Physiological function of chloroplast-produced reactive oxygen species in plant response to stresses

Abstract

Chloroplasts are one of the major sources of reactive oxygen species (ROS), and therefore are also sources of oxidative signaling. Recently we have created the system for chemical-inducible suppression of thylakoid membrane-bound ascorbate peroxidase (tAPX) in Arabidopsis plants in order to clarify physiological function of oxidative signaling via ROS derived from chloroplasts. Microarray analysis revealed that ROS derived from chloroplasts affect the expression of a large number of genes, some of which are involved in plant response to chilling and pathogens. Here we analyzed the effect of tAPX suppression on plant sensitivity to stresses.
The suppression of tAPX expression decreased expression of the genes encoding key regulators of chilling signaling, and thus increased plant sensitivity to chilling stress, while it decreased the transcript levels of genes involved in pathogen response without increasing salicylate level. These findings suggest that the oxidative signaling via ROS derived from chloroplasts is involved in response to abiotic and biotic stresses. Now, we are analyzing the effect of tAPX suppression on plant sensitivity to elicitors and pathogen.