Beyond degradation: Dissecting autophagy-protease relationships in plant reproduction.

Plant reproduction requires precisely timed cellular degradation to support developmental remodeling, organelle quality control, nutrient recycling, programmed cell death (PCD), and fertilization. Autophagy and protease-mediated proteolysis are major degradative systems but are often discussed either separately or as functionally linked without sufficient evidence of direct molecular coupling. Autophagy primarily mediates cargo sequestration, vacuolar delivery, metabolic remodeling, and organelle quality control. Proteases, in contrast, execute substrate cleavage, pro-enzyme maturation, nutrient mobilization, and developmentally programmed cell death (dPCD). Evidence increasingly indicates that these pathways contribute to overlapping degradative processes across reproductive development, although the molecular basis of their coordination remains poorly resolved. A key unresolved question is whether and how autophagic cargo delivery is mechanistically connected to vacuolar processing, protease activation, and terminal substrate degradation during reproduction. In this review, rather than revisiting the established functions of autophagy in reproduction, we focus on whether autophagy and protease-mediated proteolysis act independently, converge functionally, or show evidence of direct mechanistic dependence. We specifically evaluate evidence linking autophagic cargo delivery, vacuolar competence, protease activation, and terminal substrate degradation. Finally, we highlight critical knowledge gaps and research priorities needed to determine how these relationships shape fertility and reproductive resilience in angiosperms.