PHYSIOLOGIA PLANTARUM 91: 389-394. 1 '994 Copyright © PhyMohgia Phnurum 1994 Printed in Denmark - all righrs reserved NaCl-induced changes in protoplasmic characteristics of Hordeum vulgare cultivars differing in salt tolerance M. M. F. Mansour and E. J. Stadelmann Mansour, M. M. F. and Stadelmann, E. J. 1994. NaCl-ioduced changes in protoplasmic characteristics of Hordeum vulgare cultivars differing in salt tolerance. - Physiol. Plant. 91: 389-394. Water permeability and cytoplasmic viscosity and streaming were investigated in seedlings of two Hordeum vulgare cultivars differing in salt tolerance. Six-day-old seedlings were grown for 4 additional days in Hoagland solution with and without 100 mM NaCl added. Observations and measurements were made in snhepidermal cells of the coleoptile using plasmolytic and centrifugation methods and recordings of the speed of move- nnent of microsomes. Water permeability was about the same in controls of hoth cultivars. and was decreased hy NaCl stress, hut decreased less in the tolerant cultivar. Cells from contro! plants of the stress tolerant variety had a higher cytoplasmic viscosity than cells from the moderately sensitive cultivar. Cytoplasmic viscosity in both cultivars decreased due tO' NaCl sti'ess, and more so in tl3e sensitive one, Cytoplasmic streaming was faster in the controls of the salt sensitive cultivar than in controls of the salt tolerant cultivar; NaCl had no significant effect on cytoplasmic streaming in both cuitivars. The specific responses of the cytoplasm of the sensitive and tolerant co!tivars to the salt treatment reflect differences in its structure and composition. These differences in the cytoplasm already exist hefore exposure to salt stress but some alterations of cytoplas- mic pai-ameters (e,g, water permeability) were induced by the saline environment. Key words - Cytoplasmic streaming, cytoplasmic viscosity, Hordeum vulgare, NaCl, protoplasmic characteristics, water permeability, M. M. F. Mansour (corresponding author), Dept of Botany, Fac. of Science, Ain Shams Univ., Cairo, Egypt and E. J. Stadelmann, Laboratory of Protoplasmatology, Dept of Horticultural Science, Univ. of Minnesota, St. Paul, MN 55I0S, USA. pects of the living protoplasm; cytoplasmic viscosity re- Introftuction ^^^^ ^^^ ^,^^^^ ^^^^^^ ^^ ^^ cytoplasm and also indicates Salt tolerance of glycophytes is essentially a cellular presence, hydration and interaction of macromolecules in quality (Levitt 1980, Smith andMcComb 1981, Stavarek it. Cytoplasmic streaming indirectly probes some facets and Rains 1983), and information important for under- of the metabolic activity of the cell and differences in standing the nature and mechanism of salinity toleratice passive permeability signal the differences in the lipid can be expected from studying salt responses at the cellu- portion of the cell membrane. lar level. Cytoplasmic qualities such as water permeabil- In previous papers of this series the effect of a saline ity, cytoplasmic viscosity, and cytoplasmic streatning can environment on the protoplasm of Hordeum vulgare cul- be quantitatively determined in suitable cell types. Few tivars and Triticum aestivum lines with different degrees data so far are available concerning changes of these of salt tolerance were investigated; alterations of the cell parameters of salt sensitive and salt tolerant genotypes membrane (passive solute permeability; M. F. Mansour growing in a saline environment, 1990. Ph.D. Thesis, Univ. of Minnesota, St. Paul, MN, Each of these three parameters concerns different as- USA; Mansour et al. 1993a), the o.smotic potential and Received 13 October, 1993; revised 25 February, 1994 Physiot, Plant. 91. t994 389