The role of long ncRNAs during DNA repair in Arabidopsis

Damage of DNA is frequent and requires efficient repair mechanisms to ensure correct transmission of genetic information during cell division and to progeny. While numerous repair proteins are already known, small non-protein-coding RNAs in connection with DNA damage were only recently found in different organisms. However, their origin and function are not yet known. It is expected that these molecules are processed from longer precursors, but their features and regulation remain to be investigated. Plants are especially suitable for such studies, as they are often exposed to harsh DNA damaging conditions, e.g. intense UV light exposure, and have a large repertoire of repair mechanisms. In addition, plant research offers many molecular and genetic tools for functional studies that are efficient, economic and without ethical limits. The project presented here proposes to investigate the role of damage-associated long non- protein-coding RNAs (da-lncRNAs) in DNA repair in the model plant Arabidopsis thaliana. Several candidates for such molecules generated upon DNA damage were already identified by the applicants. The project will address the following questions: (1) How are these da-lncRNAs produced and processed? (2) What are their functions during DNA repair? To investigate these aspects, the da- lncRNAs will be characterized for their origin within the genome, their structure, the control of their formation and their processing. To study their functions, it is planned to reduce or increase their level in plants, to analyze the resulting DNA repair efficiency as well as the consequences for known DNA repair mechanisms. Small RNAs molecules connected with DNA damage in animals and plants are known only for a short time, but there is no information about their origin and the potential precursors. Therefore, the project enters into an under-explored field and, in case of success, could contribute to generate novel and important insights about mechanisms of plants to protect their genetic information. This is a central process of natural evolution as well as plant breeding.

The role of long non-coding RNAs during DNA repair in Arabidopsis Damage of DNA is frequent and requires efficient repair mechanisms to ensure correct transmission of genetic information during cell division and to progeny. While numerous repair proteins are already known, a crosstalk between long noncoding RNAs (lncRNAs) and DNA repair has been recently described in several organisms, including plants. However, the molecular mechanisms and the biological functions of lncRNAs in plant DNA repair are still largely unknown. Therefore, the project aimed at addressing these questions in the model plant Arabidopsis thaliana. The project was divided into two main objectives: 1) Identify damage-associated lncRNAs (da-lncRNA) responding to DNA damage and 2) Determine the biological function of da-lncRNAs in DNA repair. I identified four da-lncRNAs responding to DNA damage induction. Their expression upon DNA damage depends on ATM, a protein involved in the DNA damage response signaling pathway, confirming a direct connection between da-lncRNA expression and DNA damage response. To determine their role in DNA repair, I generated several transgenic lines to abolish or to enhance the expression of these da-lncRNAs upon DNA damage. I observed that inhibition of da-lncRNAs expression affects plant growth and development upon DNA damage, supporting the hypothesis of their active role in DNA repair. Several studies are still on going to get more insight in the DNA repair capacity and efficiency of these da-lncRNAs upon DNA damage. Additionally, da-lncRNAs- interacting partners are investigated to determine more precisely at which steps of DNA repair process those da-lncRNAs are involved in.