Involvement of DNA Repair Proteins in Gene Transcription Regulation During Plant Immune Responses
We will test our hypothesis that DNA damage repair (DDR) proteins participate in plant immunity not only to facilitate defense gene expression through chromatin remodeling but also to maintain chromatin stability by repairing possible transcription-associated DNA damage using the following approaches: (1) We will first perform a genome-wide survey of genes bound by RAD51 (a downstream DDR protein) using chromatin immunoprecipitation (ChIP) followed by sequencing. This survey will allow us to determine whether pathogen-induced association of RAD51 is limited to the few genes that we have tested or is a genome-wide phenomenon. (2) Through the genome-wide survey, we will be able to pick the specific target genes for which the mutation rates in both wild-type and DDR mutants (i.e., rad51 and brca2) will be measured in response to pathogen challenge using DNA sequencing. Because mutations occur at very low frequencies, calculating the mutation rates and comparing them in wild-type and DDR mutants may be technically challenging.
Through this project, we will gain better understanding of the biological and evolutionary significance of the DDR involvement in plant immunity. The same experiments can also be performed using human cell lines with wild-type and defective BRCA2 genes to address the question why mutating BRCA2, a protein involved in DNA damage repair for all cell types, specifically enhances cancer occurrence in the breast and the ovary.