Mechanisms and Regulation of Senescence: An Overview on Hormonal and Oxidative Perspective

Senescence in plants represents a crucial developmental phase involving the regulated degradation of cellular components, enabling the remobilization of nutrients to support growth and reproduction. This review focuses on cotyledon senescence occurring during early seedling development. Cotyledon senescence is characterized by complex physiological, biochemical, and molecular processes including chlorophyll degradation, macromolecular breakdown, and dynamic hormonal signaling. Hormones such as ethylene, cytokinins, and abscisic acid (ABA) play antagonistic roles in regulating the timing and progression of senescence. Additionally, the interplay between reactive oxygen species (ROS) and antioxidant defense systems forms a pivotal aspect of senescence regulation, acting both as cellular damage agents and signaling molecules. Despite significant advances, the signaling networks linking embryonic axis development with cotyledon senescence continues to be lacking. Unraveling these pathways may offer insights into seedling establishment and improve our knowledge of plant developmental biology.