Plastid-to-nucleus communication, signals controlling the running of the plant cell

► Plastids emit signals that regulate nuclear gene expression. ► Tetrapyrroles, phosphonucleotides and peptides are potential plastid signals. ► Changes of the redox state of PET and accumulation of ROS trigger plastid signaling. ► Plastid signals play important roles in a wide range of cellular processes. ► Chloroplasts play a critical role as sensors of changes in the growth environment.