Grant: Discovery Grants Program - Individual

DNA is subjected to continuous attack, from both toxic byproducts of cellular metabolism and a variety of physiochemical environmental agents. Protection mechanisms include DNA repair and chromatin modifications. While DNA repair has been extensively studied, little is known of the details of chromatin modification. Chromatin remodeling, DNA and histone methylation, and histone acetylation are key processes that allow plants to cope with damage and help "adapt" to possible new threats. Do all stresses trigger similar kinds of epigenetic response, or is there a signature response for each individual stress? Which DNA repair components, or lack there of, have the most profound effect on chromatin remodeling? How stable are changes in methylation patterns over numerous generations? To answer these and other questions, we propose to employ several transgenic and non-transgenic whole plant and cell-extract based repair assays utilizing an in vivo luciferase-based and in vitro â-glucuronidase-based homologous recombination, mismatch repair, and point mutation repair substrates. Arabidopsis thaliana mutants deficient in DNA repair, methylation ability, and stress response will be compared for their repair capacity under UV, salt, drought, and temperature stresses. We will monitor changes in epigenetic regulation by performing global-genome assays and locus-specific methylation assays such as ROPS, COBRA, as well as histone modification (methylation and acetylation) assays. Specific attention will be drawn to ddm1, mom, and sde1 mutants, as these mutants could potentially have problems establishing appropriate methylation changes upon exposure to stress. In order to detect transgenerational epigenetic changes, we will collect seeds from treated mutant and wild-type plants, and loci specific changes in methylation status will be compared to the expression patterns of genes in the proximity of the changes. Our study is designed to identify the epigenomic 'hallmarks' of various stresses, and will establish a solid link between stress response, genome stability, DNA repair capacity, and epigenetic control over chromatin modifications.