Doctoral Thesis
Functional characterisation of orthologues of an anti-frost gene of wheat
Doctor of Philosophy (PhD), Murdoch University
2024
Abstract
Wheat (Triticum aestivum L.) is a global cereal crop, with rising demand as the world population grows. Australia, particularly Western Australia, is a leading wheat producer. However, frost is a major challenge, causing national losses estimated at AUD 400 million annually. The Australian wheat crop, which is rain-fed, is sown in autumn, and is vulnerable to damage from frost events during early reproductive and grain-filling stages from late August to early October. There are no Australian wheat cultivars which are tolerant to frost events during the critical early reproductive stages and existing frost mitigation strategies result in decreased yields because the growing season is shortened (different sowing dates, shorter season varieties, avoiding sowing in frost-prone areas). One approach, reducing ice-nucleating bacteria through chemical spraying, is impractical because it is difficult to predict frost events in advance.
Novel genes encoding Ice Recrystallisation Inhibition Proteins (IRIPs) may provide an alternative genetic solution for improving frost tolerance in wheat. When expressed in other plants, IRIPs have improved tolerance to frost treatments. In the present investigation, a 4AIRIP gene present in T. aestivum L. was identified, and characterised. Conserved domains and special features of the IRIP were identified. The 4A-IRIP possesses ice-binding surfaces. Differential expression of genes considered as IRIPs, and other cold-responsive genes, were analysed through the growth cycle of wheat plants after cold treatment. The expression of cold-related genes varied in different tissues of wheat plants: most of the genes studied were upregulated at vegetative stages but exhibited reduced expression in reproductive tissues. The responses of elite wheat cultivars to tissue culture and regeneration were also studied, and a rapid mature-embryo-derived wheat regeneration protocol was developed. Using Agrobacterium-mediated transformation to introduce an IRIP gene, transformation efficiencies of 6-10.5% were achieved. The transgenic nature of selected lines was confirmed using colourimetric and PCR assays for the selectable gene used (phosphinothricin N-acetyltransferase – PAT). Time and facility access did not allow the transgenic plants generated to be challenged for simulated frost responses; this aspect is the subject of a subsequent project.
Details
- Title
- Functional characterisation of orthologues of an anti-frost gene of wheat
- Authors/Creators
- Hennadige Sandali Ithsitha Fernando
- Contributors
- Michael G. K. Jones (Supervisor) - Murdoch University, Centre for Crop and Food InnovationJohn Fosu-Nyarko (Supervisor) - Murdoch University, Centre for Crop and Food Innovation
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005748928607891
- Murdoch Affiliation
- Centre for Crop and Food Innovation; State Agricultural Biotechnology Centre
- Resource Type
- Doctoral Thesis
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