Smiling in the Face of Adversity: Molecular and Evolutionary Mechanisms Behind Copper Tolerance in Mimulus guttatus

Abstract

This study investigates the molecular and evolutionary mechanisms underlying copper tolerance in Mimulus guttatus. I focused on the role of multi-copper oxidases (MCOs), specifically the T-MCO gene located in the Tol1 locus in Mimulus guttatus, to provide direct evidence of its contribution to the plant’s copper tolerance mechanism. The T-MCO gene was overexpressed in non-tolerant backgrounds of M. guttatus and Arabidopsis thaliana, with results indicating that T-MCO is central to copper tolerance in M. guttatus. While MCO-centered mechanisms were previously associated primarily with bacteria and fungi, this finding suggests a novel copper tolerance mechanism in plants. Transgenic A. thaliana lines exhibited enhanced germination rates and root growth across various copper concentrations, confirming the significant impact of T-MCO overexpression. I used generalized linear mixed models (GLMMs) to validate these findings, highlighting the importance of T-MCO in copper homeostasis. This research advances our understanding of plant copper tolerance mechanisms and suggests potential applications in crop development. Future work should explore T-MCO’s interactions within the copper homeostasis network and its applicability in other plant species.