O/sub 2/-insensitive photosynthesis in C/sub 3/ plants: its occurrence and a possible explanation. [Phaseolus vulgaris; Xanthium strumarium L. ; Scrophularia desertorum (Shaw. ) Munz]

Journal Article · Tue Jan 01 00:00:00 EST 1985 · Plant Physiol.; (United States)

OSTI ID:5022641

Sharkey, T D

Leaves of C/sub 3/ plants which exhibit a normal O/sub 2/ inhibition of CO/sub 2/ fixation at less than saturating light intensity were found to exhibit O/sub 2/-insensitive photosynthesis at high light. This behavior was observed in Phaseolus vulgaris L., Xanthium strumarium L., and Scrophularia desertorum (Shaw.) Munz. O/sub 2/-insensitive photosynthesis has been reported in nine other C/sub 3/ species and usually occurred when the intercellular CO/sub 2/ pressure was about double the normal pressure. A lack of O/sub 2/ inhibition of photosynthesis was always accompanied by a failure of increased CO/sub 2/ pressure to stimulate photosynthesis to the expected degree. O/sub 2/-insensitive photosynthesis also occurred after plants had been water stressed. Under such conditions, however, photosynthesis became O/sub 2/ and CO/sub 2/ insensitive at physiological CO/sub 2/ pressures. Postillumination CO/sub 2/ exchange kinetics showed that O/sub 2/ and CO/sub 2/ insensitivity was not the result of elimination of photorespiration. It is proposed that O/sub 2/ and CO/sub 2/ insensitivity occurs when the concentration of phosphate in the chloroplast stroma cannot be both high enough to allow photophosphorylation and low enough to allow starch and sucrose synthesis at the rates required by the rest of the photosynthetic component processes. Under these conditions, the energy diverted to photorespiration does not adversely affect the potential for CO/sub 2/ assimilation.

• Research Organization: Desert Research Institute, Reno, Nevada
• DOE Contract Number: FG08-84ER13234
• OSTI ID: 5022641
• Journal Information: Plant Physiol.; (United States), Vol. 78:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
OXYGEN
BIOLOGICAL EFFECTS
PHOTOSYNTHESIS
INHIBITION
VISIBLE RADIATION
RESPONSE MODIFYING FACTORS
CARBON DIOXIDE FIXATION
CHLOROPLASTS
EXPERIMENTAL DATA
GAS FLOW
LEAVES
PHOSPHATES
RESPIRATION
WATER
CELL CONSTITUENTS
CHEMICAL REACTIONS
DATA
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUID FLOW
HYDROGEN COMPOUNDS
INFORMATION
NONMETALS
NUMERICAL DATA
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
SYNTHESIS
550501* - Metabolism- Tracer Techniques