Investigation of the Role of MERISTEM-DEFECTIVE (MDF) in Arabidopsis thaliana Root Development

Due to their sessile nature, plants have evolved to employ a sophisticated network of genetic and hormonal signalling pathways in order to modulate their development and responses to changing environmental conditions. Understanding these mechanisms is an important objective for plant developmental biologists and crop breeders, especially in the context of food security and climate change. Plant roots present an important target for trait optimisation due to their essential role in water and nutrient uptake from the soil. This thesis focuses on the regulatory role of splicing in root growth and development. Splicing is one of the processes involved in the generation of mature RNA, and is catalysed by a macromolecular complex known as the spliceosome. Many different components are involved in this process, potentially including the putative splicing factor gene MERISTEM-DEFECTIVE (MDF), which has been found to have a role in the organisation and maintenance of root meristems. Using Arabidopsis thaliana, this gene was investigated in order to further understand the underlying molecular mechanisms of root formation. To investigate the potential function of this putative splicing factor in the catalytic activation of the spliceosome, a yeast two-hybrid screen was conducted to explore protein-protein interactions between MDF and orthologs of human and yeast proteins known to interact with their MDF counterparts. No positive interactions were identified however, potentially due to the nature of the experimental setup. Indirect MDF-dependent regulation of root meristem-related genes was also briefly addressed. Downstream targets of MDF were examined through investigation of splicing-related genes differentially expressed and mis-spliced in mdf mutants, with a potential link identified between one of these genes, SR34, and root-specific stress responses.