Embryo-specific aspartic protease that limits programmed cell death during reproductive development. Possesses peptidase activity toward casein in vitro. Expressed specifically in developing gametophytes and developing seeds. Embryonic lethality when homozygous. Ectopic expression of PCS1 induces survival of cells of the anther wall including stomium and septum cells. This leads to a failure in anther dehiscence and subsequent male sterility (PubMed:15723040). Belongs to the peptidase A1 family.