As the world’s population grows, we must seek to enhance food production. One hurdle in the way of achieving this goal is the devastating loss caused by plant pathogens and
pests. Plants are not completely defenseless against pathogenic attack and utilize a
multilayered immune system to prevent disease. Recognition of pathogens involves
dynamic signaling that activates multiple outputs with the overall goal of resistance. One
of these outputs is the generation of reactive oxygen species (ROS) during pathogen
recognition. In plants, production of ROS during infection is mediated by membrane
localized NADPH oxidases which are more commonly known as respiratory burst
oxidase homologs (RBOHs). Our understanding of activation of RBOHs is derived from
research on RBOHD from Arabidopsis thaliana. However, our knowledge of how
RBOHs are negatively regulated has been limited. In this dissertation, I studied a
pathway that negatively regulates stability of RBOH and ROS production in Arabidopsis
(Arabidopsis thaliana) and Tomato (Solanum lycopersicum). My results show that
RBOHD is negatively regulated through crosstalk between phosphorylation and
ubiquitination, which involves PIRE, an E3 ubiquitin ligase. Further analysis revealed
that PIRE is conserved in land plants as are the phosphorylation signaling residues in
RBOH homologs. Finally, utilizing gene editing tools, I show that this conserved
pathway can be exploited to enhance production of ROS and disease resistance in
tomato. Collectively, this dissertation work details the characterization of a novel
regulatory pathway for RBOHD in A. thaliana and highlights the potential to utilize this
knowledge as a foundation for translational work in tomato with the goal of enhancing
resistant to pathogens.