Spatial Relation of Stem Hydroids to Branch Hydroids in Four Pleurocarpous Mosses

The anatomy of branch and main stem connections, with respect to the spatial relation of central strands, was studied in four species of pleurocarpous mosses: Climacium americanum, Climacium dendroides, Rhytidiadelphus triquetrus, and Rhytidium rugosum. In each of these species the central strand consisted entirely of hydroids. Fresh specimens obtained in Iowa and Wisconsin were fixed in CRAF III. To soften tough cell walls, samples were soaked in concentrated (50% aqueous) hydrofluoric acid for one week prior to dehydration in ethyl alcohol. Paraffin (61°c mp) was used as the embedding medium. In the several branch connections studied for each species there was no direct connection between stem and branch central strands

Desarrollo de tejido vascular en etapas precoces de combinaciones de injerto/patrón de diferente compatibilidad

Comunicación presentada en el X Congreso Nacional de Ciencias Hortícolas (Pontevedra, mayo de 2003), en su apartado "Fruticultura".El objetivo de este trabajo fue encontrar diferencias tempranas de compatibilidad en el desarrollo de uniones entre yemas del cultivar Moniquí de albaricoquero injertadas en plantas híbridas provenientes de cruzamientos interespecíficos entre albaricoquero y ciruelo Mirobolán.Peer reviewe

Alternate Modes of Photosynthate Transport in the Alternating Generations of Physcomitrella patens

abstract: Physcomitrella patens has emerged as a model moss system to investigate the evolution of various plant characters in early land plant lineages. Yet, there is merely a disparate body of ultrastructural and physiological evidence from other mosses to draw inferences about the modes of photosynthate transport in the alternating generations of Physcomitrella. We performed a series of ultrastructural, fluorescent tracing, physiological, and immunohistochemical experiments to elucidate a coherent model of photosynthate transport in this moss. Our ultrastructural observations revealed that Physcomitrella is an endohydric moss with water-conducting and putative food-conducting cells in the gametophytic stem and leaves. Movement of fluorescent tracer 5(6)-carboxyfluorescein diacetate revealed that the mode of transport in the gametophytic generation is symplasmic and is mediated by plasmodesmata, while there is a diffusion barrier composed of transfer cells that separates the photoautotrophic gametophyte from the nutritionally dependent heterotrophic sporophyte. We posited that, analogous to what is found in apoplasmically phloem loading higher plants, the primary photosynthate sucrose, is actively imported into the transfer cells by sucrose/H[superscript +] symporters (SUTs) that are, in turn, powered by P-type ATPases, and that the transfer cells harbor an ATP-conserving Sucrose Synthase (SUS) pathway. Supporting our hypothesis was the finding that a protonophore (2,4-dinitrophenol) and a SUT-specific inhibitor (diethyl pyrocarbonate) reduced the uptake of radiolabeled sucrose into the sporangia. In situ immunolocalization of P-type ATPase, Sucrose Synthase, and Proton Pyrophosphatase – all key components of the SUS pathway – showed that these proteins were prominently localized in the transfer cells, providing further evidence consistent with our argument.View the article as published at https://www.frontiersin.org/articles/10.3389/fpls.2017.01956/ful

Localization of peroxidase enzyme in the bark of Hevea brasiliensis and its implication in anatomy

Localization of peroxidase enzyme with respect to seasons has been carried out in the bark of mature trees of Hevea brasiliensis using guaiacol and hydrogen peroxide as the substrate. Cell walls of sieve tubes including sieve plates, and cytoplasm of phloic rays both in the soft and hard region of the bark showed positive indication of peroxidase activity with reddish brown coloration. Sieve tubes differentiated recently from the derivatives of cambium also stained deeply. The cell wall of the phloic rays remained passive for peroxidase activity but the cytoplasm appeared to be granulated and was in a state of streaming motion which was evident in cross sectional view of the bark. Companion cells did not give any indication of peroxidase activity but it was localized in the intercellular spaces of axial parenchyma cells in the soft bark. Phloic rays exhibited seasonal variation for peroxidase enzyme while the activity was localized throughout the year in the sieve tubes. In the samples taken during December- January, phloic rays were unstained throughout the bark. Bark samples collected in the month of March and April showed deep coloration for phloic rays extending from the phellogen to the periphery of the cambial zone. In the month of June, the partially differentiated phloic rays in the cambial zone stained for peroxidase and subsequently differentiated ones were completely unstained. The phloic rays in the months of September and October remain unstained in the soft bark while it gave a brown coloration in the hard bark region

Cyanogenesis and the onset of tapping panel dryness in rubber tree.

O objetivo deste trabalho foi estudar a influência da cianogênese no estabelecimento do secamento do painel de sangria (TPD) e os aspectos fisiológicos e histológicos do floema secundário do tronco (painel de sangria) em seringueira (Hevea spp.)