Singlet oxygen (1O2 ) and the characterization of EX1 and other protein genes involved in plant stress signaling.
Reactive Oxygen Species (ROS) are molecules that are produced naturally as a metabolic byproduct during plant metabolism. Certain abiotic and biotic factors such as high heat, drought, extreme light and pathogens act as stresses and cause the release of ROS and as a result stress responses are activated. ROS are highly reactive and can cause oxidative damage to cellular components such as proteins, lipids or DNA wherefore continuous release of ROS can be detrimental to plant cells. This can be especially devastating because of the localization of ROS in chloroplasts, a vital organelle for plant survival.
During my summer research program, the conditional flu (fluorescence) mutant of Arabidopsis thaliana was used to investigate the signaling role of one particular ROS called singlet oxygen (1O2). The FLU protein is a negative regulator of chlorophyll biosynthesis. In flu mutants a precursor of chlorophyll and a photo-sensitizer called protochlorophyllide (PChlide) accumulates in the dark and after illumination leads to the production of 1O2 resulting in transcriptional reprogramming, growth inhibition and cell death. Therefore shifting flu mutant plants from light to dark cycles enables us to study singlet oxygen in a controlled way.
Subsequent studies identified EXECTER 1 (EX1) as a signal for 1O2 and a requirement for the large transcriptional reprogramming in the nucleus resulting after the release of 1O2. Virus induced silencing was used to investigate whether other chloroplast proteins mimic EX1 in mediating stress signaling via amplification using PCR, cloning, transformation into Agrobacterium and infiltration. The plants were then analyzed for growth, cell death and transcriptional changes. Results revealed that other chloroplast proteins may be involved in 1O2 signaling.
Studying the regulation of stress in plants in response to ROS enables us to gain more insight into the ways plants acclimate to stress and successfully adjust their whole metabolism in order to cope with constant fluctuating conditions.
My Experience
During my summer research program, the conditional flu (fluorescence) mutant of Arabidopsis thaliana was used to investigate the signaling role of one particular ROS called singlet oxygen (1O2). The FLU protein is a negative regulator of chlorophyll biosynthesis. In flu mutants a precursor of chlorophyll and a photo-sensitizer called protochlorophyllide (PChlide) accumulates in the dark and after illumination leads to the production of 1O2 resulting in transcriptional reprogramming, growth inhibition and cell death. Therefore shifting flu mutant plants from light to dark cycles enables us to study singlet oxygen in a controlled way.