Developing tools for introgression into wheat where recombination is not possible

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This project will address an important problem which has hampered the exploitation of the genetic diversity held within wild relatives of wheat. Being able to work with wild relatives so that beneficial characteristics can be introduced into wheat will be a major scientific achievement and dramatically improve the way breeders can generate new varieties of wheat with increased performance. Some wild relatives are adapted to thrive under different climatic conditions to that of domestic wheat, or they carry natural resistance to important diseases and/or carry other important characteristics which could influence yield. What we want to do is to produce the tools which will allow the exploitation of this diversity and genetically introduce these favourable characteristics into wheat. In doing so we will be enable wheat breeders to, amongst other things, improve wheat performance in a sustainable way, increase yield, introduce disease resistance and drought tolerance. In a small number of cases this has already been achieved. What stops other wild relatives being used? The reason is that similarity of gene order, particularly at the chromosome ends (telomeres), is necessary to allow the chromosomes to align efficiently and recombine during the process of meiosis. Without recombination there isn't the opportunity to introduce the genetic diversity of wild relatives into wheat. Recombination Is possible in some cases but many wild relatives have rearranged their chromosomes compared with wheat chromosomes, making gene transfer difficult, if not impossible, by recombination during meiosis. So how can we overcome this problem? What we want to do is to exploit special genes, known as gametocidal genes that are found in some wild species. These genes were discovered when breeding to produce wheat lines that had an additional segment of a chromosome from a wild relative, because some chromosomes from the wild relative were found to transmit preferentially to the offspring. These chromosomes have been termed 'cuckoo' chromosomes (or gametocidal chromosomes). Gametocidal genes on these chromosomes induce chromosomal breakages which frequently result in translocations, or exchanges, between the chromosomes of wheat and those of the wild species. This strategy provides a route for the transfer of genes from chromosomes of wild species into wheat. However it is laborious and requires extensive experience in cytogenetics. We want to be smarter in the use of this system and so we need to understand its biological basis therefore the aim of this project is to identify the genes responsible for controlling the gametocidal effect on the 4S chromosome of Aegilops sharonensis. All breeding is currently based on chromosome assortment and the ability of chromosomes to undergo meiotic recombination. Identifying the biological basis for the gametocidal effect will enable an alternative system to be more effectively exploited and deployed in plant breeding. This will ultimately enhance the genetic diversity in wheat and in particular the pool of wild species which can be exploited for wheat improvement.