Emerging Roles of Polyamines and Autophagy in Plant In Vitro Regeneration

Plant regeneration demonstrates the remarkable developmental plasticity of plants, enabling tissue repair, organ formation, and adaptation to environmental challenges through cellular reprogramming and redifferentiation. This capacity underpins numerous horticultural and biotechnological applications, including grafting, micropropagation, somatic embryogenesis, organogenesis, and genetic transformation. While regeneration has traditionally been explained by the coordinated actions of auxin and cytokinin together with key developmental regulators such as WUSCHEL, BABY BOOM, and WUSCHEL-related homeobox genes, recent studies indicate that regeneration is also influenced by stress signaling, metabolic reprogramming, reactive oxygen species, and epigenetic regulation. Among these regulatory components, polyamines have emerged as important modulators of cell division, differentiation, stress responses, and morphogenic competence during in vitro regeneration. Likewise, autophagy, a conserved intracellular recycling pathway, has gained increasing attention for its role in maintaining cellular homeostasis, facilitating metabolic adaptation, and supporting developmental transitions under tissue culture conditions. This review summarizes current knowledge on the independent roles of polyamines and autophagy in plant cell reprogramming and in vitro regeneration, with particular emphasis on wound responses, somatic embryogenesis, and organogenesis. In addition, it highlights common physiological processes through which these pathways may influence regeneration and identifies the limited understanding of their potential relationship as an important direction for future research.