Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C3 plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C3 plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean, Glycine max (L.) Merr., contain significant quantities of fumaric acid. In fact, fumaric acid can accumulate to levels of several milligrams per gram fresh weight in Arabidopsis leaves, often exceeding those of starch and soluble sugars. Fumaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Moreover, Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.
Bibliographical noteFunding Information:
We thank Dr. Chris Somerville for many helpful suggestions regarding experiments, Dr. Bonnie Bartel for helpful suggestions regarding this manuscript, and Drs. Dave Shintani and Doug Gage for technical assistance. We also thank Dr. Seiichi Matsuda for generously allowing us to use his gas chromatograph. Financial support was provided by the U.S. Department of Energy, Energy Biosciences Program Grant DOE DE-FG03–98ER20300.
- Arabidopsis (fumaric acid)
- Fumaric acid
- Organic acid