Date of Award

1993

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Bachelor of Applied Sciences Honours

Faculty

Faculty of Science and Technology

First Supervisor

Dr Ian Bennett

Second Supervisor

Dr Pierre Horwitz

Third Supervisor

Dr Adrianne Kinnear

Fourth Supervisor

Lyall Hunt

Abstract

Soil salinity is widespread throughout the world, and human activity is responsible for increases in the area of land affected by salt. Replanting saline areas using salt-tolerant, or halophytic, species is one method of reclaiming this land. This project investigated the possibility of using in vitro methods to select for increased salt tolerance in halophytic plants. By establishing clonal lines of halophytes in culture and screening those clones for cells exhibiting variation in their capacity to tolerate salt, it may be possible to regenerate plants with elevated salt tolerance. Clonal lines of six species of A triplex (saltbushes) were obtained. Two clones each of A. amnicola and A. cinerea, and one clone of A. nummularia were established as shoot cultures. Explants were induced to form multiple shoots or roots in tissue culture, by the addition of 1μM of the cytokinins kinetin or 2iP, or the auxins NAA, IAA or IBA to M&S basal medium. Callus was readily initiated from leaves of A. nummularia, by the use of M&S medium containing 9-18μM NAA or IAA, and 9μM kinetin or 2iP. Suspension cultures of cells from A. nummularia callus were established in M&S medium without gelling agents or hormones. Regeneration of organs from callus was observed infrequently. The medium giving highest rates of organogenesis could not be defined. Shoots were formed on callus cultures on M&S medium containing 9μM NAA and 9μM kinetin; roots were formed on medium containing a variety of hormone concentrations. Under the conditions imposed here, shoot regeneration can take up to four months to become evident. Callus and suspension cultures of A. nummularia were exposed to up to 342mM NaCI. Callus cultures were not affected by the addition of 43mM NaCI, but growth was depressed at higher salt concentrations. Cell density in suspension cultures were lower when NaCI was present in the medium. These results suggest that although Atriplex nummularia plants possess salt tolerance, this is not expressed or not effective at the cellular level.

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