The precise regulation of plant growth hormones enables plants to integrate environmental and developmental cues effectively. Polyamines have recently emerged as important growth regulators that enhance plant tolerance to environmental stresses. Leaf senescence is a genetically programmed process governed by coordinated phytohormonal actions that reorganize biochemical and physiological pathways, ultimately leading to cell death. The present study examines the role of polyamines (PAs) in modulating biochemical and physiological processes associated with delayed senescence in leaf discs of Saxifraga stolonifera L. Leaf discs were treated with putrescine (Put; 20 μM), spermidine (Spd; 15 μM), and spermine (Spm; 15 μM), while distilled water treated discs served as controls. PA-treated leaf discs retained their green coloration and fresh appearance for approximately four days longer than controls, indicating delayed senescence. This delay was correlated with sustained and elevated activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), as well as higher chlorophyll content. Polyamine treatments also enhanced membrane stability and soluble protein levels, which were associated with reduced specific protease activity. Furthermore, exogenous PAs alleviated oxidative stress, as evidenced by decreased lipid peroxidation. These findings demonstrate that polyamines delay leaf senescence by mitigating oxidative damage and maintaining chlorophyll and protein integrity in leaf tissues.
Altaf et al. (2026) studied this question.