Abstract
Ozone is a secondary air pollutant known to induce programmed cell death (PCD) in plant at high concentration. We showed that O3 induced the activation of plasma membrane anion channel which is an early prerequisite of this PCD in Arabidopsis thaliana cells. Our data further suggest interplay between anion channel activation, Ca2+ influx and ROS generation by NADPH-oxidase leading to PCD. This interplay might be fuelled by several ways in addition of direct ROS generation by O3; namely; increase in anion channel activity by oxalate generated from ascorbate degradation by O3 and H2O2 generation from apoplastic salicylic acid pool. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases which contribute to the disruption of vacuole integrity during PCD. Collectively, our data indicate that anion efflux is an early key component to morphological and biochemical events involved in O3-induced PCD.
