Cysteine protease involved in xylem tracheary element (TE) autolysis during xylogenesis in roots. Participates in micro autolysis within the intact central vacuole before mega autolysis is initiated by tonoplast implosion (PubMed:18573193). Involved in susceptibility to the bacterial plant pathogen Ralstonia solanacearum (PubMed:24947605). Interacts with PRN2. Predominantly vacuolar. May be associated to plasma membrane. Mostly expressed in roots, stems and flowers. Confined to tracheary elements, and specifically to xylem. No visible phenotype under normal growth conditions, but mutant plants show increased resistance to infection by the bacterial wilt pathogen Ralstonia solanacearum. Belongs to the peptidase C1 family.