Poster: Enzymology
Abs #
244: Starch granule metabolism and acetyl-CoA utilization
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Presenter: |
Foster, Carol M., cmfoster@iastate.edu | Authors | Foster, Carol M. (A) McCarty, Shane (A) Yakobson, Alex (A) Li, Ling (A) Ilarslan, Hilal (A) Fatland, Beth L. (A) Nikolau, Basil J. (B) James, Martha G. (B) Myers, Alan M. (B) Wurtele, Eve S. (A) | | Affiliations: |
(A): Department of Genetics, Development, and Cell Biology, Iowa State University
(B): Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University
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| Web Site: | http://www.starchmetnet.org/ | |
Starch accumulates and degrades in leaf chloroplasts during the light and dark phases of the diurnal cycle, providing a stored source of energy for plant growth and metabolism. This fluctuation in starch content is integrated with the overall physiological state of the plant. One approach to investigate starch metabolism in the context of other metabolic processes is to characterize mutants in metabolic genes that are not directly associated with starch metabolism but affect normal starch accumulation. One such mutant is a dominant antisense allele (αacal) that suppresses normal expression of ATP citrate lyase (ACL). ACL produces acetyl-CoA from citrate in the cytosol; this cytosolic acetyl-CoA is required for many biochemical pathways critical to plant growth and development. Transgenic Arabidopsis with decreased levels of ACL activity contain abnormally enlarged starch granules in leaves under long day (LD) photoperiod. To study the underlying molecular events involved in utilization of acetyl-CoA during starch metabolism in wild-type (WT) and αacla1 plants, leaves of seedlings grown under continuous, long day (LD), and short day (SD) photoperiods were analyzed. Global RNA profiles and starch accumulation and metabolism were characterized. Zymogram analyses of starch metabolizing enzymes were used to compare enzyme activity to transcript accumulation profiles. Data were analyzed using SAS, GeneGobi, and GeneSpring software. In all three light conditions, αacla1 accumulated more starch than WT, but starch granules were larger in αacla1 only under continuous light and LD. Differences in internal starch granule morphology in the context of differential expression of genes implicated in starch and acetyl-CoA metabolism will be discussed.
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