Polyamines Delay the Senescence of Antirrhinum majus L. Flowers by Coordinating Various Physiological and Biochemical Mechanisms

Coordinated by intricate crosstalk between various phytohormones, petal senescence characterizes an extraordinary stage of flower development, involving precisely regulated biochemical and physiological reprogramming. The process involves a gradual deterioration of physiological processes and structural integrity, eventually leading to the death of the flowers. Polyamines are small organic compounds that play crucial roles in plant growth, development and stress. These compounds are involved in various physiological processes, including cell division, flowering, fruit set and maturation. Given this, the current study elucidates the potential role of polyamines in regulating the senescence of cut spikes of Antirrhinum majus. Spikes, harvested with a minimum of two buds at one day before the anthesis stage, were treated with different polyamines such as Putrescine (Put), Spermidine (Spd) and Spermine (Spm) at 0.25 and 0.75 mM concentrations. A separate set of flower spikes was maintained in distilled water, which served as the control. Our results indicated that polyamines delayed the senescence of A. majus significantly leading to an extended postharvest lifespan of flower spikes. Among these treatments, 0.75 mM Put was the most effective treatment in enhancing the longevity of A. majus. On the contrary, the control spikes showed early senescence. The study showed that polyamines accentuated the activity of antioxidant enzymes and enhanced membrane stability, besides reducing lipoxygenase activity and ethylene content in flowers. Moreover, polyamines significantly increased the content of soluble proteins, total phenols and sugar fractions in the floral tissues. Also, polyamines reduced bacterial growth and improved solution uptake in flowers. The investigation elucidated that the polyamines regulate the flower senescence of A. majus by orchestrating various physio-biochemical processes.