Modification of Phospholipid Catabolism in Microsomal Membranes of [gamma]-Irradiated Cauliflower (Brassica oleracea L.)

Abstract

1.3.4), and lipolytic acyl hydrolase were associated with the membranes. The rate of phosphatidylcholine catabolism by the membranes increased slowly in control cauliflower during storage. y irradiation caused an immediate rise in phosphatidylcholine catabolism that remained higher than that of the controls during subsequent storage. Collectively, the data suggest that enhancement of membrane lipolytic activity results from freeradical-induced stress. Rapid increase of the membrane-associated phospholipase D activity may be a key event leading to accelerated membrane deterioration following y irradiation.

Ethylene-Mediated Phospholipid Catabolic Pathway in Glucose-Starved Carrot Suspension Cells1

“…It was also suggested that PLD and LAH were actively involved during cabbage leaf senescence (Cheour et al, 1992). Similarly, in ␥-irradiated cauliflower microsomal membranes, PLD and LAH, but not PLC, were associated with the membrane degradation, and PLD activity was primarily induced upon ␥-irradiation (Voisine et al, 1993). These findings together imply that PLD and LAH are widely involved in the phospholipid degradation under the stresses affecting cellular membranes.…”

Expression of Phospholipase D during Castor Bean Leaf Senescence

“…Changes in PLD activity were observed in a number of physiological processes, including various stress injuries (Yoshida, 1979;Chetal et al, 1982;Willemot, 1983), senescence , and seed aging and germination (Herman and Chrispeels, 1980;Di Nola and Mayer, 1986;Lee, 1989;Samama and Pearce, 1993;Wang et al, 1993). It has been proposed that PLD-mediated hydrolysis is a first step in membrane deterioration in senescing carnation flowers, tomato fruits, cabbage leaves, y-irradiated cauliflower florets, and aging cucumber and onion seeds Thompson et al, 1987;Cheour et al, 1992;McCormac et al, 1993;Samama and Pearce, 1993;Voisine et al, 1993). The resulting PLD product, PA, is further hydrolyzed by PA phosphatase and acyl hydrolases, followed by lipoxygenase.…”

The Role of Phospholipase D in Signaling Cascades1

“…PLD can be activated rapidly by stress injuries such as mechanical wounding, frost, and ␥-irradiation (Voisine et al, 1993;Ryu and Wang, 1996). Apparently, wound activation of PLD results from its translocation to membranes, which is mediated by an increase in cytoplasmic Ca 2ϩ upon wounding (Ryu and Wang, 1998).…”

“…Stimulusinduced increases in these lipid metabolites have also been found in some plant systems. Moreover, the formation of PA was shown to precede that of DAG, lysophospholipids, and free fatty acids, suggesting a possible PLD-led activation of acyl hydrolases, PLC, and/or PA phosphatase (Voisine et al, 1993;Wang, 1996, 1998;Lee et al, 1997). In addition, PA is a stimulator of PIP-5 kinase, which is responsible for the synthesis of PIP 2 (Fig.…”

“…The early studies of plant PLD functions dealt only with phospholipid breakdown during senescence, aging, and stress injuries; it was suggested that increases of PLD initiated a phospholipid degradation pathway (Voisine et al, 1993;Fan et al, 1997, and refs. therein).…”