Negative regulator of abscisic acid (ABA) responses during seed germination. H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Binds 2 magnesium or manganese ions per subunit. During germination, expressed in the embryo, vascular bundles and the root cap. In 6-day-old seedlings, expression in seed coat/endosperm disappears is detected only at the bases of the lateral root buds. Expressed in developing an mature siliques from 10 to 16 days after flowering (DAF). By ABA. Hypersensitivity to ABA, salt and sucrose during seed germination. Belongs to the PP2C family.