxicity (CC50) concentration = 228.1 ± 3.8 µmol/L; selectivity index (SI) = 26.6) and B2 (CC50 = 383.3 ± 0.2 µmol/L; SI = 221.9) exhibited no cytotoxic effects on target cells at concentrations that achieved antiviral activity. In the time‐of‐addition studies, saikosaponin B2, at 6 µmol/L, significantly inhibited human coronavirus 229E infection following its addition at various time pre‐infection (−4 to −1 h), coinfection (0 h) and post‐infection (1–4 h). Furthermore, saikosaponin B2 also showed an inhibitory effect on viral attachment and penetration.3The present results indicate that saikosaponin B2 has potent anticoronaviral activity and that its mode of action possibly involves interference in the early stage of viral replication, such as absorption and penetration of the virus.

Development and characterization of near‐isogenic lines of sorghum segregating for glycinebetaine accumulation

Glycinebetaine (GB) is a compatible solute synthesized by species in a number of plant families, including some grasses such as sorghum (Sorghum bicolor L. Moench). A recombinant‐inbred (RI) population was developed from a cross between GB‐deficient (IS2319) and GB‐accumulating (P932296) sorghum genotypes. The proportions of GB‐accumulating lines in both the F5 and F7:8 generations of this RI population were higher than expected, possibly due to some beneficial effect of GB accumulation on plant growth, survival or seed set. GB levels varied widely in lines of the RI population that were grown under controlled conditions, suggesting genetic control not only for the presence or absence of GB, but also for the level of GB. This hypothesis was tested by analysing individual plants from lines identified as accumulating low, medium or high concentrations of GB based on the F5 and F7:8 screens. The level of GB was conserved within lines, supporting the hypothesis of genetic control of relative GB levels within accumulating lines. Two pairs of near‐isogenic lines (NILs) with contrasting GB levels within pairs were developed from the RI population. The stable inheritance of the GB phenotype and isogenicity of these NILs were confirmed with progeny tests and molecular marker analysis, respectively. Labelling studies demonstrated that the deficiency in GB accumulation was at the choline oxidation step.

Agroinfiltration is a versatile tool that facilitates comparative analyses of Avr9/Cf-9-induced and Avr4/Cf-4-induced necrosis.

The avirulence genes Avr9 and Avr4 from the fungal tomato pathogen Cladosporium fulvum encode extracellular proteins that elicit a hypersensitive response when injected into leaves of tomato plants carrying the matching resistance genes, Cf-9 and Cf-4, respectively. We successfully expressed both Avr9 and Avr4 genes in tobacco with the Agrobacterium tumefaciens transient transformation assay (agroinfiltration). In addition, we expressed the matching resistance genes, Cf-9 and Cf-4, through agroinfiltration. By combining transient Cf gene expression with either transgenic plants expressing one of the gene partners, Potato virus X (PVX)-mediated Avr gene expression, or elicitor injections, we demonstrated that agroinfiltration is a reliable and versatile tool to study Avr/Cf-mediated recognition. Significantly, agroinfiltration can be used to quantify and compare Avr/Cf-induced responses. Comparison of different Avr/Cf-interactions within one tobacco leaf showed that Avr9/Cf-9-induced necrosis developed slower than necrosis induced by Avr4/Cf-4. Quantitative analysis demonstrated that this temporal difference was due to a difference in Avr gene activities. Transient expression of matching Avr/Cf gene pairs in a number of plant families indicated that the signal transduction pathway required for Avr/Cf-induced responses is conserved within solanaceous species. Most non-solanaceous species did not develop specific Avr/Cf-induced responses. However, co-expression of the Avr4/Cf-4 gene pair in lettuce resulted in necrosis, providing the first proof that a resistance (R) gene can function in a different plant family.

Diet breadth and host plant diversity of tropical‐ vs. temperate‐zone herbivores: South‐East Asian and West Palaearctic butterflies as a case study

1. Data on host plant associations of butterflies (Papilionoidea, excluding Hesperiidae) from two biogeographical regions were used to investigate (1) whether tropical herbivores are more narrowly specialized with regard to host plant choice than those of northern temperate zones, and (2) whether tropical butterflies show a greater diversity of host plant affiliations.2. There was no evidence for a more restricted diet breadth of tropical butterflies, with diet breadth being measured as number of host plant families used per species. In the families Papilionidae, Pieridae, and Nymphalidae, host plant ranges of West Palaearctic and South‐East Asian species are similar, whereas in one speciose group within the Lycaenidae, the Polyommatini, tropical species are significantly more polyphagous.3. Diet breadth also differs among higher butterfly taxa. While Papilionidae, Pieridae, the nymphalid subfamilies Satyrinae, Morphinae, Libytheinae and Apaturinae, as well as the temperate‐zone Polyommatini in the Lycaenidae are composed predominantly of host specialists, the degree of polyphagy is higher among the remaining nymphalid subfamilies and in many lycaenids. These results challenge strongly the view that tropical herbivores are generally more specialized in this regard than herbivores of higher latitudes. Rather, chemical constraints and phylogenetic conservatism shape host plant associations in many taxa in such a way that differences between temperate and tropical representatives are slight.4. Host plant diversity, measured as the number of plant families used per butterfly family and by application of the log‐series model, is much higher in South‐East Asian Nymphalidae and Lycaenidae (the two largest families) than in their Western Palaearctic relatives. No such differences are observed in the Papilionidae and Pieridae (the two smaller families). Besides effects of sample size, the strong association of papilionid and pierid butterflies with plants characterized by a small set of classes of secondary plant compounds might generally restrict their capability to utilize a broader taxonomic range of host plants.5. The results indicate that high floral diversity can be reflected by higher diversity of host plant affiliations of herbivores, but taxonomic idiosyncrasies render it difficult to draw generalized conclusions.

Mutations in the PERIANTHIA gene of Arabidopsis specifically alter floral organ number and initiation pattern.

An open question in developmental biology is how groups of dividing cells can generate specific numbers of segments or organs. We describe the phenotypic effects of mutations in PERIANTHIA, a gene specifically required for floral organ patterning in Arabidopsis thaliana. Most wild-type Arabidopsis flowers have 4 sepals, 4 petals, 6 stamens, and 2 carpels. Flowers of perianthia mutant plants most commonly show a pentamerous pattern of 5 sepals, 5 petals 5 stamens, and 2 carpels. This pattern is characteristic of flowers in a number of plant families, but not in the family Brassicaceae, which includes Arabidopsis. Unlike previously described mutations affecting floral organ number, perianthia does not appear to affect apical or floral meristem sizes, nor is any other aspect of vegetative or floral development severely affected. Floral organs in perianthia arise in a regular, stereotypical pattern similar to that in distantly related species with pentamerous flowers. Genetic analysis shows that PERIANTHIA acts downstream of the floral meristem identity genes and independently of the floral meristem size and floral organ identity genes in establishing floral organ initiation patterns. Thus PERIANTHIA acts in a previously unidentified process required for organ patterning in Arabidopsis flowers.