NEGATIVE REGULATION OF PLANT STRESS SIGNALING BY THE EDR1 PROTEIN KINASE

Abstract

In nature, plants endure a variety of stresses, ranging from pathogen infection to adverse environmental conditions. Although plants have evolved effective mechanisms for overcoming biotic and abiotic stress, these responses often come at the cost of growth and development. To maximize fitness, plants must carefully regulate stress signaling pathways so that they are active only when needed. The EDR1 protein kinase has been implicated as an important negative regulator of plant stress signaling. Loss-of-function edr1 mutants display enhanced sensitivity to numerous biotic and abiotic stresses. Due to the variety of phenotypes displayed by edr1 plants, EDR1 is believed to negatively regulate various plant stress signaling pathways. However, little is known about how EDR1 functions at the molecular level. My work has aimed to address some of these outstanding questions regarding EDR1 function. I have found that EDR1 directly interacts with and regulates the EDS1/PAD4 complex, which plays an important role in the regulation of plant stress responses and salicylic acid signaling. I have also shown that EDR1 physically interacts with the previously uncharacterized plant N-terminal acetyltransferase NAA50. I subsequently showed that NAA50 is essential for plant development as well as the repression of plant stress signaling. Importantly, loss of NAA50 results in a constitutive endoplasmic reticulum stress, which results in altered development and induced stress response signaling. Through the investigation of EDR1 function, I have uncovered a role for EDR1 in the negative regulation of EDS1/PAD4 signaling, as well as a link between EDR1, N-terminal acetylation, and the regulation of plant stress responses and development.