This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wallace, W. Articles by Schrader, L. E. Search for Related Content PubMed PubMed Citation Articles by Wallace, W. Articles by Schrader, L. E. Agricola Articles by Wallace, W. Articles by Schrader, L. E.

Articles

Rapid Accumulation of -Aminobutyric Acid and Alanine in Soybean Leaves in Response to an Abrupt Transfer to Lower Temperature, Darkness, or Mechanical Manipulation ¹

Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706

Soybean (Glycine max [L.] Merr) leaves contain a low level (0.05 micromole per gram fresh weight) of -aminobutyric acid (Gaba) but the concentration of this non-protein amino acid increased to 1 to 2 micromoles per gram fresh weight within 5 minutes after transfer of plants or detached leaves from 33°C to 22°C or lower temperatures. A parallel decrease occurred in the concentration of glutamate. Accumulation of Gaba was also triggered by mechanical damage to the soybean leaves, but in plants subjected to a gradual reduction in temperature (2°C per minute) only a small increase in Gaba occurred. A rapid increase in the concentration of alanine and decrease in glycine occurred upon transfer of the soybean plants to darkness and was not influenced by temperature. When plants were returned to normal growing conditions, all changes in amino acid concentrations were fully reversed in 1 hour.

In soybean leaf discs incubated with [¹⁴C]glutamate, a rapid accumulation of [¹⁴C]Gaba was detected, and glutamate decarboxylase activity of the soybean leaf considerably exceeded (>30-fold) that of Gaba pyruvate transaminase. Part of the transaminase was localized in the mitochondria, but glutamate decarboxylase was not associated with any organelle or membrane component of the leaf cell. We consider that Gaba accumulation results from some change in intracellular compartmentation of the cell triggered by low temperature shock or mechanical damage. The accumulation of alanine due to a light-dark transition could be accounted for by transamination. [¹⁴C]Alanine formation was demonstrated when soybean leaf extracts were incubated with glutamate, aspartate, or serine and [¹⁴C]pyruvate.

The changes in amino acid concentrations described for soybean leaves were demonstrated for all the vegetative tissues of the soybean plant and at variable rates in the leaves of a range of plant species. The response in detached tomato (Lycopersicon esculentum Mill.) leaves was of a similar magnitude to soybean. Thus, precautions are necessary to minimize changes in amino acid composition induced by manipulation and extraction of plant material.

³ Present address: Dow Chemical USA, 2800 Mitchell Dr., Walnut Creek, CA 94598-0902.

¹ Supported by the College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI, and by the American Soybean Association Research Foundation Grant 80383 and United States Department of Agriculture/Science and Education Administration Competitive Research Grant No. 59-2551-0-1-445-0.

This article has been cited by other articles:

				T. Akihiro, S. Koike, R. Tani, T. Tominaga, S. Watanabe, Y. Iijima, K. Aoki, D. Shibata, H. Ashihara, C. Matsukura, et al. Biochemical Mechanism on GABA Accumulation During Fruit Development in Tomato Plant Cell Physiol., September 1, 2008; 49(9): 1378 - 1389. [Abstract] [Full Text] [PDF]

				W. L. Allan, J. P. Simpson, S. M. Clark, and B. J. Shelp {gamma}-Hydroxybutyrate accumulation in Arabidopsis and tobacco plants is a general response to abiotic stress: putative regulation by redox balance and glyoxylate reductase isoforms J. Exp. Bot., June 1, 2008; 59(9): 2555 - 2564. [Abstract] [Full Text] [PDF]

				A. Meyer, S. Eskandari, S. Grallath, and D. Rentsch AtGAT1, a High Affinity Transporter for {gamma}-Aminobutyric Acid in Arabidopsis thaliana J. Biol. Chem., March 17, 2006; 281(11): 7197 - 7204. [Abstract] [Full Text] [PDF]

				M. A. Perez-Amador, J. Leon, P. J. Green, and J. Carbonell Induction of the Arginine Decarboxylase ADC2 Gene Provides Evidence for the Involvement of Polyamines in the Wound Response in Arabidopsis Plant Physiology, November 1, 2002; 130(3): 1454 - 1463. [Abstract] [Full Text] [PDF]

				A. W. Bown, D. E. Hall, and K. B. MacGregor Insect Footsteps on Leaves Stimulate the Accumulation of 4-Aminobutyrate and Can Be Visualized through Increased Chlorophyll Fluorescence and Superoxide Production Plant Physiology, August 1, 2002; 129(4): 1430 - 1434. [Full Text] [PDF]

				A. M. Kumar and D. Soll Antisense HEMA1 RNA Expression Inhibits Heme and Chlorophyll Biosynthesis in Arabidopsis Plant Physiology, January 1, 2000; 122(1): 49 - 56. [Abstract] [Full Text] [PDF]

				F. J. Turano and T. K. Fang Characterization of Two Glutamate Decarboxylase cDNA Clones from Arabidopsis Plant Physiology, August 1, 1998; 117(4): 1411 - 1421. [Abstract] [Full Text]

				W. A. Snedden, N. Koutsia, G. Baum, and H. Fromm Activation of a Recombinant Petunia Glutamate Decarboxylase by Calcium/Calmodulin or by a Monoclonal Antibody Which Recognizes the Calmodulin Binding Domain J. Biol. Chem., February 23, 1996; 271(8): 4148 - 4153. [Abstract] [Full Text] [PDF]