Effects of triadimefon and osmotic stress on plasma membrane composition and ATPase activity in white spruce (Picea glauca) needles

1993 ◽  
Vol 87 (4) ◽  
pp. 475-482 ◽  
Author(s):  
Eva Sailerova ◽  
Janusz J. Zwiazek
Keyword(s):  
Plasma Membrane ◽  
Osmotic Stress ◽  
Atpase Activity ◽  
Picea Glauca ◽  
White Spruce ◽  
Membrane Composition

Ultrastructure of the endocytotic pathway in glutaraldehyde-fixed and high-pressure frozen/freeze-substituted protoplasts of white spruce (Picea glauca)

1993 ◽  
Vol 106 (3) ◽  
pp. 847-858
Author(s):  
M.E. Galway ◽  
P.J. Rennie ◽  
L.C. Fowke
Keyword(s):  
High Pressure ◽  
Plasma Membrane ◽  
Picea Glauca ◽  
Time Course ◽  
Freeze Substitution ◽  
White Spruce ◽  
Specific Marker ◽  
Cationized Ferritin ◽  
High Pressure Freezing ◽  
Coated Pits

An ultrastructural study of endocytosis has been made for the first time in protoplasts of a gymnosperm, white spruce (Picea glauca), fixed by high-pressure freezing and freeze substitution. Protoplasts derived from the WS1 line of suspension-cultured embryogenic white spruce were labelled with cationized ferritin, a non-specific marker of the plasma membrane. The timing of cationized ferritin uptake and its subcellular distribution were determined by fixing protoplasts at various intervals after labelling. To address concerns about using chemical fixation to study the membrane-bound transport of cationized ferritin, protoplasts were fixed both by conventional glutaraldehyde fixation and by rapid freezing in a Balzers high-pressure freezing apparatus (followed by freeze substitution). Cationized ferritin appeared rapidly in coated pits and coated vesicles after labelling. Later it was present in uncoated vesicles, and in Golgi bodies, trans-Golgi membranes and partially coated reticula, then subsequently in multivesicular bodies, which may ultimately fuse with and deliver their contents to lytic vacuoles. The results show that the time course and pathway of cationized ferritin uptake in the gymnosperm white spruce is very similar to the time course and pathway elucidated for cationized ferritin uptake in the angiosperm soybean. High-pressure freezing yielded much better preservation of intracellular membranes and organelles, although plasma membranes appeared ruffled. Protoplasts fixed by both methods possessed numerous smooth vesicles in the cortex and smooth invaginations of the plasma membrane. These became labelled with cationized ferritin, but apparently did not contribute directly to the internalization of cationized ferritin, except via the formation of coated pits and vesicles from their surfaces.

scholarly journals Conjugated Polyamines in Root Plasma Membrane Enhanced the Tolerance of Plum Seedling to Osmotic Stress by Stabilizing Membrane Structure and Therefore Elevating H+-ATPase Activity

2022 ◽  
Vol 12 ◽  
Author(s):  
Hongyang Du ◽  
Benxue Chen ◽  
Qiang Li ◽  
Huaipan Liu ◽  
Ronald Kurtenbach
Keyword(s):  
Plasma Membrane ◽  
Drought Stress ◽  
Osmotic Stress ◽  
Atpase Activity ◽  
Membrane Structure ◽  
Membrane Damage ◽  
Cellular Level ◽  
Water Retention Capacity ◽  
Retention Capacity ◽  
Conjugated Polyamines

Polyamines are small positively charged molecules in plants and play important functions in many biological processes under various environmental stresses. One of the most confounding problems relating to polyamines (PAs) in stresses is the lack of understanding of the mechanisms underlying their function(s). Furthermore, a limited number of studies have addressed this issue at the sub-cellular level, especially in tree plants under drought stress. Therefore, in this research, by simulating natural drought stress with polyethylene glycol (PEG) osmotic stress, the relationship between the levels of conjugated polyamines and the activity of H+-ATPase in the plasma membrane was elucidated with the roots of two plum (Prunus salicina L.) cultivars, which were different in drought tolerance, as experimental materials. Furthermore, free PA levels and the activities of S-adenosylmethionine decarboxylase (SAMDC) and transglutaminase (TGase), which were closely associated with the levels of free and conjugated PAs, were also detected. Results showed that under osmotic stress, the increases of the levels of non-covalently conjugated (non-CC) spermidine (Spd) and spermine (Spm), covalently conjugated (CC) putrescine (Put) and Spd in the plasma membrane of drought-tolerant Ganli No. 5 were more significant than those of drought-sensitive Suli No. 3, indicating that these conjugated PAs might be involved in the tolerance of plum seedlings to stress. Furthermore, the conjugated PAs were closely correlated with plum seedling growth, water retention capacity, plasma membrane damage degree, and hydrogen (H+)-ATPase activity in the plasma membrane. To get more complementary pieces of evidence, we subjected plum seedlings to combined treatments of PEG and exogenous PA (Spd and Spm), and an inhibitor of SAMDC [methylglyoxal-bis (guanylhydrazone), (MGBG)] or TGase (o-phenanthroline). These results collectively suggested that non-CC Spd and Spm, CC Put and Spd in plasma membrane might function in enhancing the tolerance of plum seedlings to osmotic stress by stabilizing membrane structure and therefore elevating H+-ATPase activity.

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