description
- It is vital that we continue to improve and adapt our most important crops to meet the challenges of an increasing global population and the changing climate. A major component of crop improvement is via classical crop breeding. In this approach breeders combine varieties of crops with complementary beneficial characteristics and use the natural process of recombination to recover strains that combine both sets of desirable features from the original parents. Recombination occurs between the generations when plants form sex cells (gametes) and therefore by understanding the processes that occur at this stage we will be able to breed useful strains faster and more effectively. This is important as recombination patterns can severely limit our ability to breed crop species. For example, if we consider the extremely large wheat genome (~16x larger than the human genome), recombination shows a highly skewed distribution and occurs in a minority of the DNA sequence. Despite large parts of the wheat genome being essentially silent for recombination, these regions can contain many important genes and useful variation. Therefore, these patterns can inherently limit the ability of breeders to improve our crops. As one example, the dwarfing gene RhtD1, which contributed to yield increases achieved during the Green Revolution, is located in one such non-recombining region. This has limited the ability of breeders to combine RhtD1 with other useful genes located in proximity, including important disease resistance genes. This problem is known as linkage-drag. We are investigating the hypothesis that a major cause for suppressed recombination in these genomic regions is at the level of organisation that we term epigenetic. This concept describes organisation of the genome beyond the DNA base sequence itself. A well understood example of this is that the cytosine bases in the DNA can be modified with methyl groups and this modification can act as a type of grammar that influences how the DNA is expressed. We have previously shown that epigenetic information can have a major effect on patterns of recombination. In the proposed work we will alter epigenetic information in plant genomes and profile exactly how the recombination process changes. We will undertake this both in the model species Arabidopsis and also directly in the complex wheat genome. This will involve collaboration with the group of Pierre Sourdille (Clermont-Ferrand) who is an expert at mapping recombination in the hexaploid bread wheat genome. This proposal is also an industrial collaboration with Meiogenix who are pioneering advanced technology to direct the recombination machinery to specific locations in the genome. They key idea in this proposal is to combine these targeting technologies with manipulation of chromatin to effectively unlock recombination in silent regions of plant chromosomes. Through this work we will provide knowledge and technology that will allow variation to be accessed in breeding programmes that was previously unavailable, due to restricted distributions of recombination. These ambitious research aims capitalise on the unique knowledge and research experience of the partners and will bring novel approaches to solving the problem of recombination control.