Hosted by: Dr. Qun Liu

Programmed cell death (PCD) is a common cellular pathway induced in plants upon abiotic and biotic stresses. The ability to modulate this process in crop plants can potentially improve resilience of agriculture productivity to drastic shifts in climate patterns. Over the past 2 decades, my lab has worked to characterize the function and activities for two classes of highly conserved cell death regulators in plants: the ER-resident Bax Inhibitor-1 (BI1) ortholog and the metacaspase protease family in the model plant Arabidopsis thaliana. With a combination of genetic and molecular approaches, we demonstrate that AtBI1 is a molecular rheostat that regulates cellular sensitivity to stresses in the ER to gate the threshold for PCD activation. Remarkably, overexpression of AtBI1 in the energy grass sugarcane, a C4 crop plant, resulted in transgenic plants that have significantly improved tolerance to water stress. In parallel to studies with this negative regulator of PCD, my group has also carried out studies to elucidate the function and control mechanisms for type II metacaspases from Arabidopsis that may work as positive switches for PCD activation. Two prototypical members of this subtype, AtMC4 and AtMC9, are highly conserved in plants and have distinct biochemical and regulatory properties. Using a domain-swap approach, recent work in our lab has revealed new information on the structure-function relationships for these proteases and generated variants with novel biochemical properties that may help to clarify their roles and function in vivo.