Effect of chromatin modification on meiosis:wheat, a model for polyploid crops

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This project will address an important problem that has hampered the efficient exploitation of the genetic diversity in wild relatives to dramatically increasing wheat’s performance (yield, introduce disease resistance and drought tolerance). We want tools which will allow the exploitation of this diversity. What stops wild relatives being used efficiently? The wild relative and the wheat chromosomes must align and efficiently exchange (recombine) during meiosis. Without recombination, there isn't the opportunity to introduce the genetic diversity of wild relatives into wheat. The Ph1 locus substantially reduces recombination between wild relative and wheat chromosomes, making gene transfer from wild relatives difficult. We will overcome this problem by understanding Ph1’s regulation of recombination. Deletion mutants of the Ph1 locus exist, but once the Ph1 locus is removed, the chromosomes undergo extensive rearrangement, and so the wild relative chromosome is trying to exchange with a rearranged wheat chromosome. An understanding of the Ph1 locus will enable it to be switched off with one generation to allow the wheat and wild relative chromosomes to exchange. Wild relative chromosomes of wheat exhibit extensive gene synteny along their chromosome length, and their genes exhibit more than 95% sequence homology. Despite this level of similarity, there is little recombination between wild relative and wheat chromosomes at meiosis with Ph1 present. Deletion of the Ph1 locus allows the chromosomes to behave like homologous chromosomes and recombine. Recombination involves the initiation of double strand breaks within genic regions and then repair of breaks. Thus Ph1 is affecting the genic regions enabling them to be recognised, or not for recombination. By exploiting next generation sequencing and cell biological approaches, we will identify what is being altered and treat developing wheat anthers prior to meiosis with drugs which themselves induce similar changes.

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