Autophagy in plant male reproduction: conserved machinery, divergent functions

Autophagy is an evolutionarily conserved catabolic process essential for maintaining cellular homeostasis, mediating defense responses and supporting development and reproduction in eukaryotes. Despite substantial differences in reproductive strategies between plants and animals, the biogenesis of functional male gametes and the completion of fertilization in both systems rely on tightly regulated cellular degradation mechanisms. Disruption of autophagy typically causes severe defects in spermatogenesis and impairs sperm motility and fertility in animals. By contrast, autophagy is generally considered non-essential for sexual reproduction in many angiosperms as most autophagy-deficient mutants remain fertile and produce viable progeny. However, emerging evidence challenges this perspective by revealing that autophagy actually plays active yet divergent roles in pollen development, germination and pollen tube growth. A key unanswered question is how exactly autophagy contributes to male fertility and reproduction in flowering plants. In this review, we synthesize recent advances in understanding autophagy during male gametogenesis and fertilization, focusing on comparative insights between plant and animal systems to highlight mechanistic distinctions and identify essential unique questions for future plant research. We further discuss the potential involvement of alternative catabolic pathways that may act alongside canonical autophagy to regulate male gametophyte development and fertility in angiosperms.