Linking redox and calcium signaling via thioredoxins

Reactive oxygen species (ROS) and calcium (Ca2+) are well-established second messengers in plants that transmit signals from an initial stimulus to initiate downstream cellular processes, and play crucial roles in plant development and responses to adverse environmental conditions. Upon perception of stimuli, transient increases in ROS and cytosolic free calcium concentration ([Ca2+]cyt) act as early signals. Later, Ca2+ signals regulate ROS homeostasis by controlling ROS generation, but reciprocally, ROS can modulate Ca2+ signaling via post-translational modifications (PTMs) in specific proteins involved in the transport, sensing, and transmission of the Ca2+ signal. Thioredoxins (TRXs) act as ROS scavengers, being able to revert the oxidized, nitrosated, persulfided, and glutathionylated forms of specific proteins, acting as a reversible PTM mechanism that contributes to fine-tune protein function. In this review, we summarize the crosstalk between Ca2+ and ROS signaling, focusing on the involvement of TRXs.