Crop breeding is an endeavour which began over ten thousand years ago. Initially new variants would have been found by chance in the wild or selected from cultivated fields where uncontrolled crossing may have occurred. Over time, controlled crossing procedures have been developed for almost all crops leading to major improvements in performance. Choice of parents and selection of progeny has now become a precise art with the advent of genomic technologies and refined phenotyping. However,a major restriction remains in the number of generations required for stable varieties to be created by normal segregation from the heterozygous offspring of the initial crosses. Two artificial techniques may avoid the need for repeated selfing or back-crosses. Double haploid (DH) techniques manipulate gamete development to regenerate fully homozygous plants in a single generation, while genetic modification (GM) introduces desirable genes directly without the need for crossing. Both DH and GM are valuable tools for crop researchers investigating gene function and carrying out trait dissection as well as for breeders creating new varieties directly. However, both are reliant on efficient tissue culture methods. Oat is a significant crop, approaching 1M tonnes of production annually in the UK, with an increasing demand for high quality milling varieties whose breeding must keep pace with that of competing crops. Oat has proved recalcitrant to tissue culture and efficient protocols are lacking for both DH and GM. The aim of this project was to address this lack. Media optimisation steps improving DH efficiency are reported.F2 progeny of a cross between responsive and non-responsive parents were analysed with flow cytometry and SSR markers to confirm that haploids and spontaneous dihaploids were produced by the method. Analysis of donor plant phenotypic traits and tissue culture response suggest ways to further optimise the DH protocol to reduce labour and increase efficiency. Attempts to transform oat were not successful, however improvements in regeneration efficiency will support further optimisation of the transformation procedure. Overcoming oat recalcitrance to tissue culture methods is an incremental process. The improvements described here provide a reliable baseline from which to test further modifications.
- Avena sativa, Double haploid, GM, Tissue culture
Thesis, 5.19 MB, PDF
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Thesis, 5.19 MB, PDF
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