February 8 SPLS Seminar - A Forward Genetic Screen to Identify Genes Involved in 1O2-induced Cell Death and Selective Chloroplast Degradation in the Arabidopsis Thaliana Plastid Ferrochelatase Two Mutant.

Matthew Lemke
MCB PhD Student
Tuesday, February 8, 2022 - 4:00pm
https://arizona.zoom.us/j/81040445536 Password: spls2022

Plants have evolved complex signaling mechanisms to sense and respond to reactive oxygen species (ROS) generated during abiotic stresses. In particular, chloroplasts naturally generate large amounts of ROS during photosynthesis, including singlet oxygen (1O2). This localized 1O2 can damage the chloroplast and trigger quality control systems that lead to selective chloroplast degradation. This raises an intriguing question; How do plants sense chloroplast dysfunction and selectively degrade damaged chloroplasts to sustain healthy chloroplast populations?
Forward genetic screens are a valuable tool to shed light on such processes. Activation-tagging is a method that involves transforming plants with a T-DNA that carries enhancer sequences that can lead to the overexpression of nearby genes. Using this method to create secondary mutations in the fc2 mutant, an Arabidopsis mutant that expresses conditional enhancements of chloroplast degradation and cell death, we have identified eight dominant fc2 activation tagged suppressor (fas) mutants, all of which suppress conditional cell death in the adult stage. Preliminary characterization of these mutants has highlighted diverse processes that are affected and may be involved in 1O2-induced cell death and chloroplast degradation or confer general stress tolerance to overcome excess 1O2 accumulation. Further characterization of these mutants will help define the intricate mechanisms involved in 1O2-mediated chloroplast quality control (CQC) or highlight indirect systems that allow plants to tolerate abiotic stresses.
Matt is from Colorado and completed his undergraduate degree in Molecular and Cellular Biology at the University of Arizona. His work with the Woodson lab involves the use of a forward genetic approach, activation tagging, in a suppressor screen to investigate the molecular mechanisms involved in 1O2-induced chloroplast quality control. He is also exploring a potential role for microautophagy as a mechanism in the vacuolar transport of damaged chloroplasts in CQC.
In his free time, Matt enjoys hiking, cinema, photography, and traveling as much as possible.