In vivo ROS and redox potential fluorescent detection in plants: Present approaches and future perspectives

- Description of ROS origin, homeostasis and in vivo detection in plants.
- Small molecules and fluorescent dyes used for ROS and redox imaging in plants.
- Protein-based fluorescent probes to study plant redox changes and ROS production.
- Techniques and future strategies to study ROS signalling and redox changes.

Reactive oxygen species (ROS) are metabolic by-products in aerobic organisms including plants. Endogenously produced ROS act as cellular messengers and redox regulators involved in several plant biological processes, but excessive accumulation of ROS cause oxidative stress and cell damage. Understanding ROS signalling and stress responses requires precise imaging and quantification of local, subcellular and global ROS dynamics with high selectivity, sensitivity, and spatiotemporal resolution. Several fluorescent vital dyes have been tested so far, which helped to provide relevant spatially resolved information of oxidative stress dynamics in plants subjected to harmful environmental conditions. However, certain plant characteristics, such as high background fluorescence of plant tissues in vivo and antioxidant mechanisms, can interfere with ROS detection. The development of improved small-molecule fluorescent dyes and protein-based ROS sensors targeted to subcellular compartments will enable in vivo monitoring of ROS and redox changes in photosynthetic organisms.