Hydathode pit development in the alpine plant Saxifraga cochlearis (original) (raw)
Related papers
Flora, 2018
Some sections of species within the genus Saxifraga deposit a chalky crust on the surface of their leaves, originating from the guttation medium produced by the sunken hydathodes found generally at or near the leaf margin. The organisation of the hydathode tissues, that of the rest of the leaf and the physiology of the crust is poorly understood. We have used cryo-SEM and cryo-fracture to study leaf tissue organisation and structure in Saxifraga scardica and compared it to the imaging data with the previously characterised Saxifraga cochlearis. We find S. scardica contains a transparent and tapered leaf margin containing thick walled cylindrical cells that may serve to deflect light to the adjacent palisade mesophyll tissue. Raman microscopy reveals the S. scardica leaf crust contains the rare and metastable calcium carbonate polymorph vaterite whereas the crust from S. cochlearis contains only calcite. Vaterite-crust is also observed on the leaves of some species within the section Porphyrion but is not found on members of the section Ligulatae. The implications of these findings are discussed.
F1000 - Post-publication peer review of the biomedical literature
† Background and Aims Leaves of succulent Peperomia obtusifolia (Piperaceae), and its related species, contain a large multilayered hypodermis (epidermis) subtended by a very small single-layered photosynthetic palisade parenchyma, the latter containing spherical aggregates of crystals called druses. Each druse is in a central vacuole surrounded by chloroplasts. All hypodermal cell walls are thin, except for thick lowermost periclinal walls associated with the upper periclinal walls of the subtending palisade cells. These thick walls display 'quilted' impressions (mounds) formed by many subtending palisade cells. Conspicuous depressions occur in most mounds, and each depression contains what appear to be many plasmodesmata. These depressions are opposite similar regions in adjacent thin palisade periclinal walls, and they can be considered special pit fields that represent thin translucent regions ('windows' or 'skylights'). Druses in the vacuoles of palisade cells occur below these pit field regions and are surrounded by conspicuous cytoplasmic chloroplasts with massive grana oriented perpendicular to the crystals, probably providing for an efficient photosynthetic system under low-intensity light. † Methods Leaf clearings and fractures, light microscopy and crossed polarizers, general and histochemical staining, and transmission and scanning electron microscopy were used to examine these structures. † Key Results Druses in the vacuoles of palisade cells occur below the thin pit field regions in the wall interface, suggesting an interesting physical relationship that could provide a pathway for light waves, filtered through the multiple hypodermis. The light waves pass into the palisade cells and are collected and dispersed by the druses to surrounding chloroplasts with large grana. † Conclusions These results imply an intriguing possible efficient photosynthetic adaptation for species growing in low-light environments, and provide an opportunity for future research on how evolution through environmental adaptation aids plants containing crystals associated with photosynthetic tissues to exist under low-light intensity and with other stresses.
Annals of Botany, 2011
Aims The maternal gametophytic calyptra is critical for moss sporophyte development and ultimately sporogenesis. The calyptra has been predicted to protect the sporophyte apex, including the undifferentiated sporogenous region and seta meristem, from desiccation. We investigate the hypothesis that this waterproofing ability is due to a waxy cuticle. The idea that moss calyptrae are covered by a cuticle has been present in the literature for over a century, but, until now, neither the presence nor the absence of a cuticle has been documented for any calyptra. † Methods The epidermis of the calyptra, leafy gametophyte and sporophyte sporangia of the moss Funaria hygrometrica were examined using scanning and transmission electron microscopy. Thicknesses of individual cuticle layers were quantified and compared statistically. The immunochemistry antibody (LM19) specific for pectins was used to locate cell wall material within the cuticle. † Key Results A multi-layered cuticle is present on the calyptra of F. hygrometrica, including layers analogous to the cuticular layer, cell wall projections, electron-lucent and electron-dense cuticle proper observed in vascular plants. The calyptra rostrum has a cuticle that is significantly thicker than the other tissues examined and differs by specialized thickenings of the cuticular layer (cuticular pegs) at the regions of the anticlinal cell walls. This is the first documentation of cuticular pegs in a moss. † Conclusions The calyptra and its associated cuticle represent a unique form of maternal care in embryophytes. This organ has the potential to play a critical role in preventing desiccation of immature sporophytes and thereby may have been essential for the evolution of the moss sporophyte.
Leaf morphoanatomy of the rheophyte
2010
Leaf morphoanatomy of the rheophyte Dyckia distachya Hassler (Bromeliaceae) ABSTRACT: (Leaf morphoanatomy of the rheophyte Dyckia distachya Hassler (Bromeliaceae)). This research reports on the leaf morphoanatomy of the rheophyte Dyckia distachya. Plants with young and mature leaves of three populations from the Pelotas River and Uruguay River (SC, Brazil), which were maintained in a greenhouse, were utilized in the study. The leaves of D. distachya have sheaths, and the blades are lanceolate with serrate margins. The leaf epidermis of this species has a thickened cuticular membrane; thickened and lignified cellular walls, except in the outer periclinal; and silica bodies in the lumen. Tetracytic stomata are found within individual depressions that are protected by peltate scales; both the stomata and scales are restricted to the intercostal zones, on the abaxial surface. These features of the epidermis suggest that this species has the ability to conserve water while gas is exchanged during periods when the water level is low. The mesophyll is formed by the following: the hypodermis, which is made of septate fibers (along the adaxial surface and abaxial costal regions) or sclereids (abaxial intercostal regions); hydrenchyma, the widest tissue; chlorenchyma, located adaxially to the collateral vascular bundles; and aerenchyma, which communicate directly with the stomata. The leaf sheath has neither scales nor stomata. Dyckia distachya has both xeromorphic and hydromorphic features, which are associated with survival during periods when the water level is low or is high, respectively.
A Study on the Leaf Surfaces Micro-Morphological Characteristics in the Chenopodiaceae
International Journal of Sciences
The aim of the present study is to determine the micro-morphological properties of the leaf surfaces of nine species belonging to the family Chenopodiaceae, using scanning electron microscopy (SEM). Leaf surfaces were noticed to vary considerably with respect to cuticle structural types, stomatal pores position, guard cells cuticular ledges and types of trichomes. Lamellate and lamellate-reticulate cuticular types were recognized. These cuticular folds undergo various patterns, depth and orientation in the various species examined. Sunken, ridged, leveled, raised or depressed stomatal pores were encountered, whereas, the guard cells ledges were poorly or welldeveloped. In Suaeda vermiculata the stomatal pores are sunken in high longitudinal folds rendering the ledges indistinct. Non-glandular unbranched trichomes were detected in Bassia muricata, and collapsed salt bladders were reported in Atriplex leucoclada. The results showed that the micro-morphological characters of the leaf-surfaces examined are considered to be adaptations in response to arid conditions.
Nordic Journal of Botany, 2010
Cell lysis in the formation of secretory cavities in plants has been questioned by some authors and considered as result of technical artifacts. To describe the formation of secretory resin cavities in Hymenaea stigonocarpa leaves, leaflet samples at different stages of differentiation were collected, fixed, and processed for light and electron microscopy as per usual methods. The initial cells of secretory resin cavities are protodermal and grow towards the mesophyll ground meristem; these cells then divide producing cell groups that are distinguished by the shape and arrangement of cytoplasm, and density. At the initial stages of differentiation of the secretory cavities, some central cells in these groups show dark cytoplasm and condensed nuclear chromatin. Later, there is cell wall loosening, tonoplast and plasmalemma rupture resulting in cell death. These cells, however, maintain organelle integrity until lysis, when the cell wall degrades and the plasmalemma ruptures, releasing protoplast residues, marked characteristics of programmed cell death. The secretory epithelium remains active until complete leaf expansion when the cavity is filled with resin and the secretory activity ceases. There are no wall residues between central cells in adult cavities. Our results demonstrate lysigeny and the importance of ontogenetic studies in determining the origin of secretory cavities.
Comparative mophology and anatomy of the leaf
The genera and species of Piperaceae show a considerable structural diversity of leaves and especially stems. This paper presents a comparative morphological and anatomical study of the leaves and stems of three common Brazilian species of this family (Peperomia dahlstedtii C.DC., Ottonia martiana Miq. and Piper diospyrifolium Kunth), the vegetative organs of which have previously been little studied. The collected plant material was fixed in FAA, cut freehand and stained in safranin and astra blue. P. dahlstedtii is an epiphyte and has a herbaceous stem with whorled leaves phyllotaxis and a polystelic structure, a multiseriate adaxial leaf epidermis and calcium oxalate monocrystals in parenchyma and collenchyma petiole cells. O. martiana and P. diospyrifolium showed strong similarities, both being terrestrial plants, with alternate phyllotaxis, stele with medullary bundles and dorsiventral leaves with an epidermis and subepidermic layer. In O. martiana the stomatal complex is staurocytic and presented silica crystal sand in paren-chyma petiole and midrib cells. In P. diospyrifolium the stomatal complex is tetracytic and there are calcium oxalate raphide crystals in the parenchyma of the petiole and midrib cells. On the other hand, the three species show some structural likenesses in that all have hypostomatic and dorsiventral leaves, oily cells in petiole and mesophyll, secre-tory trichomes and an endodermis with Casparian strips. RESUMEN Los géneros y las especies de Piperaceae muestran una notoria diversidad estructural en sus hojas, y en particular en tallos. Este trabajo presente presenta un estudio comparativo morfológico y anatómico del tallo y hoja de tres especies de esta familia (Peperomia dahlstedtii C.DC., Ottonia martiana Miq. y Piper diospyrifolium Kunth) que son frecuen-tes en los bosques brasileños, sin que sus órganos vegetativos hubiesen sido previamente examinados anatómicamente. El material fue fijado en FAA, cortado a mano y coloreado con safranina y azul de astra. P. dahlstedtii es un epífito que posee un tallo herbáceo con filotaxia verticilada y estructura polistélica, hoja con epidermis adaxial multiseriada y monocristal de oxalato de calcio en células parenquimáticas y colenquimáticas del pecíolo. O. martiana y P. diospyrifolium presentan muchas semejanzas, siendo ambas plantas terrestres con filotaxia alterna, estela con haces medulares y hoja dorsiventral con epidermis y subepidermis. En O. martiana el aparato estomático es estaurocítico y presenta cristal de sílice en células parenquimáticas del pecíolo y vena media. En P. diospyrifolium el aparato estomá-tico es tetracítico con presencia de rafidios en la parénquima del pecíolo y vena media. Por otro lado, las tres especies muestran cierta semblanza estructural, como hojas hipostomáticas y dorsiventrales, células con aceite en el peciolo y lámina, tricomas glandulares y endodermis provista de banda de Caspary.
Distribution and Structure of Torus-Bearing Membranes in the Wood of Schisandra chinensis
2018
Torus-bearing pit membranes control water movement between tracheary elements of vascular plants, while at the same time they inhibit spread of air embolisms. They are common in gymnosperms but relatively rare in angiosperms. A recent manuscript noted the presence of such membranes in Schisandra chinensis, a species of basal angiosperm. Building on this prior report, the present manuscript presents evidence for the presence of this membrane in four more species of the genus. The torus-bearing pit membranes are best developed between tracheids, a cell type that acts as a subsidiary conducting system to the vessel members. Detailed observations with an atomic force microscope show the torus to be deposited after formation of the subtending margo is complete.
Scanning electron microscopy of the internal ultrastructure of plant cuticle
Methods for visualizing the intracuticular ultrastructure of plant cuticle by scanning electron microscopy are reported for the (irst time. CUl or fractured edges of macerated Agave and Chvia leaf cuticular membranes have a more or less coarsely reticulate, polylamcllate cuticle proper overlying a finely reticulate cuticular layer. Although these layers have been identified previously by transmission electron microscopy, their ultrastructure can in several respects be visualized more clearly by scanning dectron microscopy (SEM). In particular it is shown that the cuticular layer of Clivia and possibly in Agavt' includes a lamellar (rather than a fibrillar) reticulum and also that apparent pores occur in the cuticular layer. ~l he anaslOmosing and imcrsecting lamellae of the cutic ular layer reticulum form polygons of varying shapes and sizes. 1 he lamell.ac arc apparcntly composed partly of carbohydrate, and each polygonal 'unit' is lilled in vivo with cutin. Differences in ultra-architcc· ture between Agavt' and Glivia renect a suite of characters of utility in plant taxonomy thai can now be accessed morc easily through SEM tech niques than by TElYl.
Simulated diagenesis of plant cuticles — implications for organic fossilisation
Journal of Analytical and Applied Pyrolysis, 2001
The possible origin of the characteristic compositions of pyrolysates of organic fossil leaf cuticles has been investigated by heat treatment of cuticles of recent Kalanchoe grandiflora followed by flash pyrolysis-gas chromatography. Dewaxed cuticles, whether heat-treated or not, yield mainly cyclic compounds from adventitious cell-wall material together with cutin monomers. The pyrolysate of waxy cuticle includes the same compounds but is dominated by wax components which are simply desorbed unchanged under the conditions of pyrolysis. However prior heat treatment of waxy cuticle transforms the pyrolysate so that its chromatogram shows a prominent series of alkene-alkane peaks from C 8 to C 34 , typical of fossil leaf cuticles. It is concluded that leaf waxes, instead of or in addition to cutan, are a principal source of the aliphatic constituents of organic fossil leaf cuticles.