Abstract <p>Snapdragon flower senescence, autolytic programmed cell death (PCD), is characterized by a series of intricate events occurring at various levels, making it a fascinating subject of investigation. Plasma membrane and cell protoplast can be disrupted under PCD-induced alternations. However, the biochemical aspects involved in these events have received comparatively less attention in scientific research. In light of this knowledge gap, the present study aimed to shed new light on the biochemical indicators associated with plasma membrane rupture. Specifically, we explored the levels of malondialdehyde content, catalase activity, total soluble protein content, endoprotease activity, proportion of endoprotease activity, antioxidant capacity (utilizing both DPPH and FRAP methods), and the ultrastructure of the plasma membrane. The results of this study revealed that in the stages before flower opening, malondialdehyde content, catalase activity, and antioxidant capacity increased. Gradually, as the flower opened and the lipid peroxidation increased, plasma membrane rupture was observed at S7. In addition, the decrease in soluble protein content was associated with an increase in the activity of endoproteases. The maximum endoprotease activity was related to cysteine proteases, serine proteases, and metalloproteases, respectively. Finally, these processes caused cytoplasmic contents to leak into the intercellular spaces.</p>