Modification of carbon partitioning, photosynthetic capacity, and O{sub 2} sensitivity in Arabidopsis plants with low ADP-glucose pyrophosphorylase activity
- Washington State Univ., Pullman, WA (United States)
Wild-type Arabidopsis plants, the starch-deficient mutant TL46, and the near-starchless mutant TL25 were evaluated by noninvasive in situ methods for their capacity for net CO{sub 2} assimilation, true rates of photosynthetic O{sub 2} evolution (determined from chlorophyll fluorescence measurements of photosystem II), partitioning of photosynthate into sucrose and starch, and plant growth. Compared with wild-type plants, the starch mutants showed reduced photosynthetic capacity, with the largest reduction occurring in mutant TL25 subjected to high light and increased CO{sub 2} partial pressure. The extent of stimulation of CO{sub 2} assimilation by increasing CO{sub 2} or by reducing O{sub 2} partial pressure was significantly less for the starch mutants than for wild-type plants. Under high light and moderate to high levels of CO{sub 2}, the rates of CO{sub 2} assimilation and O{sub 2} evolution and the percentage inhibition of photosynthesis by low O{sub 2} were higher for the wild type than for the mutants. The relative rates of {sup 14}CO{sub 2} incorporation into starch under high light and high CO{sub 2} followed the patterns of photosynthetic capacity, with TL46 showing 31% to 40% of the starch-labeling rates of the wild type and TL25 showing less than 14% incorporation. Overall, there were significant correlations between the rates of starch synthesis and CO{sub 2} assimilation and between the rates of starch synthesis and cumulative leaf area. These results indicate that leaf starch plays an important role as a transient reserve, the synthesis of which can ameliorate any potential reduction in photosynthesis caused by feedback regulation.
- OSTI ID:
- 305474
- Journal Information:
- Plant Physiology (Bethesda), Vol. 119, Issue 1; Other Information: PBD: Jan 1999
- Country of Publication:
- United States
- Language:
- English
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