Meiotic recombination: how has this adaptive and evolutionary force been influenced by domestication and selective breeding?

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Plant domestication and the origin of agriculture date from ca. 10,000 years ago and have had profound effects on genome evolution demonstrated in the dramatic phenotypic differences between wild progenitors and domesticated crops. The transition from wild to domesticated plants followed by selective breeding has led to a reduction of genetic diversity. In this proposal we propose that meiotic recombination has played a key role in the reduction of genetic diversity in crops and the difference in genetic diversification between wild and crop species. Meiotic recombination is the basic process of sexual reproduction in germs cells that exchanges genetic information between chromosomes breaking the linkage between genes to form new allelic combinations. Meiotic recombination is a powerful force for plant genome evolution and adaptation to local environment as well as during breeding.Meiotic recombination and the intense selection during breeding have highly influenced plant genome evolution, but it remains unclear how these two processes are connected. In this project, we will evaluate how meiotic processes have diverged during breeding to effectively reduce genetic variation in crops. We will use advanced genomic technologies to sequence the DNA molecules bound to meiotic recombination proteins and profile the landscape of meiotic recombination genome-wide in wild and domesticated wheat. These new datasets will be unique due to their high-resolution and will allow us to explore local recombination rate over genes to test the genetic effects of domestication and to understand the differing evolutionary trajectories between natural and agricultural environments. This project will also address an essential knowledge gap as it will determine if genes of agricultural relevance that have been under strong selection during breeding have retained recombinational properties for further genetic improvements. Initial investigations will be carried out on trehalose phosphate synthase (TPS) and trehalose phosphate phosphatase (TPP). TPSs and TPPs determine the way sugars in plants are allocated which strongly affects plant adaptation to environment, growth and development and crop yields; they are important targets in crop improvement. With the knowledge generated in this project it will be possible to understand how some of the genetic variation in TPSs and TPPs has been lost during the crop selection process. We will also investigate local recombination rate over meiotic genes to test whether they too have been fixed by selective breeding. This will enable us to understand how loss of genetic diversity for important genes has reduced the adaptive potential to create novel genetic diversity. Overall, this project will generate high resolution and genome-wide recombination data to gain key insights in gene evolution between natural and agricultural environments. Our research initially focuses on three gene families but could be extended to any gene families in future studies. Hence, this project addresses a key fundamental question in evolutionary biology with the potential to establish new concepts on the genetic effects of domestication and to promote the strategic mission of NERC in "Population genetics and evolution".