title: Polyamines and their cellular anti-senescence properties in honey dew muskmelon fruit.
abstract: Activated oxygen free radicals cause peroxidative damage to all membranes and hasten senescence. Polyamines (PAs) are effective scavengers of these free radicals produced by lipoxygenase (LOX) and phospholipase-D (PL-D). Five days prior to abscission (harvest), 'Honey Brew' (Cucumis melo L. (Inodorus group)) fruit have a change in the ratio of endogenous spermidine (SPD) to putrescine (PUT), from SPD>PUT to SPD<PUT, which coincides with the onset of fruit senescence. Hypodermal-mesocarp tissues from harvested fruit incubated in mannitol with exogenous SPD or spermine, at 0.25 or 0.5 M, had more chlorophyll (less senescence) following 6 or 48 h of darkness than tissues incubated in mannitol without PAs. Polyamine-incubated tissues versus no PA has less membrane peroxidation as indicated by less malondialdehyde production, and LOX and PL-D activities, and less plasma membrane perturbation as indicated by greater H(+)-ATPase activity, and protein and phospholipid contents. Prolonging the duration of endogenous SPD content, whereby, it is greater then PUT content, in harvested (fully-ripened) 'Honey Brew' fruit, could delay melon senescence and promote a longer marketable life.
authors.affiliation: Kika de la Garza Subtropical Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, 2413 E. Bus. Hwy. 83, 78596, Weslaco, TX, USA
authors.forename: G E.
authors.initials: GE
authors.lastname: Lester