Diversity of root nodulating bacteria associated with Cyclopia species

Show simple item record

dc.contributor.advisor Steyn, P.L. en
dc.contributor.postgraduate Kock, Martha Magdalena
dc.date.accessioned 2013-09-06T17:41:07Z
dc.date.available 2005-05-19 en
dc.date.available 2013-09-06T17:41:07Z
dc.date.created 2004-04-24 en
dc.date.issued 2006-05-19 en
dc.date.submitted 2005-05-09 en
dc.description Thesis (PhD(Microbiology))--University of Pretoria, 2006. en
dc.description.abstract In recent years, the rhizobial taxonomy changed significantly with the discovery of novel symbiotic associations between legumes and nodulating bacteria. This was aided by the focus shift from studying only agricultural crops to legumes indigenous to certain regions, ultimately to discover new inoculant strains and to uncover the secrets of the rhizobium¬legume symbiosis. In previous studies on the diversity of South African rhizobia, it has become clear that our country has a wealth of rhizobia. Cyclopia is a legume genus, which belongs to the fynbos biome of South Africa. Honeybush tea is a herbal infusion manufactured from the leaves and stems of certain Cyclopia spp. Commercial cultivation of this potentially new agricultural crop is now developed to protect the natural Cyclopia spp. populations from harvesting and ultimately extinction. Superior inoculant strains are necessary for these commercial seedlings. The diversity of root-nodulating strains isolated from 14 Cyclopia spp. was determined using 16S-23S IGS-RFLP and partial 16S rDNA base sequencing. Based on 16S-23S IGS-RFLP and partial 16S rDNA base sequencing most of the isolates, with the exception of seven strains, were found to belong to the genus Burkholderia. More extensive phylogenetic, symbiotic and phenotypic studies of selected strains were performed using near full-length 168 rDNA base sequencing, nodA base sequencing and substrate utilisation analysis. In the genus Burkholderia, the isolates belonged to the novel root-nodulating species Burkholderia tuberum and several novel, undescribed Burkholderia genotypes. However, no new Burkholderia species could formally be proposed, since DNA-DNA hybridisation analysis, which is a prerequisite for the description of new species could not be performed in our laboratory. The seven strains not affiliated with the Burkholderia genus belonged to two Bradyrhizobium genospecies, R tropici and a possibly new genus in the a-Proteobacteria. The nodA sequences of all the Cyclopia isolates corresponded to a large extent, indicating that different chromosomal genotypes harbour the same symbiotic genotype. All the isolates of the Cyclopia genus appear to be acid-tolerant, which is in agreement with the acidic nature of the soil from which the strains were isolated. en
dc.description.availability unrestricted en
dc.description.department Microbiology and Plant Pathology en
dc.identifier.citation Kock, MM 2004, Diversity of root nodulating bacteria associated with Cyclopia species, PhD thesis University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/24489 > en
dc.identifier.other H577/ag en
dc.identifier.upetdurl http://upetd.up.ac.za/thesis/available/etd-05092005-161834/ en
dc.identifier.uri http://hdl.handle.net/2263/24489
dc.language.iso en
dc.publisher University of Pretoria en_ZA
dc.rights © 2004, 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. en
dc.subject Root tubercles en
dc.subject Symbiosis en
dc.subject Legumes roots en
dc.subject Rhizobacteria en
dc.subject Rhizobium en
dc.subject UCTD en_US
dc.title Diversity of root nodulating bacteria associated with Cyclopia species en
dc.type Thesis en


Files in this item

This item appears in the following Collection(s)

Show simple item record