USING CRISPR/CAS9 GENOME EDITING TO STUDY CLE PEPTIDE LIGANDS REGULATING ARABIDOPSIS DEVELOPMENT

All plant biomass is derived from populations of stem cells located in roots, shoots, flowers, and vascular tissues. The balance between stem cell maintenance and cell fate coordination is regulated by a negative feedback loop, which consists of a receptor kinase of the CLAVATA1 (CLV1) clade, a CLAVATA3 (CLV3)/ ENDOSPERM SURROUNDING REGION (ESR)-related (CLE) family peptide ligand, and a homeodomain transcription factor of the WUSCHEL homeobox-containing (WOX) family. The founding members of this module, CLV1, the ligand CLV3, and WUSCHEL (WUS) regulate stem cell proliferation in the shoot apical meristem and floral meristems. There are 32 Arabidopsis CLE genes, which are scattered across the genome. Almost all Arabidopsis tissues express at least three CLE genes; however, assessing the biological roles of these small signaling peptide gene families has proven to be a significant challenge due to a lack of hypomorphic or null alleles. To gain understanding into developmental processes, which are controlled by signal transduction pathways, we have performed a functional analysis of members of the CLE polypeptide family via a multiplexed CRISPR/Cas9 genome editing approach. The methods, knowledge, and plants generated in this approach will provide a foundation for the basis for research of the CLAVATA signaling pathway in plant species and will also provide a foundation for generating null alleles of small genes using a CRISP/Cas genome editing system.Doctor of Philosoph