Scope and Method of Study:

This study used ozone to induce ROS stress in Medicago truncatula. Techniques used include microarray analysis, suppression subtraction hybridization, differential screening of EST libraries, real time PCR, lipid peroxidation assay, ascorbate-glutathione assays, ROS assays, and gradient fractionation to isolate polyribosome bound mRNA.

Findings and Conclusions:

It was found that within the naturally occurring Medicago truncatula population there exists great diversity for the symptoms seen in response to ozone. Both resistant and sensitive accessions up regulated many of the same gene networks but at different times and to magnitude. There was a rapid general decrease in polyribosome loading in response to ozone in resistant plants. Coupled with the massive transcriptional changes this could provide for an early reprogramming of the cells to an adaptive response in resistant plants. The initial passive response, or a lack of active response, in sensitive plants leads to oxidative stress via ROS buildup and ultimately oxidative cell death.