Summary
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 of membrane in Ca2+-and Ga3-treated protoplasts, exists as a series of long fenestrated stacks of membranes following incubation in Ga3 plus Ca2+. The Golgi apparatus is also more highly developed in protoplasts treated with Ga3 plus Ca2+. This organelle is larger and has more vesicles associated with its periphery in protoplasts that actively secrete a-amylase. Evidence that the Golgi apparatus participates in a-amylase secretion is also provided by experiments with the ionophore monensin, which causes pronounced swelling of Golgi cisternae and inhibits the secretion of a-amylase. We interpret these observations as showing that the ER and Golgi apparatus of barley aleurone participate in the intracellular transport and secretion of a-amylase. The plasmalemma (PF face) of barley aleurone protoplasts shows a high density of intramembranous particles (IMPs) which, in general, are evenly distributed. Occasionally, ordered arrays of IMPs are observed, possibly resulting fro m osmotic stress. after 48 hours the plasmalemma of some Ga3-treated protoplasts show particle-free areas considered to be indications of senescence.
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Abbreviations
- ER:
-
endoplasmic reticulum
- Ga3 :
-
gibberellic acid
- IEF:
-
isoelectric focusing
- IMP:
-
intramembranous particle
- PF:
-
protoplasmic fracture
- PL:
-
plasmalemma
References
Branton D, Bullivant S, Gilula NB, Karnovsky MJ, Moore H, Muhlethaler K, Northcote DH, Packer L, Satir B, Satir P, Speth V, Staehelin LA, Steere RL, Weinstein RS (1975) Freeze-etching nomenclature. Science 190: 54–56
Bush DS, Cornejo MJ, Huang CN, Jones RL (1986) Ca2+-stimulated secretion ofα-amylse during development in barley aleurone protoplasts. Plant Physiol 82: 566–574
Buttrose MS (1971) Ultrastructure of barley aleurone cells as shown by freeze-etching. Planta 96: 13–26
Carbonell J, Jones RL (1984) a comparison of the effects of Ca2+ and gibberellic acid on enzyme synthesis and secretion in barley aleurone. Physiol Plant 63: 345–350
Chrispeels MJ (1976) Biosynthesis, intracellular transport and secretion of extracellular molecules. annu Rev Plant Physiol 27: 19–38
Davey MR, Matthias RJ (1979) Close-packing of plasma membrane particles during wall regeneration by isolated higher plant protoplasts-fact or artifact? Protoplasma 100: 85–99
Evins WH, Varner JE (1971) Hormone controlled synthesis of endoplasmic reticulum in barley aleurone cells. Proc Natl acad Sci USA 68: 1631–1633
Fernandez DE, Staehelin La (1985) Structural organization in ultra rapidly frozen barley aleurone cells actively involved in protein secretion. Planta 165: 455–468
Gordon-Kamm WJ, Steponkus PL (1984) The influence of cold acclimation on the behavior of the plasma membrane following osmotic contraction of isolated protoplasts. Protoplasma 123: 161–173
Gubler F, Jacobsen JV, Ashford AE (1986) Involvement of the Golgi apparatus in the secretion ofα-amylase from gibberellin-treated barley aleurone cells. Planta 168: 447–452
Heupke HJ, Robinson DG (1985) Intracellular transport ofα-amylase in barley aleurone cells: evidence for the participation of the Golgi apparatus. Eur J Cell Biol 39: 265–272
Huang CM, Cornejo MJ, Bush DS, Jones RL (1986) Estimating viability of plant protoplasts using double and single staining. Protoplasma 135: 80–87
Jacobsen JV, Beach LR (1985) Control of transcription ofα-amylase and rRNA genes in barley aleurone protoplasts by gibberellic and abcisic acid. Nature 316: 275–277
—,Zwar JA, Chandler PM (1985) Gibberellic acid-responsive protoplasts from mature aleurone of Himalaya barley. Planta 163: 430–439
Jones RL (1969 a) The fine structure of barley aleurone cells. Planta 85: 359–385
— (1969 b) Gibberellic acid and the fine structure of barley aleurone cells. I. Changes during the lag-phase ofα-amylase synthesis. Planta 87: 119–133
— (1969 c) Gibberellic acid and the fine structure of barley aleurone scells. II. Changes during the synthesis and secretion ofα-amylase. Planta 88: 73–86
— (1980) The isolation of endoplasmic reticulum from barley aleurone layers. Planta 150: 58–69
— (1985) Protein synthesis and secretion by the barley aleurone: a perspective. Israel J Bot 34: 377–395
—,Jacobsen JV (1983) Calcium regulation of the secretion ofα-amylase isoenzymes and other proteins from barley aleurone layers. Planta 158: 1–9
—,Price JM (1970) Gibberellic acid and the fine structure of barley aleurone cells. III. Vacuolation of the aleurone cell during the phase of ribonuclease release. Planta 94: 191–202
—,Varner JE (1967) The bioassay of gibberellins. Planta 72: 155–161
Melroy D, Jones RL (1986) The effect of monensin on intracellular transport and secretion ofα-amylase isozymes in barley aleurone. Planta 167: 252–259
Morré DJ, Boss WJ, Grimes A, Mollenhauer HH (1983) Kinetics of Golgi apparatus membrane flux following monensin treatment of embryogenic carrot cells. Eur J Cell Biol 30: 25–32
—,Morré DM, Mollenhauer HH, Deutter W (1987) Golgi apparatus cisternae of monensin-treated cells accumulate in the cytoplasm of liver slices. Eur J Cell Biol 43: 235–242
Obata T, Suzuki H (1976) Gibberellic acid-induced secretion of hydrolases in barley aleurone layers. Plant Cell Physiol 17: 63–71
Paleg LG, Hyde B (1964) Physiological effects of gibberellic acid. VII. Electron microscopy of barley aleurone cells. Plant Physiol 39: 673–680
Platt-Aloia KA, Thomson WW (1985) Freeze-fracture evidence of gel-phase lipid in membranes of senescing cowpea cotyledons. Planta 163: 360–369
Pyliotis NA, Ashford AE, Whitecross MI, Jacobsen JV (1979) Localization of gibberellic acid-induced acid phosphatase activity in the endoplasmic reticulum of barley aleurone cells with the electron microscope. Planta 147: 134–140
Robenek H, Peveling E (1977) Ultrastructure of the cell wall regeneration of isolated protoplasts ofSkimmia japonica Thumb. Planta 136: 135–145
Schnabl H, Vienken J, Zimmermann U (1980) Regular arrays of intra membranous particles in the plasmalemma of guard cell and mesophyll cell protoplasts ofVicia faba. Planta 148: 231–237
Vigil EL, Ruddat M (1973) Effect of gibberellic acid and actinomycin D on the formation of endoplasmic reticulum in barley aleurone cells. Plant Physiol 51: 549–558
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Cornejo, M.J., Platt-aloia, K.A., Thomson, W.W. et al. Effects of Ga3 and Ca2+ on barley aleurone protoplasts: a freeze-fracture study. Protoplasma 146, 157–165 (1988). https://doi.org/10.1007/BF01405925
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DOI: https://doi.org/10.1007/BF01405925