Skip to main content
NCBI home page
Plant Physiology logoLink to Plant Physiology
. 1987 Mar;83(3):596–601. doi: 10.1104/pp.83.3.596

Origin of Growth-Induced Water Potential 1

Solute Concentration Is Low in Apoplast of Enlarging Tissues

Hiroshi Nonami 1,2, John S Boyer 1,2
PMCID: PMC1056411  PMID: 16665294

Abstract

We developed a new method to measure the solute concentration in the apoplast of stem tissue involving pressurizing the roots of intact seedlings (Glycine max [L.] Merr. or Pisum sativum L.), collecting a small amount of exudate from the surface of the stem under saturating humidities, and determining the osmotic potential of the solution with a micro-osmometer capable of measuring small volumes (0.5 microliter). In the elongating region, the apoplast concentrations were very low (equivalent to osmotic potentials of −0.03 to −0.04 megapascal) and negligible compared to the water potential of the apoplast (−0.15 to −0.30 megapascal) measured directly by isopiestic psychrometry in intact plants. Most of the apoplast water potential consisted of a negative pressure that could be measured with a pressure chamber (−0.15 to −0.28 megapascal). Tests showed that earlier methods involving infiltration of intercellular spaces or pressurizing cut segments caused solute to be released to the apoplast and resulted in spuriously high concentrations. These results indicate that, although a small amount of solute is present in the apoplast, the major component is a tension that is part of a growth-induced gradient in water potential in the enlarging tissue. The gradient originates from the extension of the cell walls, which prevents turgor from reaching its maximum and creates a growth-induced water potential that causes water to move from the xylem at a rate that satisfies the rate of enlargement. The magnitude of the gradient implies that growing tissue contains a large resistance to water movement.

Full text

PDF
596

Images in this article

597Fig. 1
on p.597

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bernstein L. Method for determining solutes in the cell walls of leaves. Plant Physiol. 1971 Mar;47(3):361–365. doi: 10.1104/pp.47.3.361. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Boyer J. S. Leaf water potentials measured with a pressure chamber. Plant Physiol. 1967 Jan;42(1):133–137. doi: 10.1104/pp.42.1.133. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Boyer J. S. Relationship of water potential to growth of leaves. Plant Physiol. 1968 Jul;43(7):1056–1062. doi: 10.1104/pp.43.7.1056. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Cavalieri A. J., Boyer J. S. Water potentials induced by growth in soybean hypocotyls. Plant Physiol. 1982 Feb;69(2):492–496. doi: 10.1104/pp.69.2.492. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Cosgrove D. J., Cleland R. E. Osmotic properties of pea internodes in relation to growth and auxin action. Plant Physiol. 1983 Jun;72(2):332–338. doi: 10.1104/pp.72.2.332. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Cosgrove D. J., Cleland R. E. Solutes in the free space of growing stem tissues. Plant Physiol. 1983 Jun;72(2):326–331. doi: 10.1104/pp.72.2.326. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Cosgrove D. J., Van Volkenburgh E., Cleland R. E. Stress relaxation of cell walls and the yield threshold for growth: demonstration and measurement by micro-pressure probe and psychrometer techniques. Planta. 1984;162(1):46–54. doi: 10.1007/BF00397420. [DOI] [PubMed] [Google Scholar]
  8. Jachetta J. J., Appleby A. P., Boersma L. Use of the pressure vessel to measure concentrations of solutes in apoplastic and membrane-filtered symplastic sap in sunflower leaves. Plant Physiol. 1986 Dec;82(4):995–999. doi: 10.1104/pp.82.4.995. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Klepper B., Kaufmann M. R. Removal of salt from xylem sap by leaves and stems of guttating plants. Plant Physiol. 1966 Dec;41(10):1743–1747. doi: 10.1104/pp.41.10.1743. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Matsuda K., Riazi A. Stress-induced osmotic adjustment in growing regions of barley leaves. Plant Physiol. 1981 Sep;68(3):571–576. doi: 10.1104/pp.68.3.571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Michelena V. A., Boyer J. S. Complete turgor maintenance at low water potentials in the elongating region of maize leaves. Plant Physiol. 1982 May;69(5):1145–1149. doi: 10.1104/pp.69.5.1145. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Molz F. J. Growth-induced Water Potentials in Plant Cells and Tissues. Plant Physiol. 1978 Sep;62(3):423–429. doi: 10.1104/pp.62.3.423. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Molz F. J., Kerns D. V., Peterson C. M., Dane J. H. A circuit analog model for studying quantitative water relations of plant tissues. Plant Physiol. 1979 Nov;64(5):712–716. doi: 10.1104/pp.64.5.712. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Scholander P. F., Bradstreet E. D., Hemmingsen E. A., Hammel H. T. Sap Pressure in Vascular Plants: Negative hydrostatic pressure can be measured in plants. Science. 1965 Apr 16;148(3668):339–346. doi: 10.1126/science.148.3668.339. [DOI] [PubMed] [Google Scholar]
  15. Sentenac H., Grignon C. A model for predicting ionic equilibrium concentrations in cell walls. Plant Physiol. 1981 Aug;68(2):415–419. doi: 10.1104/pp.68.2.415. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Silk W. K., Wagner K. K. Growth-sustaining Water Potential Distributions in the Primary Corn Root: A NONCOMPARTMENTED CONTINUUM MODEL. Plant Physiol. 1980 Nov;66(5):859–863. doi: 10.1104/pp.66.5.859. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Twente J. W., Twente J. A. Regulation of hibernating periods by temperature. Proc Natl Acad Sci U S A. 1965 Oct;54(4):1044–1051. [PMC free article] [PubMed] [Google Scholar]
  18. Westgate M. E., Boyer J. S. Transpiration- and growth-induced water potentials in maize. Plant Physiol. 1984 Apr;74(4):882–889. doi: 10.1104/pp.74.4.882. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Plant Physiology are provided here courtesy of Oxford University Press

RESOURCES