Alterations in growth, photosynthesis, and respiration in a starchless mutant of Arabidopsis thaliana (L. ) deficient in chloroplast phosphoglucomutase activity
A mutant of Arabidopsis thaliana (L.) Heynh. which lacks leaf starch was isolated by screening for plants which did not stain with iodine. When grown in a 12-h photoperiod, leaves of the wild-type accumulated substantial amounts of starch but lower levels of soluble sugars. Under these conditions, the mutant accumulated relatively high levels of soluble sugars. Rates of growth and net photosynthesis of the mutant and wild-type were indistinguishable when the plants were grown in constant illumination. However, in a short photoperiod, the growth of the mutant was severely impaired, the rate of photosynthesis was depressed relative to the wild-type, and the rate of dark respiration, which was high following the onset of darkness, exhibited an uncharacteristic decay throughout the dark period. The depressed photosynthetic capacity of the mutant may also reflect a metabolic adaptation to the accumulation of high levels of soluble carbohydrate which mimics the effects of alterations in source/sink ratio. The activities of sucrose phosphate synthase and acid invertase are significantly higher in the mutant than in the wild-type whereas ADP-glucose pyrophosphorylase activity is lower. This suggests that the activities of these enzymes may be modulated in response to metabolite concentrations or flux through the pathways.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- AC02-76ER01338
- OSTI ID:
- 5820035
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 79:1; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ARABIDOPSIS
BIOSYNTHESIS
CARBOHYDRATES
CELL CONSTITUENTS
CHEMICAL REACTIONS
CHLOROPLASTS
ENZYME ACTIVITY
ENZYMES
GROWTH
HYDROLASES
LEAVES
LIGASES
MUTANTS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT GROWTH
PLANTS
POLYSACCHARIDES
REAGENTS
RESPIRATION
SACCHARIDES
STARCH
SYNTHESIS