PhytoMethDev HRZZ project

Duration of the project:

1/3/2017 - 28/02/2021

Funding agency:

Croatian Science Foundation

DNA methylation is one of several epigenetic mechanisms used by cells to control gene expression. It is a commonly used epigenetic signalling tool that can fix genes in the “off” or „on“ state. The process of DNA methylation is vital for a number of cellular processes such as embryonic development, chromosome stability, X-chromosome inactivation, genomic imprinting, gene suppression, and biotic and abiotic stress responses.

In plants epigenetic diversity besides regulating development, presumably contribute in the plant phenotypic and physiological plasticity and the ability to survive and reproduce in unpredictable environments. This makes plants a preferred model in the epigenetic field. Plant DNA methylation occurs at CG, CHG and nonsymmetrical CHH (where H is A, C or T) sequences, each of which has different genetic requirements for its preservation. Nonsymmetrical CHH methylation cannot be sustained by the maintenance machinery and require de novo methylation in each cell cycle through a process called RNA-directed DNA methylation (RdDM). Besides being specific for CHH methylation, RdDM induces all de novo cytosine methylation in all sequence contexts. Two plant specific RNA polymerases, Pol IV and Pol V produce small interfering RNAs and long non-coding RNAs respectively, which are important for RNA-DNA target sequence recognition. DDR complex represents a major determinant that is proposed to be responsible for recruitment of Pol V enzyme to the specific loci, but the mechanism is still not clear. Our preliminary results indicate that Arabidopsis BPM proteins recognize and interact with the DDR complex and thus might mediate the positioning of RdDM machinery. On the other hand, recent findings indicate that substrates of BPM proteins are predominantly transcription factors (Lechner et al. 2011, Chen et al. 2013, 2015). These two properties of a single BPM protein suggest its capacity to act as a control switch between methylation (mediated by RNA Pol V) and transcription (mediated by RNA PolII). The main goal of this project is to elucidate the functional roles of BPM1 (and possibly other BPMs) in orchestrating transcriptional regulation and RdDM, as well as its possible role during plant embryogenesis and stress adaptation.