Title page for ETD etd-11072012-133714


Document Type Master's Dissertation
Author Stewart, Annie Cecilia
Email angels@aspirata.co.za
URN etd-11072012-133714
Document Title Bacterial endophytes associated with Eucalyptus nitens clones
Degree MSc
Department Microbiology and Plant Pathology
Supervisor
Advisor Name Title
Prof T A Coutinho Co-Supervisor
Prof S N Venter Supervisor
Keywords
  • Eucalyptus nitens clones
Date 2012-09-07
Availability unrestricted
Abstract
Plants are colonised by a vast amount of bacteria which are found in parts such as seeds, roots, leaves and fruits while fewer are found on blossoms, stems and vascular tissue. These different parts of plants make up distinct micro ecosystems which may result in different bacterial species (endophytes) colonizing these ecosystems. Such interactions could be for life or only a short period of time and may cause no significant damage or they could be latent pathogens. Isolations of both Gram negative and Gram positive bacteria have been made from an extensive range of plant species and include bacterial genera from the following groups: Firmicutes, Actinobacteria, Proteobacteria, Proteobacteria, and Proteobacteria. The focus of this study was the endophytic bacterial community of resistant, healthy and diseased Eucalyptus nitens clones, the latter of which showed symptoms of bacterial blight and die back previously described as caused by Pantoea ananatis. The endophytic bacteria of these sampled clones were studied using culturing dependent and independent methods. The focus was on the Enterobacteriaceae in order to determine whether P.ananatis is present as an endophyte of these clones. To obtain the isolates, standard culturing techniques were used, followed by sequence identification of the 16S rRNA as well as two housekeeping genes, rpoB and gyrB. Results obtained from the culturing study were compared to results obtained from a PCR-DGGE study of the same samples. Although no conclusion could be drawn as to which organism present caused the disease symptoms on the susceptible clones, it was seen that Enterobacter and Pantoea, were the most frequently isolated in both of the studies from all clones sampled. This implies that they are present as endophytes in the E.nitens clones, together with Pseudomonas and Bacillus as suggested by the DGGE study.

Copyright 2011, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria

Please cite as follows:

Stewart, AC 2011, Bacterial endophytes associated with Eucalyptus nitens clones, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11072012-133714 / >

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