Seed micromorphology and its taxonomic evidence in subfamily Alsinoideae (Caryophyllaceae).

Seed micromorphology of 13 species, belonging to four genera of subfamily Alsinoideae (Caryophyllaceae) were investigated with scanning electron microscopy (SEM), in order to assess their diagnostic significance at generic level and provide additional evidence on species delimitation, as well as correct identification and phylogenetic position. Genera and species of subfamily Alsinoideae exhibit great variation in ultrastructure and a high diversity of novel micromorphological characters were observed. Variation in seed shape, color, hilum, anticlinal wall, epidermal cell, cell surface, margins, and quantitative characters as length and width were studied in detail, compared, illustrated, and their taxonomic significant were discussed. Seed shapes of the species were classified as reniform, round, angular, subcircular, subreniform, and elliptical pyriform, with sub-central, central, basal, and nearly basal hilum. Wavy, irregular, tetragonal, and elongated epidermal cells structure has been observed as an exomorphological character. The present findings show that the micromorphology of subfamily Alsinoideae provides taxonomic information and is helpful to distinguish different species. The results also explained that SEM morphology of seeds provide important data about affinity among taxa and give potential characters in delimitation of members of subfamily Alsinoideae at generic and species level. A principal component analysis allowed to highlight the most outsiders among seed micromorphology with a possible explanation. Taxonomic keys were developed based on micromorphological characters to delimit the species and useful for their quick identification within subfamily Alsinoideae.

Using multiple microscopic techniques for the comparative systematic of Spergula fallax and Spergula arvensis (Caryophyllaceae).

In this study, comparative morphology, foliar anatomy and palynology of Spergula fallax and Spergula arvensis (Caryophyllaceae) were studied using multiple microscopic techniques. Genus Spergula includes worldwide five species, while in Flora of Pakistan the genus has two species. In this research, the comparative morphological, anatomical, and palynological characters of the two Pakistani Spergula species were studied. We examined some distinguishing morphological features, in both species, such as plant size, habitat, leaf morphological characters, inflorescences, flowers outer whorls, sepals and petals, and flowers number. These characters species were studied analyzing their comparative systematic significant. The foliar anatomical features also provided distinctive characters as the epidermal cell shape, the wall of the epidermal cell, lobes per cell. The differences in quantitative characters were also examined. The palynological characters showed difference in echini arrangement, echini density, and numbers of pore. Quantitative characters were variations in size of polar, equatorial, exine thickness, pore length, and width and P/E ratio. The multiple microscopic techniques provided sufficient evidence about the systematics of the genus Spergula. Based on morphological, anatomical, and palynological characters, analytical keys were developed for the identification and distinction of the species S. fallax and S. arvensis.

Leaf anatomy of two reciprocally non-monophyletic mountain plants (Heliosperma spp.): does heritable adaptation to divergent growing sites accompany the onset of speciation?

Evolution is driven by natural selection, favouring individuals adapted in phenotypic traits to the environmental conditions at their growing site. To shed light on ecological and (epi-) genetically based differentiation between Heliosperma pusillum and Heliosperma veselskyi, two reciprocally non-monophyletic, but morphologically and ecologically divergent species from the south-eastern Alps, we studied various leaf anatomical traits and investigated chloroplast ultrastructure in leaves of the two species grown either in their natural habitat or in a common garden. The alpine H. pusillum occurs in open, wet rock habitats, whereas its close relative H. veselskyi is restricted to dry, shady habitats below overhanging rocks in the montane belt. H. pusillum exhibited higher thickness of leaves and palisade layers as adjustments and/or adaptations to higher irradiance and a higher stomatal area index reflecting better water availability. Traits were adjusted plastically, but differed between species grown in a common garden, suggesting that the differentiation between the two species is not solely based on phenotypic plasticity but also has a genetic basis. Our study thus supports the hypothesis that differentiation between the highly interfertile species is likely driven by natural selection.

A Novel Bioinspired Continuous Unidirectional Liquid Spreading Surface Structure from the Peristome Surface of Nepenthes alata.

A novel unidirectional liquid spreading surface with an inclined arc pitted groove, inspired by the continuous unidirectional liquid spreading mechanism on the peristome surface of N. alata, is explored and fabricated by two-step UV lithography. Its superior unidirectional liquid spreading capability to that of other surface patterns is demonstrated, and its unidirectional liquid spreading mechanism is investigated.

Diel Variation in Flower Scent Reveals Poor Consistency of Diurnal and Nocturnal Pollination Syndromes in Sileneae.

The composition of flower scent and the timing of emission are crucial for chemical communication between plants and their pollinators; hence, they are key traits for the characterization of pollination syndromes. In many plants, however, plants are assigned to a syndrome based on inexpensive to measure flower traits, such as color, time of flower opening, and shape. We compared day and night scents from 31 Sileneae species and tested for quantitative and semi-quantitative differences in scent among species classified a priori as diurnal or nocturnal. As most Sileneae species are not only visited by either diurnal or nocturnal animals as predicted by their syndrome, we hypothesized that, even if flower scent were preferentially emitted during the day or at night, most species also would emit some scents during the opposing periods of the day. This phenomenon would contribute to the generalized assemblage of flower visitors usually observed in Sileneae species. We found that diel variations of scent often were not congruent with the syndrome definition, but could partially be explained by taxonomy and sampling times. Most species emitted compounds with attractive potential to insects during both the night and day. Our results highlight the current opinion that syndromes are not watertight compartments evolved to exclude some flower visitors. Thus, important information may be lost when scents are collected either during day- or night-time, depending on the a priori classification of the species as diurnal or nocturnal.

Easy Come, Easy Go: Capillary Forces Enable Rapid Refilling of Embolized Primary Xylem Vessels.

Protoxylem plays an important role in the hydraulic function of vascular systems of both herbaceous and woody plants, but relatively little is known about the processes underlying the maintenance of protoxylem function in long-lived tissues. In this study, embolism repair was investigated in relation to xylem structure in two cushion plant species, Azorella macquariensis and Colobanthus muscoides, in which vascular water transport depends on protoxylem. Their protoxylem vessels consisted of a primary wall with helical thickenings that effectively formed a pit channel, with the primary wall being the pit channel membrane. Stem protoxylem was organized such that the pit channel membranes connected vessels with paratracheal parenchyma or other protoxylem vessels and were not exposed directly to air spaces. Embolism was experimentally induced in excised vascular tissue and detached shoots by exposing them briefly to air. When water was resupplied, embolized vessels refilled within tens of seconds (excised tissue) to a few minutes (detached shoots) with water sourced from either adjacent parenchyma or water-filled vessels. Refilling occurred in two phases: (1) water refilled xylem pit channels, simplifying bubble shape to a rod with two menisci; and (2) the bubble contracted as the resorption front advanced, dissolving air along the way. Physical properties of the protoxylem vessels (namely pit channel membrane porosity, hydrophilic walls, vessel dimensions, and helical thickenings) promoted rapid refilling of embolized conduits independent of root pressure. These results have implications for the maintenance of vascular function in both herbaceous and woody species, because protoxylem plays a major role in the hydraulic systems of leaves, elongating stems, and roots.

Nectar sugar composition of European Caryophylloideae (Caryophyllaceae) in relation to flower length, pollination biology and phylogeny.

Floral nectar composition has been explained as an adaptation to factors that are either directly or indirectly related to pollinator attraction. However, it is often unclear whether the sugar composition is a direct adaptation to pollinator preferences. Firstly, the lower osmolality of sucrose solutions means that they evaporate more rapidly than hexose solutions, which might be one reason why sucrose-rich nectar is typically found in flowers with long tubes (adapted to long-tongued pollinators), where it is better protected from evaporation than in open or short-tubed flowers. Secondly, it can be assumed that temperature-dependent evaporation is generally lower during the night than during the day so that selection pressure to secrete nectar with high osmolality (i.e. hexose-rich solutions) is relaxed for night-active flowers pollinated at night. Thirdly, the breeding system may affect selection pressure on nectar traits; that is, for pollinator-independent, self-pollinated plants, a lower selective pressure on nectar traits can be assumed, leading to a higher variability of nectar sugar composition independent of pollinator preferences, nectar accessibility and nectar protection. To analyse the relations between flower tube length, day vs. night pollination and self-pollination, the nectar sugar composition was investigated in 78 European Caryophylloideae (Caryophyllaceae) with different pollination modes (diurnal, nocturnal, self-pollination) using high-performance liquid chromatography (HPLC). All Caryophylleae species (Dianthus and relatives) were found to have nectar with more than 50% sucrose, whereas the sugar composition of Sileneae species (Silene and relatives) ranged from 0% to 98.2%. In the genus Silene, a clear dichotomous distribution of sucrose- and hexose-dominant nectars is evident. We found a positive correlation between the flower tube length and sucrose content in Caryophylloideae, particularly in day-flowering species, using both conventional analyses and phylogenetically independent contrasts.

Androecial evolution in Caryophyllales in light of a paraphyletic Molluginaceae.

PREMISE OF THE STUDY: Caryophyllales are highly diverse in the structure of the perianth and androecium and show a mode of floral development unique in eudicots, reflecting the continuous interplay of gynoecium and perianth and their influence on position, number, and identity of the androecial whorls. The floral development of five species from four genera of a paraphyletic Molluginaceae (Limeum, Hypertelis, Glinus, Corbichonia), representing three distinct evolutionary lineages, was investigated to interpret the evolution of the androecium across Caryophyllales. • METHODS: Floral buds were dissected, critical-point dried and imaged with SEM. The genera studied are good representatives of the diversity of development of stamens and staminodial petaloids in Caryophyllales. • KEY RESULTS: Sepals show evidence of petaloid differentiation via marginal hyaline expansion. Corbichonia, Glinus, and Limeum also show perianth differentiation via sterilization of outer stamen tiers. In all four genera, stamens initiate with the carpels and develop centrifugally, but subsequently variation is significant. With the exception of Limeum, the upper whorl is complete and alternisepalous, while a second antesepalous whorl arises more or less sequentially, starting opposite the inner sepals. Loss or sterilization of antesepalous stamens occurs in Glinus and Limeum and is caused by altered carpel merism and inhibition by sepal pressures. • CONCLUSIONS: Outer stamens of Hypertelis correspond with petaloids of Caryophyllaceae and suggest that staminodial petaloids and outer alternisepalous stamens are interchangeable in the Caryophyllales. We emphasize a switch in the position of first formed stamens from antesepalous to alternisepalous following the divergence of Limeum; thus stamen position is an important synapomorphy for the globular inclusion clade.

An analytic model of the self-sealing mechanism of the succulent plant Delosperma cooperi.

After an injury, wound-sealing in leaves of the succulent plant Delosperma cooperi takes place by deformation and movement of the entire leaf within a time span of 30-60 min. In cross sections the almost cylindrical leaves reveal a centripetal arrangement of five different tissue types. Based on anatomical data and mechanical analyses of the five hulls, representing the different tissue layers, we present an analytical model describing the self-sealing process. The inclusion of viscoelastic aspects into the models enables to predict the temporal development of the self-sealing process. The formulation of the model in terms of closed functions facilitates: (i) sensitivity studies and (ii) the transfer of the model to technical systems which are based on non-biological materials.

Form follows function: morphological diversification and alternative trapping strategies in carnivorous Nepenthes pitcher plants.

Carnivorous plants of the genus Nepenthes have evolved a striking diversity of pitcher traps that rely on specialized slippery surfaces for prey capture. With a comparative study of trap morphology, we show that Nepenthes pitcher plants have evolved specific adaptations for the use of either one of two distinct trapping mechanisms: slippery wax crystals on the inner pitcher wall and 'insect aquaplaning' on the wet upper rim (peristome). Species without wax crystals had wider peristomes with a longer inward slope. Ancestral state reconstructions identified wax crystal layers and narrow, symmetrical peristomes as ancestral, indicating that wax crystals have been reduced or lost multiple times independently. Our results complement recent reports of nutrient source specializations in Nepenthes and suggest that these specializations may have driven speciation and rapid diversification in this genus.

Asymmetrical gene flow in a hybrid zone of Hawaiian Schiedea (Caryophyllaceae) species with contrasting mating systems.

Asymmetrical gene flow, which has frequently been documented in naturally occurring hybrid zones, can result from various genetic and demographic factors. Understanding these factors is important for determining the ecological conditions that permitted hybridization and the evolutionary potential inherent in hybrids. Here, we characterized morphological, nuclear, and chloroplast variation in a putative hybrid zone between Schiedea menziesii and S. salicaria, endemic Hawaiian species with contrasting breeding systems. Schiedea menziesii is hermaphroditic with moderate selfing; S. salicaria is gynodioecious and wind-pollinated, with partially selfing hermaphrodites and largely outcrossed females. We tested three hypotheses: 1) putative hybrids were derived from natural crosses between S. menziesii and S. salicaria, 2) gene flow via pollen is unidirectional from S. salicaria to S. menziesii and 3) in the hybrid zone, traits associated with wind pollination would be favored as a result of pollen-swamping by S. salicaria. Schiedea menziesii and S. salicaria have distinct morphologies and chloroplast genomes but are less differentiated at the nuclear loci. Hybrids are most similar to S. menziesii at chloroplast loci, exhibit nuclear allele frequencies in common with both parental species, and resemble S. salicaria in pollen production and pollen size, traits important to wind pollination. Additionally, unlike S. menziesii, the hybrid zone contains many females, suggesting that the nuclear gene responsible for male sterility in S. salicaria has been transferred to hybrid plants. Continued selection of nuclear genes in the hybrid zone may result in a population that resembles S. salicaria, but retains chloroplast lineage(s) of S. menziesii.

Origami-like unfolding of hydro-actuated ice plant seed capsules.

Actuated plant materials are a source of inspiration for the design of adaptive materials and structures that are responsive to specific external stimuli. Hydro-responsive, metabolism-independent plant movements are particularly fascinating, because the extracted concepts are more amenable to transfer into engineering than those dependent on cellular activity. Here we investigate the structural and compositional basis of a sophisticated plant movement mechanism--the hydration-dependent unfolding of ice plant seed capsules. This reversible origami-like folding pattern proceeds via a cooperative flexing-and-packing mechanism actuated by a swellable cellulose layer filling specialized plant cells. Swelling is translated into a bidirectional organ movement through simple geometric constraints embedded in the hierarchical architecture of the ice plant valves. Extracted principles from this reliable and reversible actuated movement have relevance to the emerging field of 'programmable matter' with applications as far-reaching as the design of satellites and artificial muscles.

[Observation on biological characteristics of wild Pseudostellaria heterophylla].

OBJECTIVE: To study the status and regular pattern in growing development of wild Pseudostellaria heterophylla. METHODS: Observed and studied on wild Pseudostellaria heterophylla during growth periods continuously. RESULTS: The growing development of Pseudostellaria heterophylla could be divided into three stages: asexual reproduction stage, coexistence of asexual and sexual reproduction stage. In the first two years of seed germination, there was only asexual reproduction, from which substitute tuberous root and cauline tuberous root were formed; Afterward flowering and fructifying sexual reproduction occurred to the plant that had developed from tuberous root while it continued with asexual reproduction; Only sexual reproduction existed during the last year of the Pseudostellaria heterophylla plant before its death. The Pseudostellaria heterophylla plant above ground grew from early spring to late autumn and over-wintered with tuberous root. There were two patterns of asexual reproduction: substitution with tuberous root in spring and expanding of adventitious root on stolon into cauline tuberous root in autumn. All tuberous roots of Pseudostellaria heterophylla were originated from adventitious root; The existence of tuberous root was one year at most; The rapidly expanding period of tuberous root was during February and March. CONCLUSIONS: The results provide a reference for reformative cultivation of Pseudostellaria heterophylla.

Traps of carnivorous pitcher plants as a habitat: composition of the fluid, biodiversity and mutualistic activities.

BACKGROUND: Carnivorous pitcher plants (CPPs) use cone-shaped leaves to trap animals for nutrient supply but are not able to kill all intruders of their traps. Numerous species, ranging from bacteria to vertrebrates, survive and propagate in the otherwise deadly traps. This paper reviews the literature on phytotelmata of CPPs. PITCHER: Fluid as a Habitat The volumes of pitchers range from 0·2 mL to 1·5 L. In Nepenthes and Cephalotus, the fluid is secreted by the trap; the other genera collect rain water. The fluid is usually acidic, rich in O(2) and contains digestive enzymes. In some taxa, toxins or detergents are found, or the fluid is extremely viscous. In Heliamphora or Sarracenia, the fluid differs little from pure water. INQUILINE: Diversity Pitcher inquilines comprise bacteria, protozoa, algae, fungi, rotifers, crustaceans, arachnids, insects and amphibia. The dominant groups are protists and Dipteran larvae. The various species of CPPs host different sets of inquilines. Sarracenia purpurea hosts up to 165 species of inquilines, followed by Nepenthes ampullaria with 59 species, compared with only three species from Brocchinia reducta. Reasons for these differences include size, the life span of the pitcher as well as its fluid. MUTUALISTIC: Activities Inquilines closely interact with their host. Some live as parasites, but the vast majority are mutualists. Beneficial activities include secretion of enzymes, feeding on the plant's prey and successive excretion of inorganic nutrients, mechanical break up of the prey, removal of excessive prey and assimilation of atmospheric N(2). CONCLUSIONS: There is strong evidence that CPPs influence their phytotelm. Two strategies can be distinguished: (1) Nepenthes and Cephalotus produce acidic, toxic or digestive fluids and host a limited diversity of inquilines. (2) Genera without efficient enzymes such as Sarracenia or Heliamphora host diverse organisms and depend to a large extent on their symbionts for prey utilization.

Induced production of antifungal naphthoquinones in the pitchers of the carnivorous plant Nepenthes khasiana.

Nepenthes spp. are carnivorous plants that have developed insect capturing traps, evolved by specific modification of the leaf tips, and are able to utilize insect degradation products as nutritional precursors. A chitin-induced antifungal ability, based on the production and secretion to the trap liquid of droserone and 5-O-methyldroserone, is described here. Such specific secretion uniquely occurred when chitin injection was used as the eliciting agent and probably reflects a certain kind of defence mechanism that has been evolved for protecting the carnivory-based provision of nutritional precursors. The pitcher liquid containing droserone and 5-O-methyldroserone at 3:1 or 4:1 molar ratio, as well as the purified naphthoquinones, exerted an antifungal effect on a wide range of plant and human fungal pathogens. When tested against Candida and Aspergillus spp., the concentrations required for achieving inhibitory and fungicidal effects were significantly lower than those causing cytotoxicity in cells of the human embryonic kidney cell line, 293T. These naturally secreted 1,4-naphthoquinone derivatives, that are assumed to act via semiquinone enhancement of free radical production, may offer a new lead to develop alternative antifungal drugs with reduced selectable pressure for potentially evolved resistance.

[Anther development and sperm isolation of Pseudostellaria heterophylla (Miq.)].

Anther wall is general and tapetum is glandular. The process of meiosis of microspore mother cells is simultaneous and the tetrads are tetrahedral. The mature pollen of Pseudostellaria heterophylla (Miq.) is tree-celled. There are 22-30 germ pores on the pollen wall. Many pollen grains could burst in 10% mannitol or 15% sucrose solution and release a pair of sperm cells which could keep alive for 25-50 min by FDA fluorescence. Using micromanipulator the released sperm cells could be collected. When pollen grains were put into a solution containing 0.03% CaCl2, 0.01% H3BO3, 0.01% KH2PO4 and 20% PEG for 2-5 min, they would germinate and the pollen tubes would reach 815 microm at 2h after cultured. A pair of sperms would enter into pollen tube when it grew to 500-600 microm. The fluorescence of both sperms would be observed clearly in pollen tube after DAPI staining. When the pollen tubes were burst in a bursting solution, a pair of sperms would be released from pollen tube.

Structural studies of arabinogalactan and pectin from Silene vulgaris (M.) G. Callus.

Arabinogalactan and pectin (named silenan) were isolated from Silene vulgaris (M.) G. callus. Fractionation by ion-exchange chromatography on DEAE-cellulose and digestion with pectinase demonstrated that silenan from S. vulgaris callus (80% of D-galacturonic acid) and silenan from the aerial part of the campion S. vulgaris are similar: both pectins contain a high quantity of homogalacturonan segments. The NMR spectral data and mass spectrometry of the purified polysaccharide and its fragment obtained by Smith degradation confirmed that the core of the arabinogalactan consisted of the different segments of beta-1,3-D-galactopyranan. Some of the beta-galactopyranose residues of the backbone are branched at O-6. The side chains of the arabinogalactan were shown to contain residues of terminal and 3-O-substituted beta-galactopyranose, terminal alpha-arabinofuranose and alpha-rhamnopyranose, and 2-O-substituted alpha-rhamnopyranose. The alpha-rhamnopyranose residues in the sugar chain appeared to be 2-O-glycosylated by the beta-1,4-D-galactopyranosyl uronic acid residues.

[Growth comparison among Psammosilene tunicoides populations in tissue culture].

The comparison between the growth of eight populations from Psammosilene tunicoides at Yunnan Province was made by the tissue culture. The initial results showed out two populations from Yunshanping (Lijiang) and Xiaomoyu (Kunming) was dominant than orthers. It would be regard as one of fine germplasm resources for the culture of Psammosilence tunicoides.

Comparative anatomy of gall development on Gypsophila paniculata induced by bacteria with different mechanisms of pathogenicity.

Galls induced on Gypsophila paniculata by Pantoea agglomerans pv. gypsophilae (Pag) and Agrobacterium tumefaciens (At), bacteria with different mechanisms of pathogenicity, were compared morphologically and anatomically. The pathogenicity of Pag is dependent on the presence of an indigenous plasmid that harbors hrp gene cluster, genes encoding Hop virulence proteins and biosynthetic genes for auxin (IAA) and cytokinins (CKs), whereas that of At involves host transformation. The Pag-induced gall was rough, brittle and exhibited limited growth, in contrast to the smooth, firm appearance and continuous growth of the At-induced gall. Anatomical analysis revealed the presence of cells with enlarged nuclei and multiple nucleoli, giant cells and suberin deposition in Pag that were absent from At-induced galls. Although circular vessels were observed in both gall types, they were more numerous and the vascular system was more organized in At. An aerenchymal tissue was observed in the upper part of the galls. Ethylene emission from Pag galls, recorded 6 days after inoculation, was eight times as great as that from non-infected controls. In contrast, a significant decrease in ethylene production was observed in Gypsophila cuttings infected with Pag mutants deficient in IAA and CK production. The results presented are best accounted for by the two pathogens having distinct pathogenicity mechanisms that lead to their differential recognition by the host as non-self (Pag) and self (At).

[Studies on strain characteristics of Pseudostellaria heterophylla varieties].

OBJECTIVE: To characterize the different varieties of Pseudostellaria heterophylla during cultivation. METHOD: Using systematic selection in the main productive areas, the techniques of random design, all varieties were observed for 3 years. RESULT: The biological and 425 productive characteristics of P. heterophylla var. macrophylla, P. heterophylla var. Foliolum, and P. heterophylla var. anvense were significantly different (P < 0.01). There were also differences in ecological adaptability, plant characteristics, pollen granule, chromosomes, and isoenzyme of the three cultivars. CONCLUSION: The strain types of P. heterophylla was denominated for the first time. The characteristics and productivity index system of P. heterophylla varieties were determined.