Description of the thesis topic

Investigating the role of small RNA movement in plant adaptation to stress Project description The movement of small RNAs is essential for plant development and defense against stress. It is known that small RNAs move systemically through the plant vasculature as well as from cell to cell via cytoplasmic connections called plasmodesmata. Moreover, the movement of small RNAs has the potential to induce epigenetic changes in receptor tissues. We aim to investigate the contribution of small RNA movement to the stress response, and more specifically the function of their long-range communication. We want to investigate whether small RNAs from maternal somatic tissues can move to reproductive tissues using transgenic expression of DNA hairpins and sensors. Our laboratory has already used this approach to study the movement and function of small RNAs within the female gametophyte. In this project, we would like to apply this strategy to study the transport of small RNAs from the mother plant (sporophyte) to the next generation (gametes, albumen or embryo). In a pilot study, we recently observed a non-cell-autonomous signal from sporophyte to albumen in around 1% of seeds. In this project, the PhD student will characterize in detail this movement as well as the vascular and cytoplasmic connections in reproductive tissues using both electron and confocal microscopy. The development of the vasculature and cell-to-cell connections in the mature ovule or seed will be studied as these are tissues where the vasculature terminates and the vascular contents are released. In parallel, he/she will study the role of certain small RNA-interacting proteins called Argonaute, which show a particular enrichment in reproductive tissues where the vasculature ends. We will destabilize them in a cell-specific manner to understand their function. Finally, the student will analyze whether and how this transgenerational movement of small RNAs could be influenced by stress and modify the methylome of the next generation. Time permitting, this study could be extended to other plant models with different vascular connections. Different stresses could influence this movement, potentially increasing the next generation's adaptation to stress. A better understanding of such phenomena is key to appreciating how the next-generation plant can be better adapted to its environment.

Work Context

Feasibility over 3 years The project described is based on preliminary data and material already existing in our laboratory. Our team is expert in the field of small RNAs in Arabidopsis, particularly in the study of their movement in reproductive tissues. In addition, the project will benefit from all the necessary infrastructure available at IBMP, including greenhouses, growth chambers and technical platforms such as microscopy, Illumina and nanopore sequencing, and gene expression analysis. The project is expected to be completed within three years. Supervision of the PhD student For this project, the PhD student will initially receive supervision until he/she acquires sufficient autonomy. He/she will be enrolled in the Life Sciences Doctoral School and will be scientifically supervised by the group leader and receive daily guidance from more experienced researchers in the group. In addition, the PhD student will benefit from the synergistic environment at IBMP, where several teams are exploring gene expression processes in plants.

Constraints and risks

Possible risks associated with working in a molecular biology laboratory, risks associated with chemical products, biological agents, thermal environments, work on screens.

Additional Information

Skills required: The ideal candidate for this PhD is curious, motivated and diligent, holding a master's degree or equivalent in biological sciences with a solid theoretical grounding in molecular biology or plant genetics. Interest or experience in the fields of small RNAs, epigenetics, microscopy, plant genetics, biology, high-speed sequencing and RNA-seq data analysis is a plus.