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Production of Substances by Medicago truncatula that Affect Bacterial Quorum Sensing

September 2003 , Volume 16 , Number  9
Pages  827 - 834

Mengsheng Gao , 1 Max Teplitski , 1 Jayne B. Robinson , 2 and Wolfgang D. Bauer 1

1Department of Horticulture and Crop Science, 2021 Coffey Rd., Ohio State University, Columbus, OH 43210 U.S.A.; 2Biology Department, University of Dayton, Dayton, OH 45460-0002 U.S.A.

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Accepted 23 May 2003.

Earlier work showed that higher plants produce unidentified compounds that specifically stimulate or inhibit quorum sensing (QS) regulated responses in bacteria. The ability of plants to produce substances that affect QS regulation may provide plants with important tools to manipulate gene expression and behavior in the bacteria they encounter. In order to examine the kinds of QS active substances produced by the model legume M. truncatula, young seedlings and seedling exudates were systematically extracted with various organic solvents, and the extracts were fractionated by reverse phase C18 high-performance liquid chromatography. M. truncatula appears to produce at least 15 to 20 separable substances capable of specifically stimulating or inhibiting responses in QS reporter bacteria, primarily substances that affect QS regulation dependent on N-acyl homoserine lactone (AHL) signals. The secretion of AHL QS mimic activities by germinating seeds and seedlings was found to change substantially with developmental age. The secretion of some mimic activities may be dependent upon prior exposure of the plants to bacteria.

© 2003 The American Phytopathological Society