Investigating the role of plant heat shock proteins during oxidative stress.

Oxidative stress, arising from an imbalance in the generation and removal of reactive oxygen species (ROS), is a challenge faced by all aerobic organisms. In plants, different pathways sense ROS from extracellular sources or organelles such as mitochondria, chloroplast or peroxisome. In our recent paper on Plant Molecular Biology1 we have studied the Arabidopsis thaliana early response to the generation of superoxide anion in chloroplasts during active photosynthesis. Transcript profile analysis revealed that the expression level of various genes encoding heat shock proteins (Hsps), increased after a short term of oxidative stress treatment. Furthermore, there was an induction of heat shock transcription factors HsfA2 and HsfA4A that were reported to be regulators of genes involved in stress response of Arabidopsis.1,2In this addendum, we complement the expression analysis of two Hsp genes encoding Hsp70 and a 17.6 kDa class I small heat-shock protein (sHsp), and discuss their plausible role during oxidative stress, considering our data and other recently published papers.