Science Collected Works - Theses

Permanent URI for this collection

http://hdl.handle.net/11343/304

Filters

2004 - 2009 2
1 1
Reset filters

Settings
Statistics
Citations
Subject: Eucalyptus × Type: PhD thesis ×

Search Results

Now showing 1 - 2 of 2
  • Item
    Thumbnail Image
    A phylogenetic analysis of the bloodwood eucalypts (Myrtaeae)
    Osorio, Carlos Alberto Parra (University of Melbourne, 2009)
  • Item
    No Preview Available
    Molecular and physiological studies of salt tolerance in eucalypts
    Faridah, Eny (University of Melbourne, 2004)
    Effects of salinity on plant growth have been investigated in numerous studies looking at morphological, physiological and molecular aspects. In trees, and in eucalypts in particular, current knowledge is limited to the first two aspects. This stands in contrast to their important role in rehabilitation programs of salt-affected areas. This thesis made use of E. camaldulensis x E. globulus hybrid clones of known salt tolerance to investigate different molecular mechanisms utilized by these plants in response to salt stress. Effects of salinity on plant physiology and molecular biology were assessed after exposing clones to varying salt (NaCI) concentrations for different periods of time in a hydroponic experiment. EcgNaH, a gene fragment with homology to vacuolar Na+/H+ antiporter genes which, when overexpressed, is known to confer salt tolerance in many plant species, was identified and isolated from this hybrid. Also, fragments of genes known to be involved in nutrient uptake were identified and isolated, with particular focus on EcgPT, encoding a Phosphate Transporter. Expression studies using Northern-Blot analysis revealed that EcgNaH was upregulated in the presence of salt in an organ-specific manner, and increased over time when plants continued to be exposed to salt. EcgNaH was differently expressed in different clones, indicating, in combination with growth data, different levels of salt tolerance. Also the expression of EcgPT was found to be affected by salt suggesting a direct effect of salinity on phosphate uptake. EcgPT expression was regulated in an organ-specific way, and a time course analysis showed that EcgPT was increasingly upregulated after longer exposure to salt, but reaching a peak after three weeks of exposure indicating the plant's adaptation to the lower P status caused by salinity. EcgPT was expressed differently in different clones indicating different degrees of phosphate transporter activation in order to tolerate salt stress. Molecular data are discussed in relation to growth data and measurements of ion levels in different organs of different clones and under various salt regimes during the course of the hydroponic experiment.