Molecular components of stress-responsive plastid retrograde signaling networks and their involvement in ammonium stress.

Plastid retrograde signaling (chloroplast to nucleus) has been proposed to play an important role in the acclimation of plant function to environmental stress. Although several pathways and molecular components, as well as some signals, have been identified in recent years, our understanding of the communication between plastid and nucleus under stress remains fragmentary. This mini-review summarizes the properties of currently proposed candidate signals, chief molecular components, and their roles in the plastid retrograde signaling network in a variety of stress responses. We provide special emphasis on the recently characterized AMOS1/EGY1-dependent plastid retrograde signaling pathways engaged during ammonium stress.