Methionine sulfoxide reductases and cadmium-induced abiotic stress: is NO an intermediary?

AA MENDEZ; MP BENAVIDES; LB PENA; SM GALLEGO

Congreso; International Plant Molecular Biology Congress.; 2015

Proteins are macromolecules that can suffer oxidative post-translational modifications (MPT) induced by reactive oxygen species (ROS). An example of these MPT is the oxidation of the thioether moiety of methionine to the sulfoxide (MetSO). This event damages the structure and activity of proteins, but it may be reversed by the presence of methionine sulfoxide reductases (MSR). Five genes for MSRA and nine for MSRB have been identified in A thaliana, coding for proteins with different subcellular locations. These sequences are associated to a higher stress tolerance and yield in transgenic plants. The present work demonstrates that MSR family is involved in the abiotic stress response in plants. After treating 20 d-old Arabidopsis thaliana (Col 0) plants with 100 µM Cl2Cd for 3 d, a raise in protein carbonylation, lower chlorophyll content, higher ROS levels in chloroplasts and NO content in leaves was observed. Further analysis had shown a decrease in ascorbate (APX) and guaiacol (GPX) peroxidases, whilst catalase (CAT) activity was higher in Cd-treated plants. This treatment produced a boost in transcription levels of all the MSR. Interestingly, pre-exposition of plants to 100 µM sodium nitroprusside, a NO donor, before cadmium treatment, prevented all the above mentioned. Our results indicate that the MSR family takes part in a general response pattern to oxidative stress induced by cadmium, affecting all MSR isoforms. Although NO seems to have no direct effect on the MSR transcripts levels, it may be acting as an antioxidant or as an antioxidant system regulator.