Abstract
Cryptogein, a protein from a pathogenic oomycete, rapidly triggers cytosolic Ca2+ rise and production of reactive oxygen species (ROS), followed by synchronous induction of defense-related gene expression, cell cycle arrest and PCD in tobacco BY-2 cells. To analyze the possible involvement of autophagy in the regulation of plant immunity, we have established a transgenic BY-2 cell line in which dynamics of autophagosomes can be visualized with various fluorescent proteins fused with the tobacco homolog of Atg8, and analyzed the effects of cryptogein and cell cycle phases on the dynamics of autophagosomes. We also tested effects of various autophagy modulators on cryptogein-triggered initial signaling events including Ca2+ mobilization and ROS production, as well as gene expression and PCD. We will discuss novel regulatory mechanisms of plant immune responses involving autophagy, and possible potentiation of plant immunity by modulating autophagy.