CAN1-mediated autophagosome size regulation fine-tunes phosphate starvation tolerance in Arabidopsis thaliana
Goerg, D.; Smith, F.; Machalett, K.; Koblenz, F.; Ngo, Y. T.; Hoehne, S.; Arndt, J.; Marillonnet, S.; Grujic, N.; Imre, R.; Mechtler, K.; Dagdas, Y.; Naumann, C.
Show abstract
Inorganic phosphate (Pi) availability determines root development and plant performance. In Arabidopsis thaliana, external Pi is sensed by root tips and Pi limitation triggers ER stress-induced autophagy, yet the physiological impact and mechanisms controlling autophagosome biogenesis remain unclear. Here, we identify CAN1 (COMPONENT OF AUTOPHAGIC NETWORK) as a novel plant-specific regulator of autophagosome size in local Pi sensing. CAN1 associates with the plasma membrane-ER tethering protein VAP27-1 and binds to Pi-responsive ATG8 isoforms through conserved interaction motifs. Loss of CAN1 augments ER stress resistance by reducing autophagosome size in Pi-deprived root tips. Our findings establish CAN1 as a determinant of autophagosome size at the ER membrane. Thus, CAN1 functions as a molecular link between Pi-dependent ER stress signaling and fine-tuning of autophagic capacity.
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