Spatio-Temporal Distribution of Cell Wall Components in the Placentas, Ovules and Female Gametophytes of Utricularia during Pollination.

In most angiosperms, the female gametophyte is hidden in the mother tissues and the pollen tube enters the ovule via a micropylar canal. The mother tissues play an essential role in the pollen tube guidance. However, in Utricularia, the female gametophyte surpasses the entire micropylar canal and extends beyond the limit of the integument. The female gametophyte then invades the placenta and a part of the central cell has direct contact with the ovary chamber. To date, information about the role of the placenta and integument in pollen tube guidance in Utricularia, which have extra-ovular female gametophytes, has been lacking. The aim of this study was to evaluate the role of the placenta, central cell and integument in pollen tube pollen tube guidance in Utricularia nelumbifolia Gardner and Utricularia humboldtii R.H. Schomb. by studying the production of arabinogalactan proteins. It was also determined whether the production of the arabinogalactan proteins is dependent on pollination in Utricularia. In both of the examined species, arabinogalactan proteins (AGPs) were observed in the placenta (epidermis and nutritive tissue), ovule (integument, chalaza), and female gametophyte of both pollinated and unpollinated flowers, which means that the production of AGPs is independent of pollination; however, the production of some AGPs was lower after fertilization. There were some differences in the production of AGPs between the examined species. The occurrence of AGPs in the placental epidermis and nutritive tissue suggests that they function as an obturator. The production of some AGPs in the ovular tissues (nucellus, integument) was independent of the presence of a mature embryo sac.

Genlisea hawkingii (Lentibulariaceae), a new species from Serra da Canastra, Minas Gerais, Brazil.

Genlisea hawkingii, which is a new species of Genlisea subgen. Tayloria (Lentibulariaceae) from cerrado in southwest Brazil, is described and illustrated. This species has been found in only one locality thus far, in the Serra da Canastra, which is located in the Delfinópolis municipality in Minas Gerais, Brazil. The new species is morphologically similar to Genlisea violacea and G. flexuosa, but differs from them in having a corolla with a conical and curved spur along with sepals with an acute apex and reproductive organs that only have glandular hairs. Moreover, it is similar to G. uncinata's curved spur. G. hawkingii is nested within the subgen. Tayloria clade as a sister group to all the other species of this subgenus. Therefore, both morphological and phylogenetic results strongly support G. hawkingii as a new species in the subgen. Tayloria.

Potential for chromium (VI) bioremediation by the aquatic carnivorous plant Utricularia gibba L. (Lentibulariaceae).

The aquatic carnivorous plant Utricularia gibba has one of the smallest known genomes among flowering plants, and therefore, it is an excellent model organism for physiological and developmental studies. The main aim of our work was to check whether the ubiquitous U. gibba might be useful for the phytoremediation of the highly toxic and mobile hexavalent chromium in waters. Plants were incubated for 1 week in a 50 µM (2.6 mg dm(-3)) Cr(VI) solution in laboratory conditions. Our results revealed that the plant exhibits a very high accumulation capacity for Cr. The accumulation level was higher than 780 mg kg(-1) and a bioconcentration factor >300. On the other hand, the plants showed a low tolerance to the elevated Cr concentration, which was expressed in a significant decrease of the photosystem II activity. However, the most pronounced negative influence of chromate was found on the morphology and activity of the traps. Due to its high accumulation capacity, we suggest that U. gibba may be efficient in the removal of chromate over a short time scale. It can also provide a new molecular resource for studying the mechanisms of Cr(VI) detoxification.

New data about the functional morphology of the chaetiferous leech-like annelids Acanthobdella peledina (Grube, 1851) and Paracanthobdella livanowi (Epshtein, 1966) (Clitellata, Acanthobdellida).

Approximately 130 individuals of Acanthobdella peledina and 100 individuals of Paracanthobdella livanowi were studied. Morphometric measurements were taken to explore the body form. The digestive and the reproductive systems of leech-like annelids were analyzed for the first time in such a high number of specimens. Observation of A. peledina and P. livanowi revealed crucial differences in the reproductive system of the analyzed taxa, mostly regarding variation in the shape of the testisacs and the length of the ovisacs. The results of a digestive system analysis suggest that blood-sucking parasites of the order Acanthobdellida may also lead a predatory lifestyle. The presented findings support the taxonomic division of the order Acanthobdellida into the families Acanthobdellidae and Paracanthobdellidae. Multiple similarities between Acanthobdellida and Hirudinida were also discussed.

Are there symplastic connections between the endosperm and embryo in some angiosperms?--a lesson from the Crassulaceae family.

It is believed that there is symplastic isolation between the embryo (new sporophyte) and the endosperm (maternal-parental origin tissue, which nourishes the embryo) in angiosperms. However, in embryological literature there are rare examples in which plasmodesmata between the embryo suspensor and endosperm cells have been recorded (three species from Fabaceae). This study was undertaken in order to test the hypothesis that plasmodesmata between the embryo suspensor and the endosperm are not so rare but also occur in other angiosperm families; in order to check this, we used the Crassulaceae family because embryogenesis in Crassulaceae has been studied extensively at an ultrastructure level recently and also we tread members of this family as model for suspensor physiology and function studies. These plasmodesmata even occurred between the basal cell of the two-celled proembryo and endosperm cells. The plasmodesmata were simple at this stage of development. During the development of the embryo proper and the suspensor, the structure of plasmodesmata changes. They were branched and connected with electron-dense material. Our results suggest that in Crassulaceae with plasmodesmata between the endosperm and suspensor, symplastic connectivity at this cell-cell boundary is still reduced or blocked at a very early stage of embryo development (before the globular stage). The occurrence of plasmodesmata between the embryo suspensor and endosperm cells suggests possible symplastic transport between these different organs, at least at a very early stage of embryo development. However, whether this transport actually occurs needs to be proven experimentally. A broader analysis of plants from various families would show whether the occurrence of plasmodesmata between the embryo suspensor and the endosperm are typical embryological characteristics and if this is useful in discussions about angiosperm systematic and evolution.

New data about the suspensor of succulent angiosperms: Ultrastructure and cytochemical study of the embryo-suspensor of Sempervivum arachnoideum L. and Jovibarba sobolifera (Sims) Opiz.

The development of the suspensor in two species - Sempervivum arachnoideum and Jovibarba sobolifera - was investigated using cytochemical methods, light and electron microscopy. Cytological processes of differentiation in the embryo-suspensor were compared with the development of embryo-proper. The mature differentiated suspensor consists of a large basal cell and three to four chalazal cells. The basal cell produces haustorial branched invading ovular tissues. The walls of the haustorium and the micropylar part of the basal cell form the wall ingrowths typical for a transfer cells. The ingrowths also partially cover the lateral wall and the chalazal wall separating the basal cell from the other embryo cells. The dense cytoplasm filling the basal cell is rich in: numerous polysomes lying free or covering rough endoplasmic reticulum (RER), active dictyosomes, microtubules, bundles of microfilaments, microbodies, mitochondria, plastids and lipid droplets. Cytochemical tests (including proteins, insoluble polysaccharides and lipids are distributed in the suspensor during different stages of embryo development) showed the presence of high amounts of macromolecules in the suspensor cells, particularly during the globular and heart-shaped phases of embryo development. The protein bodies and lipid droplets are the main storage products in the cells of the embryo-proper. The results of Auramine 0 indicate that a cuticular material is present only on the surface walls of the embryo-proper, but is absent from the suspensor cell wall. The ultrastructural features and cytochemical tests indicate that in the two species - S. arachnoideum and J. sobolifera - the embryo-suspensor is mainly involved in the absorption and transport of metabolites from the ovular tissues to the developing embryo-proper.

Actin cytoskeleton in the extra-ovular embryo sac of Utricularia nelumbifolia (Lentibulariaceae).

The actin cytoskeleton in the mature female gametophyte of angiosperms has been examined in only a few dicot and monocot species. The main purposes of this study were to identify how the actin cytoskeleton is arranged in the mature extra-ovular embryo sac in Utricularia nelumbifolia (Lentibulariaceae). We found that the extra-ovular part of the central cell has a well-developed actin cytoskeleton: actin microfilaments formed of long strands which run longitudinally or transversally to the long axis of the embryo sac. The exerted part of the central cell, which is exposed to the environment of the ovary chamber, is highly vacuolated and in the thin peripheral cytoplasm possesses a complicated network of actin microfilaments. The epidermal cells of the placenta that are in contact with the extra-ovular part of the embryo sac are crushed. The ultrastructure data of these cells are presented. We detected the accumulation of the actin cytoskeleton between the micropylar parts of the synergids and the extra-ovular part of central cell. This actin accumulation is unusual because in typical angiosperms the micropylar parts of the synergids form the apex of the female gametophyte.

Female germ unit in Genlisea and Utricularia, with remarks about the evolution of the extra-ovular female gametophyte in members of Lentibulariaceae.

Lentibulariaceae is the largest family among carnivorous plants which displays not only an unusual morphology and anatomy but also the special evolution of its embryological characteristics. It has previously been reported by authors that Utricularia species lack a filiform apparatus in the synergids. The main purposes of this study were to determine whether a filiform apparatus occurs in the synergids of Utricularia and its sister genus Genlisea, and to compare the female germ unit in these genera. The present studies clearly show that synergids in both genera possess a filiform apparatus; however, it seems that Utricularia quelchii synergids have a simpler structure compared to Genlisea aurea and other typical angiosperms. The synergids are located at the terminal position in the embryo sacs of Pinguicula, Genlisea and were probably also located in that position in common Utricularia ancestor. This ancestral characteristic still occurs in some species from the Bivalvaria subgenus. An embryo sac, which grows out beyond the limit of the integument and has contact with nutritive tissue, appeared independently in different Utricularia lineages and as a consequence of this, the egg apparatus changes position from apical to lateral.

The F-actin cytoskeleton in syncytia from non-clonal progenitor cells.

The actin cytoskeleton of plant syncytia (a multinucleate cell arising through fusion) is poorly known: to date, there have only been reports about F-actin organization in plant syncytia induced by parasitic nematodes. To broaden knowledge regarding this issue, we analyzed F-actin organization in special heterokaryotic Utricularia syncytia, which arise from maternal sporophytic tissues and endosperm haustoria. In contrast to plant syncytia induced by parasitic nematodes, the syncytia of Utricularia have an extensive F-actin network. Abundant F-actin cytoskeleton occurs both in the region where cell walls are digested and the protoplast of nutritive tissue cells fuse with the syncytium and also near a giant amoeboid in the shape nuclei in the central part of the syncytium. An explanation for the presence of an extensive F-actin network and especially F-actin bundles in the syncytia is probably that it is involved in the movement of nuclei and other organelles and also the transport of nutrients in these physiological activity organs which are necessary for the development of embryos in these unique carnivorous plants. We observed that in Utricularia nutritive tissue cells, actin forms a randomly arranged network of F-actin, and later in syncytium, two patterns of F-actin were observed, one characteristic for nutritive cells and second-actin bundles-characteristic for haustoria and suspensors, thus syncytia inherit their F-actin patterns from their progenitors.

Mineral nutrient uptake from prey and glandular phosphatase activity as a dual test of carnivory in semi-desert plants with glandular leaves suspected of carnivory.

BACKGROUND AND AIMS: Ibicella lutea and Proboscidea parviflora are two American semi-desert species of glandular sticky plants that are suspected of carnivory as they can catch small insects. The same characteristics might also hold for two semi-desert plants with glandular sticky leaves from Israel, namely Cleome droserifolia and Hyoscyamus desertorum. The presence of proteases on foliar hairs, either secreted by the plant or commensals, detected using a simple test, has long been considered proof of carnivory. However, this test does not prove whether nutrients are really absorbed from insects by the plant. To determine the extent to which these four species are potentially carnivorous, hair secretion of phosphatases and uptake of N, P, K and Mg from fruit flies as model prey were studied in these species and in Roridula gorgonias and Drosophyllum lusitanicum for comparison. All species examined possess morphological and anatomical adaptations (hairs or emergences secreting sticky substances) to catch and kill small insects. METHODS: The presence of phosphatases on foliar hairs was tested using the enzyme-labelled fluorescence method. Dead fruit flies were applied to glandular sticky leaves of experimental plants and, after 10-15 d, mineral nutrient content in their spent carcasses was compared with initial values in intact flies after mineralization. KEY RESULTS: Phosphatase activity was totally absent on Hyoscyamus foliar hairs, a certain level of activity was usually found in Ibicella, Proboscidea and Cleome, and a strong response was found in Drosophyllum. Roridula exhibited only epidermal activity. However, only Roridula and Drosophyllum took up nutrients (N, P, K and Mg) from applied fruit flies. CONCLUSIONS: Digestion of prey and absorption of their nutrients are the major features of carnivory in plants. Accordingly, Roridula and Drosophyllum appeared to be fully carnivorous; by contrast, all other species examined are non-carnivorous as they did not meet the above criteria.

Functional utrastructure of Genlisea (Lentibulariaceae) digestive hairs.

BACKGROUND AND AIMS: Digestive structures of carnivorous plants produce external digestive enzymes, and play the main role in absorption. In Lentibulariaceae, the ultrastructure of digestive hairs has been examined in some detail in Pinguicula and Utricularia, but the sessile digestive hairs of Genlisea have received very little attention so far. The aim of this study was to fill this gap by expanding their morphological, anatomical and histochemical characterization. METHODS: Several imaging techniques were used, including light, confocal and electron microscopy, to reveal the structure and function of the secretory hairs of Genlisea traps. This report demonstrates the application of cryo-SEM for fast imaging of whole, physically fixed plant secretory structures. KEY RESULTS AND CONCLUSION: The concentration of digestive hairs along vascular bundles in subgenus Genlisea is a primitive feature, indicating its basal position within the genus. Digestive hairs of Genlisea consist of three compartments with different ultrastructure and function. In subgenus Tayloria the terminal hair cells are transfer cells, but not in species of subgenus Genlisea. A digestive pool of viscous fluid occurs in Genlisea traps. In spite of their similar architecture, the digestive-absorptive hairs of Lentibulariaceae feature differences in morphology and ultrastructure.