(a) The cis-element is located in the 2.2-kb region encoding the C-terminal cytosolic portion of SOS1 protein. C, control; Na, 200 mm NaCl treatment for 5 h. Tubulin and rRNA were used as loading controls.
(b) The approximate 500-bp sequence within the 2.2 kb is required for instability of SOS1 mRNA. Deletion constructs of the 2.2 kb (left panel) were made and transgenic plants were obtained as described in Experimental procedures. Two independent T2 transgenic lines were used to detect the mRNA level in the transgenic plants (right panel). Vertical dotted lines show the sequence region (approximately 500 bp) required for SOS1 mRNA instability. C, control; Na, 200 mm NaCl treatment for 5 h; H2O2, 10 mm H2O2 treatment for 1 h. rRNA (as a loading control) is not shown.