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Dowgert MF, Wolfe J, Steponkus PL. The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion. Plant Physiol. 1987;83(4):1001-7doi: 10.1104/pp.83.4.1001.
Dowgert, M. F., Wolfe, J., & Steponkus, P. L. (1987). The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion. Plant physiology, 83(4), 1001-7. https://doi.org/10.1104/pp.83.4.1001
Dowgert, M F, et al. "The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion." Plant physiology vol. 83,4 (1987): 1001-7. doi: https://doi.org/10.1104/pp.83.4.1001
Dowgert MF, Wolfe J, Steponkus PL. The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion. Plant Physiol. 1987 Apr;83(4):1001-7. doi: 10.1104/pp.83.4.1001. PMID: 16665314; PMCID: PMC1056490.
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Plant Physiol. 1987 Apr;83(4):1001-7. doi: 10.1104/pp.83.4.1001.

The Mechanics of Injury to Isolated Protoplasts following Osmotic Contraction and Expansion.

Plant physiology

M F Dowgert, J Wolfe, P L Steponkus

Affiliations

  1. Department of Agronomy, Cornell University, Ithaca, New York 14853-0144.

PMID: 16665314 PMCID: PMC1056490 DOI: 10.1104/pp.83.4.1001

Abstract

Micro-osmotic manipulation was used to determine the influence of osmotic contraction on the expansion potential of individual protoplasts isolated from rye (Secale cereale L. cv Puma) leaves. For protoplasts isolated from leaves of nonacclimated plants (NA protoplasts), osmotic contraction in sufficiently hypertonic solutions (>1.53 osmolal) predisposed the protoplasts to lysis during osmotic expansion when they were returned to isotonic conditions (0.53 osmolal). In contrast, for protoplasts isolated from leaves of cold acclimated plants (ACC protoplasts), osmotic contraction in either 2.6 or 4.0 osmolal solutions was readily reversible. Following osmotic contraction, the resting tension (gamma(r)) of NA protoplasts was similar to that determined for protoplasts in isotonic solutions (i.e. 110 +/- 22 micronewtons per meter). In contrast, gamma(r) of ACC protoplasts decreased from 164 +/- 27 micronewtons per meter in isotonic solutions to values close to zero in hypertonic solutions. Following expansion in hypotonic solutions, gamma(r)'s of both NA and ACC protoplasts were similar for area expansions over the range of 1.3 to 1.6. Following osmotic contraction and reexpansion of NA protoplasts, hysteresis was observed in the relationship between gamma(r) and surface area-with higher values of gamma(r) at a given surface area. In contrast, no hysteresis was observed in this relationship for ACC protoplasts. Direct measurements of plasma membrane tension (gamma) during osmotic expansion of NA protoplasts from hypertonic solutions (1.53 osmolal) revealed that gamma increased rapidly after small increments in surface area, and lysis occurred over a range of 1.2 to 8 millinewtons per meter. During osmotic expansion of ACC protoplasts from hypertonic solutions (2.6 osmolal), there was little increase in gamma until after the isotonic surface area was exceeded. These results are discussed in relation to the differences in the behavior of the plasma membrane of NA and ACC protoplasts during osmotic contraction (i.e. endocytotic vesiculation versus exocytotic extrusion) and provide a mechanistic interpretation to account for the differential sensitivity of NA and ACC protoplasts to osmotic expansion from hypertonic solutions.

References

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