Figure 1.

Proposed model of autophagy regulation by ROS in plants and algae. The intracellular level of ROS is modulated by different signals, including high-light stress, nutrient limitation, ER stress, or pathogen infection. ROS ultimately lead to ATG1 activation and hence autophagy induction either via TOR signaling or a TOR-independent mechanism, denoted here as X. This unknown pathway might control autophagy through ATG1 regulation, as reported in mammalian cells for AMPK (SnRK1 in plants), or by a different mechanism as described for the ATG4 protease. See text for details. DPI, Diphenylene iodonium; NF, norflurazon; rap, rapamycin; tun, tunicamycin.