Natural Variability in clv2 Phenotypes

Plants develop continually throughout their lifetime from central regions of growth, called meristems, that contain dividing cells that will either differentiate to form organs or remain undifferentiated in what is called the stem cell niche. Maintenance of this stem cell niche by signaling molecules is necessary for proper development, as this niche allows for new organs to be made over the course of the plant’s life. The CLAVATA2 (CLV2) leucine-rich repeat receptor-like protein inhibits stem cell proliferation in the shoot meristem. Mutations in clv2 lead to an overproduction of stem cells, resulting in increased organ number. Additionally, clv2 mutants in the Arabidopsis thaliana Columbia (Col-0) ecotype have a secondary phenotype with disruption in production of flowers, but this effect is not seen in the Landsberg-erecta (Ler-0) ecotype. The cause of this phenotypic variation is unknown. Here, we analyze the genetic basis of this phenotypic discrepancy using mapping-by-sequencing supplemented with fine marker mapping to identify regions of the genome linked to CLV2-mediated ¬flower development. We determined the nature of this genetic relationship to be a semi-dominant, multigenic interaction and identified a 150 Kb region of chromosome 5 that is linked to the clv2 terminating flower phenotype seen in Col-0. To further investigate this phenotype, we used CRISPR-Cas9 in 17 additional genetically and geographically diverse Arabidopsis ecotypes to mutate clv2. Comparing clv2 phenotypes across ecotypes could reveal how flower development is linked with adaptations in local environments. This genetic link provides insight into how floral signaling is robustly maintained across geographically divergent environments, and has potential implications with regards to crop production in Earth’s changing climate.Bachelor of Scienc