Project description:Plants of different ploidy levels are separated by a strong postzygotic hybridization barrier that is established in the endosperm. Deregulated parent-of-origin specific genes are causal for the response to interploidy hybridizations, revealing an epigenetic basis of this phenomenon. In this study we present evidence that paternal hypomethylation can bypass the interploidy hybridization barrier by alleviating the requirement of the epigenetic Polycomb Repressive Complex 2 (PRC2) in the endosperm. Bypass of the barrier is mediated by suppressed expression of imprinted genes. We show that hypomethylated pollen causes redistribution of CHG methylation to PRC2 target genes, revealing that different epigenetic modifications can functionally substitute for each other. Our work presents a method and the underlying mechanism for the generation of viable triploids, providing an impressive example for the potential of epigenome manipulations for plant breeding. Examination of DNA methylation in Arabidopsis endosperm, embryo, and pollen, and gene expression in seeds
Project description:Transcriptional profiling in open flowers of Arabidopsis wild type control plants and sdg4 mutant (SALK T-DNA line_128444). The sdg4 mutant is a Arabidopsis T-DNA mutant in which T-DNA is inserted in a SET domain protein, SDG4 (At4g30860). Expression profiling studies indicate that SDG4 might function in modulating the expression of the genes that function in the growth of pollen tubes. Keywords: epigenetic modification
Project description:DNA methylation is an important epigenetic modification involved in many biological processes, and active DNA demethylation plays critical roles in regulating expression of genes and anti-silencing of transgenes. In this study, we isolated mutations in one arabidopsis gene, ROS5, which causes the silencing of transgenic 35S-NPTII because of DNA hypermethylation, but no effect on transgenic RD29A-LUC. ROS5 encodes an atypical small heat shock protein. ROS5 can physically interact with IDM1 and is required for preventing DNA hypermethylation of some endogenous genes that are also regualated by IDM1 and ROS1. We propose that ROS5 may regulate active DNA demethylation by interacting with IDM1, thereby creating a friendly chromatin environment that facilitates the binding of ROS1 to erase DNA methylation.
Project description:DNA methylation in the promoters of plant genes sometimes leads to transcriptional repression, and the wholesale removal of DNA methylation as seen in methyltransferase mutants results in drastic changes in gene expression and severe developmental defects. However, many cases of naturally-occurring DNA methylation variations have been reported, whereby the altered expression of differentially methylated genes is responsible for agronomically important traits. The ability to manipulate plant methylomes to generate populations of epigenetically distinct individuals could provide invaluable resources for breeding and research purposes. Here we describe “epimutagenesis”, a novel method to rapidly generate variation of DNA methylation through random demethylation of the Arabidopsis thaliana genome. This method involves the expression of a human Ten-eleven translocation (TET) enzyme, and results in widespread hypomethylation that can be inherited to subsequent generations, mimicking mutants in the maintenance DNA methyltransferase met1. Application of TET-mediated epimutagenesis to agriculturally significant plants may result in differential expression of alleles normally silenced by DNA methylation, uncovering previously hidden phenotypic variations.