Regulators of polyploidy-associated gene silencing

Polyploidy, the multiplication of the diploid chromosome set containing the two parental complements, is frequent among plants. The formation of polyploid plants is often connected with transcriptional gene silencing (TGS), an epigenetic change resulting in heritable, complete loss of gene expression from previously active genes, accompanied by chemical modification of the affected DNA and its associated proteins and by structural changes of the chromatin. Epigenetics in polyploids and the underlying mechanisms are interesting in the view of basic plant biology as well as for better understanding the principles of plant breeding. Based on previous observations of polyploidy-associated transcriptional gene silencing (PA-TGS) of a resistance gene in the model plant Arabidopsis thaliana, this proposal suggests determining which trans- and cis- acting elements are involved in this regulation. The potentially reversible inactive marker gene allows for a selection- based identification of trans-acting factors, required for maintenance of the inactive state. The search can identify new factors as well as determine the role of already known gene products. Building on loss-of-function or over- expression of the identified molecules, it will be determined which parts of the genome are susceptible to PA-TGS. Inactive and active status of the same gene in diploid and polyploid plants will be compared for their chromatin features and permit addressing the role of chromosomal location and gene structure.

Polyploidy, the multiplication of the diploid chromosome set containing the two parental complements, is frequent among plants. The formation of polyploid plants is often connected with transcriptional gene silencing (TGS), an epigenetic change resulting in heritable, complete loss of gene expression from previously active genes, accompanied by chemical modification of the affected DNA and its associated proteins and by structural changes of the chromatin. Epigenetics in polyploids and the underlying mechanisms are interesting in the view of basic plant biology as well as for better understanding the principles of plant breeding. Based on previous observations of polyploidy-associated transcriptional gene silencing (PA-TGS) of a resistance gene in the model plant Arabidopsis thaliana, this proposal suggests determining which trans- and cis- acting elements are involved in this regulation. The potentially reversible inactive marker gene allows for a selection- based identification of trans-acting factors, required for maintenance of the inactive state. The search can identify new factors as well as determine the role of already known gene products. Building on loss-of-function or over- expression of the identified molecules, it will be determined which parts of the genome are susceptible to PA-TGS. Inactive and active status of the same gene in diploid and polyploid plants will be compared for their chromatin features and permit addressing the role of chromosomal location and gene structure.