| الوصف: |
Wheat's wide-ranging distribution, in addition to its vast levels of production and consumption make it an essential component of global food security. Ever-increasing population sizes necessitate an increase in global wheat yields to match. This thesis aims to contribute to this goal by addressing a broad range of seemingly disparate themes: evolution, recombination and segregation distortion. What unites these themes is their methodological underpinnings - the use of high-density genotyping arrays, which have undergone considerable development in the past decade. The genetic diversity of wheat is limited by bottlenecks that have occurred in its evolutionary history, both through polyploidization and domestication. This limitation presents difficulties for future yield increases, potentially increasing wheat's susceptibility to pathogens. One area of interest is the rate of novel polymorphism formation overtime. The results presented here indicate that this question will be difficult to answer using molecular clock methodology. Another route to increasing wheat yield may be the manipulation of wheat recombination distribution, removing large areas of linkage drag in the central regions of chromosomes. Previous work in barley suggests that an increase in environmental temperature could shift recombination distribution inwards. The results presented here suggest that whilst this might be the case for some chromosomes in wheat, for the majority of chromosomes, recombination distribution is unaffected by changes in temperature. Segregation distortion, a deviation from Mendelian ratios in progeny of a cross, is also investigated here, with a focus on current practices of detection in the literature. My results indicate that many studies have been using inappropriate methods for the detection of segregation distortion. Also presented in this thesis are novel methods and tools for wheat research, such as the AutoCloner gene-cloning pipeline, allowing researchers to efficiently clone large numbers of genes in previously unsequenced varieties. |
