dc.contributor.advisor |
Susan Turner (University of Auckland) |
en |
dc.contributor.advisor |
John Young (Landcare Research) |
en |
dc.contributor.advisor |
Warwick Silvester (Waikato University) |
en |
dc.contributor.author |
Weir, Bevan |
en |
dc.date.accessioned |
2007-04-01T21:59:52Z |
en |
dc.date.available |
2007-04-01T21:59:52Z |
en |
dc.date.issued |
2006 |
en |
dc.identifier.citation |
Thesis (PhD--Biological Sciences)--University of Auckland, 2006. |
en |
dc.identifier.uri |
http://hdl.handle.net/2292/394 |
en |
dc.description.abstract |
This research investigated the rhizobia that are associated with New Zealand legume plants. Rhizobia are a diverse group of bacteria that live in symbiosis with legumes in root nodules. Rhizobia fix Nitrogen from the atmosphere and provide this nutrient to the plant.
The objectives of this research were to: 1) Determine the identity of the rhizobial species nodulating the native legumes of New Zealand: Sophora (kowhai), Carmichaelia (NZ broom), and Clianthus (kakabeak); and the identity and origin of rhizobial species nodulating invasive exotic legumes in New Zealand: Ulex (gorse), Cytisus (broom), and Acacia (wattles). 2) Determine the specificity and nitrogen fixing capacity of both groups of rhizobia. 3) Investigate the possible exchange of transmissible symbiotic
genetic elements. A polyphasic strategy was used to determine the identity of bacterial
isolates. The 16S rRNA, atpD, recA, and glnII genes were PCR amplified and sequenced, then analysed by maximum likelihood and Bayesian methods.
Phenotypic characters were also assessed by use of the Biolog and FAME techniques. Nodulation and fixation ability was assessed by inoculating legume seedlings with rhizobial strains, then determining nitrogenase activity after ten weeks by gas chromatography, and examining roots for nodules.
A gene involved in symbiosis, nodA, was sequenced from rhizobial strains to
determine if transmission between strains had occurred.
The results of the experiments showed that the native legumes were
predominately nodulated by diverse Mesorhizobium spp. that contain three
different nodA genotypes (two of which are novel) that have transferred
between rhizobial strains. The Mesorhizobium spp. showed little nodulation specificity and could nodulate an exotic legume Astragalus (milk vetch), but
not the invasive weed legumes. Rhizobium leguminosarum was also found
to nodulate native legumes, albeit ineffectively. The exotic invasive woody
legumes of this study were nodulated by diverse Bradyrhizobium spp. that
had nodA genotypes typical of Australian and European species.
The origins of these bacteria can not be categorically determined. However
the evidence is presented to suggest that nodulating Mesorhizobium
spp. arrived with the ancestors of the native legumes, while Bradyrhizobium
spp. nodulating Ulex and Cytisus arrived recently from Europe. Bradyrhizobium spp. nodulating Acacia may be recently introduced, possibly from Australia, although further work is required to confirm these hypotheses. |
en |
dc.description.sponsorship |
This study was supported by a grant from the Marsden Fund of the Royal Society of New Zealand, under contract 97-LAN-LFS-002, and a grant from the Non-Specific Output Fund of Landcare Research. |
en |
dc.language.iso |
en |
en |
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
PhD Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA1707492 |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
en |
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.subject |
rhizobia |
en |
dc.subject |
native legumes |
en |
dc.subject |
microbiology |
en |
dc.subject |
mesorhizobium |
en |
dc.subject |
bradyrhizobium |
en |
dc.subject |
kowhai |
en |
dc.subject |
sophora |
en |
dc.subject |
rhizobium |
en |
dc.title |
Systematics, Specificity, and Ecology of New Zealand Rhizobia |
en |
dc.type |
Thesis |
en |
thesis.degree.discipline |
Biological Sciences |
en |
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Doctoral |
en |
thesis.degree.name |
PhD |
en |
dc.subject.marsden |
Fields of Research::270000 Biological Sciences::270400 Botany |
en |
dc.rights.holder |
Copyright: The author |
en |
pubs.local.anzsrc |
06 - Biological Sciences |
en |
pubs.org-id |
Faculty of Science |
en |
dc.identifier.wikidata |
Q111963925 |
|