Potassium chloride as stomatal osmoticum in Allium cepa L. , a species devoid of starch in guard cells
KCl was, in general, the major osmoticum in guard cells, irrespective of whether stomata had opened on leaves or in epidermal strips floating on solutions. The solute requirement varied between 50 and 110 femtomoles KCl per micrometer increase in aperture per pair of guard cells. Stomata did not open on solutions of K iminodiacetate, presumably because its anion could not be taken up. Stomata opened if KCl or KBr was provided. Taken together, the results indicate that the absence of starch from guard cells deprived them of the ability to produce malate in amounts of osmotic consequence and that the presence of absorbable Cl/sup -/ (or Br/sup -/) was necessary for stomatal opening. Previous nutrient supply of the plants determined whether the charges of K/sup +/ in guard cells were completely balanced by Cl/sup -/ or only partially. Addition of K/sub 2/SO/sub 4/ to the nutrient solution reduced the participation of Cl/sup -/ in stomatal ion transfer, even if epidermal strips of these plants were later exposed to KCl solution. Although malate appeared not to participate in stomatal ion transfer in onion, epidermal samples of this species did contain malate. Malate accumulated in the epidermis of leaves put into the light but disappeared from illuminated epidermal strips floating on solutions. In whole leaves, epidermal malate content was positively correlated with stomatal opening; in epidermal strips floating on solutions, the correlation was negative or absent.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- EY-76-C-02-1338
- OSTI ID:
- 5375116
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 65:1; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
551000 -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALLIUM CEPA
ANIONS
BIOLOGICAL EFFECTS
BIOLOGY
BODY
CARBOHYDRATES
CATIONS
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
CYTOLOGY
DIFFUSION
EPIDERMIS
EPITHELIUM
HALIDES
HALOGEN COMPOUNDS
IONS
MORPHOLOGY
OPENINGS
ORGANIC COMPOUNDS
ORGANS
OSMOSIS
OXYGEN COMPOUNDS
PLANT CELLS
PLANTS
POLYSACCHARIDES
POTASSIUM CHLORIDES
POTASSIUM COMPOUNDS
POTASSIUM SULFATES
REAGENTS
SACCHARIDES
SKIN
STARCH
STOMATA
SULFATES
SULFUR COMPOUNDS
TISSUES