Red light-dependent CO/sub 2/ uptake and oxygen evolution in guard cell protoplasts of Vicia faba L. : evidence for photosynthetic CO/sub 2/ fixation

Journal Article · Fri May 01 00:00:00 EDT 1987 · Plant Physiol.; (United States)

OSTI ID:5900672

Shimazaki, K I; Zeiger, E

Suspensions of dark-adapted guard cell protoplasts of Vicia faba L. alkalinized their medium in response to irradiation with red light. The alkalinization peaked within about 50 minutes and reached steady state shortly thereafter. Simultaneous measurements of O/sub 2/ concentrations and medium pH showed that oxygen evolved in parallel with the red light-induced alkalinization. When the protoplasts were returned to darkness, they acidified their medium and consumed oxygen. Both oxygen evolution and medium alkalinization were inhibited by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU). In photosynthetically competent preparations, light-dependent medium alkalinization is diagnostic for photosynthetic carbon fixation, indicating that guard cell chloroplasts have that capacity. The striking contrast between the responses of guard cell protoplasts to red light, which induces alkalinization, and that to blue light, which activates proton extrusion, suggests that proton pumping and photosynthesis in guard cells are regulated by light quality.

• Research Organization: Stanford Univ., CA
• DOE Contract Number: AS03-81ER10924
• OSTI ID: 5900672
• Journal Information: Plant Physiol.; (United States), Vol. 84:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
VICIA
CARBON DIOXIDE FIXATION
VISIBLE RADIATION
BIOLOGICAL EFFECTS
PH VALUE
CHLOROPLASTS
OXYGEN
PHOTOSYNTHESIS
PHYSIOLOGY
PLANT CELLS
BACTERIA
CELL CONSTITUENTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
LEGUMINOSAE
MICROORGANISMS
NONMETALS
PHOTOCHEMICAL REACTIONS
PLANTS
RADIATIONS
RHIZOBIUM
SYNTHESIS
551000* - Physiological Systems