Studies on the cellular and molecular basis of salt resistance in a halotolerant Arabidopsis thaliana cell line

El-Sheikh, Medhat (2002) Studies on the cellular and molecular basis of salt resistance in a halotolerant Arabidopsis thaliana cell line. PhD thesis, University of Glasgow.

Abstract

Global agricultural output is now severely affected by salinity due in part to the cultivation of primary salinated land, and partly through irrigation with brackish water. Unfortunately, the major crop species are all salt sensitive (glycophytes) and do not perform well in even mildly saline soils. Consequently there is now much attention focussed on developing new crops that are more salt resistant. Progress in this area has been hampered because the model plant, Arabodopsis thaliana, is also a glycophyte that will not complete a full life cycle in a one-fifth dilution of sea water. However, at the University of Glasgow a halotolerant cell suspension (HHS) line has been developed from a wild type (WT) Arabidopsis culture that grows well in three-quarter strength seawater. The work presented in this thesis was directed towards understanding better how the HHS cope with high salinity. The morphology of the two cell lines were examined at the fine and untrastructural level. The HHS, and indeed all halotolerant cells lines studied to date, contain an extensive array of small vacuoles and vesicles (SV-V) in their cytoplasm, as well as a large central vacuole; this is not observed in WT cells. It is feasible that the SV-V are involved in the rapid sequestration of toxic ions away from the cytoplasm. There was some evidence for endocytosis and exocytosis but further clarification of the dynamics of SV-V movement is required. There is also some indirect evidence that ABC transporters may be associated with the SV-V. Attempts were made to clone the first plant Na+ transporters from plants using genome sequence data to design PCR primers and RT-PCR on message prepared from the HHS cells. Initaially, six putative Na+ / H+ antiporters were identified but no PCR products could be generated from three of these. Of the remaining three, two have subsequently been shown to code for genuine Na+ / H+ antiporters (AtNHX1 and AtSOS1), and the other may be a new transporter that has not been characterized yet (AtT12H17.230). In addition, Differential Display-PCR was used to identify some of the differentially abundant transcripts in WT and HHS cells. Unfortunately, due to a severe fire, this work was not completed. However, the method does work but now Arabisopsis DNA chips are routinely available, microatxaying appears to be a better approach.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: Dr. Peter Dominy.
• Keywords: Plant sciences.
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: Supervisor, not known
• Date of Award: 2002
• Depositing User: Enlighten Team
• Unique ID: glathesis:2002-71411
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 May 2019 10:49
• Last Modified: 26 May 2021 09:19
• URI: https://theses.gla.ac.uk/id/eprint/71411