Luisa Carraro

Tapetal Ultrastructural Changes During Pollen Development. III. Studies on Gentiana Acaulis

SUMMARYIn Gentiana acaulis, where the anthers are elongated and mature in a scalar way. the tapetal cells are intermingled with pollen grains and possess simultaneously spherical cytoplasmic bodies, sporopollenin bodies (« orbicular bodies ») and grey bodies. The contemporaneous presence of such bodies is probably related to the fact that the cell walls of the tapetal cells disappear and therefore they can migrate towards anther zones which are already mature.

Tapetal Ultrastructural Changes During Pollen Development. I. Studies on Antirrhinum Maius

SUMMARYAnther sections of Antirrhinum maius in various stages of development have been examined with the electron microscope and the ultrastructural modifications of the tapetal cells have been followed during the development of the pollen grains. Characteristic of the early stages of development is the presence of a great number of intensely proliferating Golgi bodies and of spherical bodies, located in the perinuclear space in proximity of the plasmalemma and in the endoplasmic reticulum. They are bounded by a single membrane on which ribosomes are regularly ranged facing the body cavity. Probably the bodies located in the perinuclear space play a role in the nuclear-cytoplasmic information exchanges, while those in connection with the endoplasmic reticulum seem to be simply related to an enhanced endoplasmic reticulum activity. In the late tetrad stage a second body population appears. These bodies are spherical, electrondense and without bounding membrane. They are located at the cell periphery toward...

Peroxidase Activity and Gametophytic Incompatibility: Bud-Pollination in Petunia Hybrida

SUMMARYThe presence and distribution of peroxidase activity has been examined in non-, self- and cross-pollinated bud styles, in relation to the well-known bud pseudo-self-compatibility. No peroxidase activity is present in the apoplastic space of non-pollinated and cross-pollinated young styles. Self-pollination causes the appearance of peroxidase activity in the apoplastic space of the transmitting tissue region where the pollen tubes elongated, indicating that bud pistils are able to recognize «incompatible» pollen tubes and to react to their growth. A similar interaction between pollen tubes and transmitting tissue cells was observed in cross- and self-pollinated pistils regarding the utilization of cellular reserves. Bud pseudo-self-compatibility is explained by the lack in non-pollinated bud styles of the apoplastic peroxidase activity observed in adult non-pollinated pistils. A key role is proposed for the apoplastic peroxidase activity present in non-pollinated styles in the incompatibility reacti...

Tapetal Ultrastructural Changes During Pollen Development. II. Studies on Pelargonium Zonale and Kalanchoë Obtusa

SUMMARYThe ultrastructure of the tapetal cells was studied in Kalanchoe obtusa and Pelargonium zonale. In an early stage of development the most characteristic feature was the presence of many spherical bodies bounded by a single membrane and containing cytoplasmic material. These bodies were localized in dilations of the ER and in the perinuclear space. In later stages, when the pollen was mature, the tapetal cells of Pelargonium contained many « grey » bodies and their plasmalemma was in close connection with the sculptures of the pollen grains.

Leaf morphology and carbon isotope discrimination in members of the genus Salsola. I. Studies on Salsola kali L.

SUMMARYThis paper refers to morphological and physiological studies on Salsola kali L. leaves of various age; 13C/12C ratio was measured and anatomical and ultrastructural aspects related to their C4 photosynthesis were analyzed by means of light and electron microscopy. Interesting results have been attained regarding chloroplasts, plasmodesmata and vesicles proliferation, probably connected with the C4 metabolism.

Electron-Cytochemical Localization of Peroxidase in Self- and Cross-Pollinated Styles of Primula Acaulis

SUMMARYPrimula acaulis is characterized by an heteromorphic incompatibility. Through electron microscopic techniques, based on the DAB cytochemical reaction, it has been possible to detect the presence of peroxidase in the intercellular spaces and in the cell walls of the stylar transmitting tissue. Peroxidase has been observed only in self-pollinated styles, that is after ilegitemate crosses. This fact suggests that peroxidase may be linked with incompatibility responses.

Microsporogenesis of the feathers (fertile branches derived from annual buds) in Vitis vinifera, cv Picolit giallo

Abstract Using light and electron microscopy, we have studied the microsporogenesis and tapetal development of the feathers in two different low producing clones of Picolit giallo (sp. Vitis vinifera). In these clones while the productivity of the main branches (fertile branches originated from buds, formed in the previous year, that remained silent during the winter) is very low, that of the feathers (fertile branches derived from annual buds) is always normal. The microsporogenesis and tapetal development proceed normally in almost all the examined anthers; it is remarkable that at the tetrad stage the tapetal cells appear well structured without any degeneration symptom, unlike what observed for the main branches. Moreover in most of the mature anthers the pollen grains are numerous, pleinty of organelles and show sometimes thickenings in the callose layer under their wall. The tapetal cells of these anthers have disappeared. Only in few anthers we observed the presence of collapsed pollen grains and t...

Stylar peroxidases and heteromorphic incompatibility reactions in Primula acaulis Hill («thrum» morph)

SUMMARYIn non-, self- and cross-pollinated styles of Primula acaulis «thrum» morph, the distribution of apoplastic peroxidase activity has been investigated, by means of the cytochemical treatment with diaminobenzidine. Apoplastic peroxidase activity was detected throughout the transmitting tract (at the «neck» region level) in non- and self-pollinated styles. The enzyme has been related to the predisposition of incompatible pollen tube rejection, no appreciable differences in enzyme distribution having been found between non- and self-pollinated styles since, in this morph, incompatible pollen tubes hardly ever reach the stylar neck. Compatible intermorph pollination caused the disappearance of apoplastic peroxidase activity in the central portion of the transmitting tract, where pollen tubes elongated, utilizing the reserves of the stylar cells, which appeared highly degenerate. Stylar apoplastic peroxidases seem then to play a role in heteromorphic incompatibility responses.

Cytochemical Localization of Diamine Oxidase in Helianthus tuberosus Developing Tubers

Summary The localization of diamine oxidase (DAO, EC 1.4.3.6) activity was investigated in tubers of Helianthus tuberosus by using an electron microscopy method based on the direct cytochemical detection of DAO-generated hydrogen peroxide by reaction with cerous ions (CeCl 3 ). During tuber formation no detectable precipitate was found in samples collected in September and October while an electron-dense granular precipitate appeared in the cell walls, but not in organelles, in samples collected in November 3 reaching the maximum on 19. The trend of DAO activity, measured by the radiometric method based on the recovery of 14 C-pyrroline derived from putrescine oxidation, did not parellel the cytochemical pattern as it showed high activity in September followed by a decrease in November. Since total DAO activity does not necessarily reflect any single particulate one, we infer that the biochemical trend is determined by an organellar activity which is not detectable cytochemically. The hypothesis that during tuber development apoplastic and symplastic DAO activities play two different roles and are differently regulated in the cell is discussed.

An electrophoretic approach to Basidiomycetes taxonomy: Intraspecific variability, varieties, ecological influences

Abstract Basidiospores of several Basidiomycetes species were treated with electrophoretic techniques, comparing the different protein fractions of the soluble component of the spores wall. The electrophoretic data were elaborated to obtain dendrograms indicating the similarity degree. The method was set up and tested for its validity. The technique showed that the degree of variability within the observed species escaped any generalization, covering a broad range; it was possible to identify the varieties in dendrograms of species grown in the same/different geographical zones; the growing environment and the symbiotic host often influenced the electrophoretic pattern of the spore wall proteins and resulted in dendrograms reflecting the ecological conditions. Abbreviations: ACP, acid phosphatases; EST, esterases; UPGMA, unweighed pair‐group method using arithmetical average