archives@tulane.edu / 1 / Peter Tellez

ABSTRACT A comparative morphological study on the leaf of Melastomataceae was made for 21 species of 11 genera in Taiwan. The morphological characters studied include leaf venation, trichome, epidermal cell, anticlinal wall, stomatal type and crystal type. The results are given as follows. Two types of venation are recognized, i.e. pinnate and palmate venations. The leaves of all species showed their palmate venation except for those of Memecylon lanceolatum. Seven types of trichrome could be observed in the studied species, which consist of peltate scales, bladder-like glandular hairs, multiseriate unbranched hairs, multiseriate unbranched glandular hairs, short-stalked glandular hairs, armed hairs and stellate with glandular hairs. All of species have short-stalked glandular hairs occurred on the leaves of all species except Memecylon lanceolatum which has no trichrome at all. In addition, bladder-like glandular hairs on upper epidermis of leaves in Medillia and on both epidermis of leaves in Blastus. The epidermal cells of the leaf surfaces are polygonal or irregular in shapes, and the anticlinal walls are straight, arched, repand and sinuous. There are five types of stomata, which are composed of anomocytic type, diacytic type, paracytic type, polocytic type and staurocytic type. Only Melastoma kudoi and Osbeckia chinensis have stomata at upper epidermis. Two kinds of crytals appeared, i. e. styloids and druses. However, the occurrence of crystal is unstable specifically and generically, which implies that it is invaluable for specific and generic delineation. Additionally, druses could be found epiphytic on multiseriate unbranched hairs of the genera Melastoma and Osbeckia. According to this study, the features of leaf venation, trichrome, epidermis cell, anticlinal wall and stomatal type could provide evidence for taxonomy of this family.

No description available.

The birch leaf-mining sawfly, Fenusa pusilla (Lep.), has been a major pest of birch trees in Canada since its introduction into North America in 1923 (Britton, 1924a, 1924b). From that date onwards, serious infestations of leaves of most species of birch have been reported, particularly from the maritime provinces. The species was first noted in the province of Quebec in 1929 by Dr. Lionel Daviault of Quebec City (Daviault, 1937) who observed it developing on seven birch species at Berthier. [...]

No description available.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references (p.48-50).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1943. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 41-42).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The role of cytoplasmic pH in guard cell signal transduction was investigated in epidermal strips of Commelina communis. The cytoplasmic pH of guard cells was measured by dual excitation ratio confocal laser scanning microscopy. Large transient alkalinisations occurred for up to 20 minutes both during closure, in response to ABA and calcium, and opening in response to IAA and fusicoccin. Therefore the direction of the pH change does not determine the direction stomatal movement in Commelina communis in contrast to previous reports in Paphiopedilum tonsum. Furthermore, CO₂ caused a slow acidification during stomatal closure, indicating that pore movements are not always associated with a transient cytoplasmic alkalinisation. The internal pH of guard cells was buffered by low concentrations of isobutyrate. Small reductions in stomatal closure in response to ABA and calcium were observed, however, responses to CO₂, IAA and fusicoccin were unaltered. High levels of isobutyrate stimulated wide stomatal opening for all stimuli. Therefore manipulation of cytoplasmic pH only give limited support in the case of ABA and calcium that cytoplasmic pH changes are either necessary for or modulate stomatal movements. The observed pH changes may therefore be a consequence of the mechanism underlying pore movement rather than genuine cytoplasmic signals per se, A model is described based on strong ion and weak acid chemistry which predicts that the observed pH transients result from changes in the concentrations of chloride and malate which charge balance the potassium fluxes during stomatal movements. No suitable fluorescent indicator was found to measure pH in either the apoplast or vacuole. However the volume of the guard cell lumen, vacuole, nucleus and chloroplast were directly measured during stomatal movements and the cytoplasmic volume was calculated. These volumes were used to re-calculate compartmental pH and ion concentrations from previous reports.

Plantations of Eucalyptus spp. are expanding world-wide to serve growing global requirements for timber and pulp products. Together with this expansion, there has been a concomitant increase in diseases affecting these trees. Most of these are caused by fungi but there are a growing number of diseases caused by bacterial pathogens. Very little is known about them and the focus of this study was to consider species in the genus Pantoea and their association with diseases on Eucalyptus. Pantoea spp. are known pathogens of agricultural crops in South Africa and elsewhere in the world. They are also ubiquitous occurring in diverse ecological niches. Despite their prevalence, little is known about their association with plants, particularly where they occur as pathogens. The first chapter of this thesis presents an overview of the important aspects concerning the identification and classification of bacterial pathogens. Different techniques used for bacterial identification and classification were considered. These techniques are classified into different levels, based on their complexity and level of data resolution. As techniques have developed and been refined, our understanding of how organisms are related to each other has increased. An overview of the taxonomic history of the genus Pantoea was used to illustrate this point. An interaction between two Pantoea spp. and Colletogloeopsis zuluense, a serious fungal pathogen of Eucalyptus has been reported in the past. In the second chapter of this thesis, I considered the view that pathogenicity of C. zuluense is enhanced when infection occurs in conjunction with the two Pantoea spp. The identities of the two Pantoea spp. were confirmed as Pantoea ananatis and Pantoea stewartii subsp. indologenes. Both greenhouse and field inoculation trials with the two Pantoea spp. and C. zuluense failed to confirm that there is an increase in pathogenicity of C. zuluense when these bacteria are present. Studies in chapter three of this thesis, considered the identity of bacteria associated with diseased Eucalyptus leaf material from Uganda, Thailand and Uruguay. Symptoms observed in these countries were very similar and they were also similar to those of bacterial blight observed in South Africa. The majority of isolates obtained from Thailand were identified as Pantoea dispersa, based on both phenotypic and DNA-based data. This is the first report of Pantoea dispersa associated with disease on Eucalyptus. Uganda isolates were identified as Pantoea vagens prov.nom., a new species in the genus Pantoea. The majority of Uruguay isolates were identified as either Pantoea ananatis or Pantoea vagens prov.nom. The remaining isolates from Uruguay were found to belong to Pantoea eucalyptii prov.nom., a proposed new Pantoea sp., as well as Pantoea agglomerans. Pathogenicity results showed that the majority of isolates from all three countries were moderately pathogenic, eliciting moderate reactions in both tobacco and susceptible Eucalyptus grandis x nitens hybrid clones. Overall, results of studies presented in this thesis showed that Pantoea spp. can exist in complex interactions with both plants and fungi. These interactions are, however, not necessary for bacterial survival. We believe that the majority of Pantoea spp. are opportunistic pathogens based on their ability to selectively enter into interactions as well as occur epiphytically on plants. Variability in pathogenicity, both observed in this study and previously reported, further supports this view. Additional studies are needed to determine the conditions conducive to disease development in order to fully understand the threat these pathogens pose to global forestry. / Dissertation (MSc (Microbiology))--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted