Possesses protease activity in vitro (PubMed:25035401). Involved in the final stage of developmental programmed cell death and in intercalation of new cells. Cleaves extensins, thus probably supporting the final cell collapse (PubMed:21632425). During the compatible interaction with the biotrophic powdery mildew fungus Erysiphe cruciferarum, involved in the control of late epidermal cell death that limits growth and susceptibility to the parasite (PubMed:24605116). During anther development, involved in tapetal programmed cell death (PCD), leading to degeneration of tapetal cells and functional pollen formation (PubMed:25035401). Inhibited by leupeptin and the cysteine protease inhibitor E-64. During anther development, detected as a proenzyme in precursor protease vesicles in tapetum cells and then transported to the vacuole and transformed into the mature enzyme before rupture of the vacuole. Expressed in roots, stems, flowers, buds and green siliques. Found within columella, lateral root cap cells, and in the endodermis, the cortex and the epidermis during lateral root formation. Expressed in the abscission zones of the flower organs. Expressed when organs wither and separate from the fruit or the green silique. Expressed in unpollinated, degrading ovules (PubMed:21632425). Expressed specifically in the tapetum from stages 5 to 11 of anther development (PubMed:25035401). Reduced male fertility due to impaired pollen development and abnormal pollen exine (PubMed:25035401). Enhanced susceptibility to powdery mildew caused by the biotrophic ascomycete Erysiphe cruciferarum (PubMed:24605116). Belongs to the peptidase C1 family.