Investigating the role of GA signaling in arbuscular mycorrhiza
Arbuscular mycorrhizal (AM) symbiosis is a mutualistic plant/fungus interaction that can be formed between almost all land plants and fungi belonging to the phylum Glomeromycota. This relationship is important because it provides plants with increased nutrient uptake, especially for limiting nutrients such as phosphorous and nitrogen. As a part of the overall effort in the Harrison lab to elucidate the molecular basis of this symbiosis, my project focused on gibberellin (GA) signaling and its role in the formation of arbuscules, the functional units of AM symbiosis. I characterized the AM phenotypes of several Medicago truncatula lines carrying mutations in genes involved in the GA signaling pathway, thereby helping to understand how GA signaling regulates arbuscule formation. I also transformed plants with constructs that allow for spatial localization of the expression of genes believed to be targets of the GA pathway.
During this internship, I learned several new techniques, including Agrobacterium rhizogenes-mediated root transformation, staining and visualization of AM fungi within roots, and histochemical staining for GUS expression. Other tasks included the generation of a promoter-GUS fusion construct, genotyping an M. truncatula mutant line, DNA and RNA isolation, fertilizer preparation, and general plant care. I worked closely with my mentor, post-doctoral fellow Daniela Floss, throughout the summer, and also received help and support from all members of the Harrison lab.