AtGRP7 is involved in the regulation of abscisic acid and stress responses in Arabidopsis

The Arabidopsis AtGRP7 gene, encoding a glycine-rich RNA-binding protein, has been shown to be involved in the regulation of a circadian-regulated negative feedback loop. However, little is known about the role of AtGRP7 in mediating abscisic acid (ABA) and stress responses. Here, we show that AtGRP7 plays a role in both. AtGRP7 was repressed by ABA, high salt and mannitol. Disruption of AtGRP7 by T-DNA insertion led to hypersensitive responses to ABA in both seed germination and root growth assays. The atgrp7-1 mutant was also hypersensitive to osmotic stress conditions, such as high salt and high concentrations of mannitol. In addition, the atgrp7-1 mutant plants accumulated significantly higher transcript levels of two ABA- and stress-inducible genes, RD29A and RAB18, compared with the wild-type plants. Taken together, these results suggest that AtGRP7 is involved in the regulation of ABA and stress responses.