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Gamma‐ray‐induced changes in hypodermal mesocarp tissue plasma membrane of pre‐ and post‐storage muskmelon
Author(s) -
Lester Gene E.,
Whitaker Bruce D.
Publication year - 1996
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1996.980207.x
Subject(s) - cucumis , sterol , phospholipid , atpase , catabolism , chemistry , biochemistry , enzyme , irradiation , biology , food science , membrane , horticulture , cholesterol , physics , nuclear physics
Gamma irradiation (1.0 kGy) of intact, newly harvested, mature muskmelon fruit ( Cucumis melo L. var. reticulatus Naud.) appears to have an immediate deleterious effect, but also a long‐term beneficial effect, on the integrity and function of the plasma membrane (PM) of hypodermal mesocarp tissue. The initial consequences of gamma irradiation included an increase in the free sterol:phospholipid ratio, resulting at least in part from deglycosylation of steryl glycosides, a decrease in the spinasterol:7‐stigmastenol ratio in each of the PM steryl lipids (free sterols, steryl glycosides, and acylated steryl glycosides), and a decrease in H + ‐ATPase activity. Irradiation did not increase protein loss, suggesting that the decrease in H + ‐ATPase activity resulted from either direct inactivation of the enzyme or altered PM ordering caused by the steryl lipid modifications. The long‐term beneficial effects of irradiation, observed following 10 days of commercial storage, included greater retention of total PM protein, a diminished decline in total PM phospholipids (PL) and in the PL:protein ratio, and maintenance of greater overall H + ‐ATPase activity (activity was the same as in controls on a per mg protein basis, but there was > 30% more protein in the PM of stored irradiated fruit). These results indicate that 1 kGy gamma irradiation administered prior to storage slowes the progression of two key parameters of senescence, PM protein loss and PL catabolism.