0000000000464828
AUTHOR
Russell L. Jones
Effects of Ga3 and Ca2+ on barley aleurone protoplasts: a freeze-fracture study
Freeze-fracture electron microscopy was used to study changes in the endomembrane system of barley (Hordeum vulgare L. cv. Himalaya) aleurone protoplasts. Protoplasts were used for this study because their response to calcium and the plant hormone gibberellic acid (Ga3) can be monitored prior to rapid freezing of cells for electron microscopy. Protoplasts incubated in Ga3 plus Ca2+ secrete elevated levels of a-amylase relative to cells incubated in Ga3 or Ca2+ alone. The endoplasmic reticulum (ER) and Golgi apparatus of protoplasts incubated in Ga3 plus Ca2+ undergo changes that are well correlated with the synthesis and secretion of a-amylase. The ER, which appears as short, single sheets …
The Effect of Secretion on Lipids and their Distribution in Barley Aleurone Protoplasts
Barley aleurone protoplasts, when exposed to Ga3 and Ca2+ synthesize and secrete the hydrolytic enzyme α -amylase (Bush et al., 1986). At the same time, protoplasts undergo important structural changes which reflect the elaboration of the membrane system involved in protein synthesis and secretion. The mobilization of lipid reserves may be a preliminar step which would provide energy as well as several components for the synthesis of membrane lipids.
Gibberellic acid stimulates lipid metabolism in barley aleurone protoplasts
Abstract Changes in the lipid composition of barley aleurone protoplasts following incubation in the presence or absence of gibberellic acid (GA) were studied and correlated with cell development. Analysis of neutral lipids in protoplast extracts and purified lipid bodies provide evidence for the strong effect of GA on the mobilization of storage lipids. In vivo protoplast staining with the membrane marker N -phenyl-l-naphthylamine (NPN) and phospholipid determinations of protoplast extracts show an increase in membrane lipids during protoplast incubation. GA stimulates phospholipid metabolism by increasing the synthesis of phosphatidyl ethanolamine and phosphatidyl choline, the major phosp…