Unraveling regulatory gene networks involving hydrogen peroxide in plants

Reactive oxygen species (ROS) are key signalling molecules that regulate growth and development and coordinate responses to biotic and abiotic stresses. ROS homeostasis is controlled through a complex network of ROS production and scavenging enzymes. Recently, the first genes involved in ROS perception and signal transduction have been identified and, currently, we are facing the challenge to uncover the other players within the ROS regulatory gene network. The specificity of ensuing cellular responses depends on the type of ROS and their subcellular production sites. Various experimental systems, including catalase-deficient plants, in combination with genome-wide expression studies demonstrated that increased hydrogen peroxide (H2O2) levels significantly affect the transcriptome of plants and are capable of launching both defence responses and cell death events. A comparative analysis between H2O2-induced transcriptional changes and those provoked by different environmental stresses, not only consolidated a prominent role for H2O2 signalling in stress acclimation, but also allowed the identification of new candidate regulatory genes within the plant’s abiotic stress response