Involvement of the glycine-rich RNA-binding proteins (GRP) in osmotic stress response during seed germination: a comparison between GRP 2 and GRP 7

The plant glycine-rich RNA-binding proteins (GRP) are a major class of proteins known to be implicated in plant response to abiotic and biotic stress. Recent studies regarding this type of proteins focused mostly on two of them, namely GRP2 and GRP7, which are mainly involved in osmotic and oxidative plant adaptation mechanisms. The main purpose of this research was to assess the involvement of these two glycine-rich RNA-binding proteins (GRP2 and GRP7) in seed germination capacity under drought stress conditions using the model plant Arabidopsis thaliana. We observed a difference between the two mutants: grp2 seeds germinated similarly on the control medium as well as on the medium supplemented with various mannitol concentrations, while grp7-1 seeds showed a poor germination rate on all three mannitol culture mediums. In the present research work, we demonstrated that even though the two proteins GRP2 and GRP7 belong to the same family, their implication in the seed germination capacity under drought stress is opposite, one enhancing the germination, while the other is reducing it.