Exploring the Physiological, Biochemical and Molecular Dynamics of Flower Development and Senescence in Antirrhinum majus L.

This study investigates the intricate physiological, biochemical and molecular mechanisms underlying flower development in Antirrhinum majus. Scanning electron microscopy (SEM) revealed significant alterations in petal surface architecture, transitioning from tightly arranged ridges and folds in the bud stage to smooth, flattened surfaces during senescence. Soluble protein content exhibited a gradual decline from the bud stage to full bloom, followed by a pronounced reduction in senescence, paralleling the expression patterns of the defender against death (DAD1). Lipid peroxidation increased progressively from the bud to bloom phases due to low activity of lipoxygenase and transcript levels of corresponding gene LOX1, with a sharp escalation during senescence, driven by elevated LOX1 expression, resulting in membrane disintegration. Hormonal regulation was crucial, with ethylene and ABA concentrations peaking during senescence, concomitant with enhanced transcription of ACO (1-aminocyclopropane-1-carboxylic acid oxidase) and AAO3 (abscisic aldehyde oxidase 3). Biochemical analysis revealed a marked decline in antioxidant enzyme activities, including superoxide dismutase, catalase and ascorbate peroxidase, alongside a significant increase in LOX activity. These findings provide insights into the coordinated physiological and molecular processes driving floral senescence in A. majus.