A combined physical and physiological dormancy controls seasonal seedling emergence of Geranium robertianum

Temperate forest herbs with seeds exhibiting both a physical and a physiological dormancy mechanism are rare, and knowledge on the factors regulating germination of these species is fragmentary. The biennial Geranium robertianum L. grows mainly in temperate woodlands, but can also be found in exposed habitats. Seedlings of G. robertianum are known to emerge from spring until autumn, but little is known about the environmental factors regulating germination. In this study, phenology of seedling emergence and of physical dormancy loss was examined for seeds buried at shaded or sunny exposed locations. The role of temperature in regulating dormancy and germination was analysed by incubating seeds in temperature sequences simulating temperatures that seeds experience in nature. The results indicate that most seeds of G. robertianum buried in sunny conditions germinate immediately after physical dormancy loss in summer. Seeds buried in shaded conditions also lose physical dormancy mainly during summer, but remain physiologically dormant and do not germinate until late winter or early spring. Besides physical dormancy, seeds of G. robertianum also initially have a high level of physiological dormancy, which is reduced during dry storage. Physiological dormancy is reduced through chilling in winter, thus enabling the seeds to germinate at low temperatures. We conclude that a complex combination of physical and physiological dormancy ensures that G. robertianum seeds germinate in summer at exposed sites and in early spring at shaded sites.     

Morphology, ontogeny and histochemistry of secretory trichomes of Geranium robertianum (Geraniaceae)

Geranium robertianum bears three types of glandular uniseriate trichomes which originate from a single protodermal cell and develop through periclinal divisions. Type I trichomes are procumbent and have an oval apical cell, two stalk cells and a basal cell. Type II trichomes are erect and have a pear shaped apical cell, two stalk cells and a basal cell. Type III trichomes are much longer than the other two types and have an elongated apical cell, five long stalk cells and a basal cell. Type I and type II trichomes are common on leaves while III trichomes are more abundant on flower structures.
Type I and type II trichomes secrete terpenoids and phenols. Type III trichomes are characterized by the accumulation of anthocyanins in the apical cell and secrete flavonoids.     

"MitoTea": Geranium robertianum L. decoctions decrease blood glucose levels and improve liver mitochondrial oxidative phosphorylation in diabetic Goto-Kakizaki rats

Several chemical compounds found in plant products have proven to possess beneficial properties, being currently pointed out due to their pharmacological potential in type 2 diabetes mellitus complications. In this context, we studied the effect of Geranium robertianum L. (herb Robert) leaf decoctions in Goto-Kakizaki (GK) rats, a model of type 2 diabetes. Our results showed that oral administration of G. robertianum leaf decoctions over a period of four weeks lowered the plasma glucose levels in diabetic rats. Furthermore, the treatment with G. robertianum extracts improved liver mitochondrial respiratory parameters (state 3, state 4 and FCCP-stimulated respiration) and increased oxidative phosphorylation efficiency.     

Volatiles of Geranium purpureum Vill. and Geranium phaeum L.: Chemotaxonomy of Balkan Geranium and Erodium Species (Geraniaceae)

The essential oils obtained by hydrodistillation of Geranium purpureum and G. phaeum were characterized by GC‐FID and GC/MS analyses (the former for the first time in general). In total, 154 constituents were identified, accounting for 89.0–95.8% of the detected GC peak areas. The investigated essential oils consisted mainly of fatty acids and fatty‐acid‐derived compounds (45.4–81.3%), with hexadecanoic acid and (E)‐phytol as the major components. The chemotaxonomic significance of the variations in the essential‐oil composition/production of the presently and previously investigated Geranium and highly related Erodium taxa from Serbia and Macedonia was assessed by multivariate statistical analyses. The main conclusions drawn from the high chemical similarity of the two genera, visible from the obtained dendrograms and biplots, confirm the close phylogenetic relationship between the investigated Geranium and Erodium taxa, i.e., that there is no great intergeneric oil‐composition variability. Changes in the composition and production of essential oils of the herein investigated taxa and 60 other randomly chosen species belonging to different plant genera were also statistically analyzed. The results put forward pro arguments for the oil‐yield–oil‐composition correlation hypothesis.     

Synorganisation without organ fusion in the flowers of Geranium robertianum (Geraniaceae) and its not so trivial obdiplostemony

Background and Aims

Synorganisation of floral organs, an important means in angiosperm flower evolution, is mostly realized by congenital or post-genital organ fusion. Intimate synorganisation of many floral organs without fusion, as present in Geranium robertianum, is poorly known and needs to be studied. Obdiplostemony, the seemingly reversed position of two stamen whorls, widely distributed in core eudicots, has been the subject of much attention, but there is confusion in the literature. Obdiplostemony occurs in Geranium and whether and how it is involved in this synorganisation is explored here.

Methods

Floral development and architecture were studied with light microscopy based on microtome section series and with scanning electron microscopy.

Key Results

Intimate synorganisation of floral organs is effected by the formation of five separate nectar canals for the proboscis of pollinators. Each nectar canal is formed by six adjacent organs from four organ whorls. In addition, the sepals are hooked together by the formation of longitudinal ribs and grooves, and provide a firm scaffold for the canals. Obdiplostemony provides a guide rail within each canal formed by the flanks of the antepetalous stamen filaments.

Conclusions

Intimate synorganisation in flowers can be realized without any fusion, and obdiplostemony may play a role in this synorganisation.     

Effects of belowground grazing by collembola on growth,mycorrhizal infection,and P uptake of Geranium robertianum

We hypothesized that the grazing of vesicular-arbuscular mycorrhizal (VAM) hyphae by soil animals could be responsible for the lack of a direct relationship between mycorrhizal infection intensity and nutrient uptake under field conditions. To test this hypothesis, we determined the effect of a range of densities of the collembola, Folsomia candida, on growth, VAM infection, and P uptake in Geranium robertianum, a common forest herb, under greenhouse conditions. Total and aboveground growth were greater at low collembola density than either at higher collembola density or without collembola. These differences were greater when the plants were grown in a high organic content soil mix than when grown in sand. Root mass was not affected by collembola density. In the soil mix, root length decreased with increasing collembola density, but not in the sand. The percent of root length infected with VAM was lower at any collembola density than when collembola were absent. Total infected root length decreased linearly with increasing collembola density. Few significant differences in P uptake or tissue concentration were found. Thus, plant growth (but not P uptake) may be stimulated at low collembola density and inhibited at high. We discuss mechanisms which may be responsible for this non-linear response, and the implications of the pattern of response to studies of plant competition, nutrient turnover, and revegetation.     

草原老鹳草的组织培养和快速繁殖

1植物名称草原老鹳草（Geranium pratense L．）。2材料类别种子、根状茎、叶片。3培养条件种子萌发培养基：（1）MS;芽诱导与增殖培养基：（2）MS＋6-BA0．2mg·L-1（单位下同）＋NAA0．02,（3）MS＋6-BA0．5＋NAA0．05,（4）MS＋6-BA1．0＋NAA0．2,（5）MS＋6-BA2．0＋NAA0．2;生根培养基：（6）1／2MS,（7）112MS＋2g．L-1活性炭。培养基中附加0．6％琼脂和3％蔗糖,pH5．8。培养室温度为（24±2）℃,光照强度为50-60lamol·m-2．s-1,光照时间为12h．d-1（吕晋慧等2005）。     

野老鹳草DNA的提取方法及RAPD分析

目的：以野老鹳草（Geranium carolinianum L．）的茎、叶为材料,研究野老鹳草DNA的提取方法及RAPD的分析。方法：采用CATB法、高盐低pH法和SDS法分别提取野老鹳草的基因纽DNA,并对3种方法进行了一些改进。通过RAPD分析所提取的DNA,比较所用的提取方法。结果：比较DNA产量、质量等,确定了高盐低pH法较佳。结论：干燥的材料和新鲜的材料均可提取得到DNA,高盐低pH法提取的效果优于CTAB和SDS法。     

Callus and suspension cultures fromGeranium robertianum L (Geraniaceae)

Summary Frieble calli, obtained from petioles ofGeranium roberlianum were used for the production of cell suspension cultures in liquid MS modified medium supplemented with BAP and NAA. Casamino acids were shown to be necessary for suspension cultures establishment With a 15.9×10⁴ cell. ml^–1 concentration a td=38.2h was achieved.     

Further Antibacterial Geranium macrorrhizum L. Metabolites and Synthesis of Epoxygermacrones

4,5‐ and 1,10‐Epoxygermacrones were isolated from the essential oil of aerial parts of Geranium macrorrhizum L. (Geraniaceae). The structures of the epoxy derivatives were deduced from their 1D‐ and 2D‐NMR spectra, molecular modeling, and confirmed by synthesis starting from germacrone. The epoxy compounds were screened for their antimicrobial activities by a microdilution assay, which revealed high activities of both compounds against Bacillus subtilis (minimum inhibitory concentrations (M/Cs) determined were 4.3 and 43 nmol/ml for 1,10‐ and 4,5‐epoxygermacrone, resp.) and Pseudomonas aeruginosa (0.043 and 0.855 μmol/ml for 1,10‐ and 4,5‐epoxygermacrone, resp.). The discovery and observed activity of the two epoxides fills the gap in our knowledge of the active principles in this highly renowned ethnomedicinal plant species.     

Floral symmetry is associated with flower size and pollen production but not insect visitation rates in Geranium robertianum (Geraniaceae)

The degree to which fine‐scaled variation in floral symmetry is associated with variation in plant fitness remains unresolved, as does the question of whether floral symmetry is in itself a target of pollinator‐mediated selection. Geranium robertianum (Geraniaceae) is a broadly distributed species whose five‐petaled flowers vary widely with respect to their degree of rotational asymmetry. In this study, we used a naturally occurring population of plants to investigate whether floral rotational asymmetry and leaf bilateral symmetry were phenotypically correlated with a series of fitness‐related traits, and also used an experimental array with model flowers to investigate the preference of insect visitors for varying degrees of floral size and symmetry. We found that leaf asymmetry was not associated with any of the phenotypic traits measured, and that the degree of floral rotational asymmetry was strongly associated with decreased flower size and decreased pollen production. Our experimental arrays showed that insect visitors did not discriminate among model flowers on the basis of size or symmetry alone; however, insect visitors preferentially visited smaller, symmetric model flowers over larger, severely asymmetric model flowers. Taken together, our results suggest that floral and leaf symmetry in G. robertianum are not likely strong indicators of phenotypic quality, and that floral symmetry is unlikely to be a target of pollinator‐mediated selection. However, the relationship between floral asymmetry and pollen production may provide a role for fecundity selection on symmetry in this species. These data importantly add to the growing literature on the adaptive nature of floral symmetry in the wild.     

Physiology of ecotypic plant response to sulfur dioxide in Geranium carolinianum L.

Summary Populations of Geranium carolinianum, a winter annual plant common in disturbed habitats, vary in their foliar response to sulfur dioxide, and pollution resistance is characteristic of populations sampled from areas in which SO₂ has been a prominent stress. The physiological basis of this ecotypic response was investigated using a whole-plant gaseous exchange system in which leaf resistance to H₂O efflux and SO₂ influx were concurrently monitored. Individual plants of distinct SO₂ susceptibility were exposed to pollutant concentrations of either 0.4, 0.6 or 0.8 l 1^-1 in both the dark and light. Total SO₂ flux (g cm^-2 h^-1) to the plant, which is the sum of leaf adsorptive and absorptive loss, varied as an inverse function of leaf resistance (s cm^-1), and the relationship was modeled using linear regression techniques. Total SO₂ flux was partitioned to leaf surface and internal fractions using estimation procedures with the regression analysis. SO₂ flux into the leaf interior, the pollutant fraction responsible for causing foliar injury, was strikingly similar for resistant and sensitive plants at each concentration. Resistant plants must absorb 30% more SO₂ than their sensitive counterparts in order to exhibit comparable levels of foliar injury. Therefore, in G. carolinianum the predominant explantation for genetically controlled and quantitatively inherited differences in plant résponse to SO₂ is not variable pollutant flux but rather disparate physiological-biochemical processes affecting pollutant toxicity, cellular perturbation and repair. This conclusion is relevant to understanding how populations of G. carolinianum respond over time to elevated levels of SO₂ and may explain the inherent susceptibility of this species compared with plants with which it co-exists.     

Biologically active constituents of a polyphenol extract from Geranium sanguineum L. with anti-influenza activity

From the aerial roots of the medicinal plant Geranium sanguineum L. a polyphenol-rich extract with strong anti-influenza activity has been isolated. To investigate its active fractions, the extract was partitioned by solvents with increasing polarity. The n-BuOH fraction contained the majority of the in vitro antiviral activity; the EtOAc fraction was the most effective one in vivo. A bioassay-directed fractionation of the n-BuOH and EtOAc fractions was performed to obtain information about the nature of the chemical components of the plant extract, responsible for the antiviral effect. The individual constituents were identified by spectroscopic methods and comparison with authentic samples and by HPLC. The cell-toxic and virus-inhibitory effects of the fractions and some individual polyphenol compounds, found in Geranium sanguineum L., were studied using the replication of representative influenza viruses in cell cultures. This study showed that the presence of a variety of biologically active compounds as well as the possible synergistic interactions between them seem to be decisive for the overall antiviral effect.     

547. Geranium Christensenianum

Summary.  The discovery, taxonomic history and affinities of Geranium christensenianum Handel‐Mazzetti are described. Its recent introduction and cultivation requirements are discussed.     

Geranium macrorrhizum L. (Geraniaceae) essential oil: a potent agent against Bacillus subtilis

The volatile hydrodistilled compounds from aerial parts and rhizomes of the ethnopharmacologically highly valued plant species Geranium macrorrhizum L. were screened for their antimicrobial activity in disc‐diffusion and microdilution assays. The assays pointed out to a very high and selective activity of the oils against Bacillus subtilis with minimum inhibitory concentrations (MIC) of 0.4–1.0 μg/ml. This prompted us to perform detailed compositional analyses of the oils. GC and GC/MS analyses allowed the identification of 283 constituents. The oils consisted mainly of sesquiterpenoids, the main ones being germacrone (49.7% in the oil from aerial parts) and δ‐guaiene (49.2% in rhizome oil). Significant qualitative and quantitative compositional differences in the oils from the two plant parts were observed. Further antimicrobial testing enabled us to determine that germacrone, the major constituent of the oil from aerial parts, was not the sole agent responsible for the observed activity.     

Geranium ruthenicum (sp. n.)

Sans résuméCfr. Oest. bot. Ztschr. XXII, p. 370.     

Chemotaxonomy of Geranium

The species of Geranium show a wide range of flavonoid pattern, from one in which ail the regular (primitive) constituents are present to one where only quercetin and kaempferol are present. The primitive pattern predominates in the central Eurasian area, radiating eastward and westward from which the flavonoid constituents become progressivley impoverished. A "flavonoid score" providing a numerical estimate of this impoverishment is proposed. The results are presented and discussed in relation to Knuth's arrangement of the genus.