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Title: Evaluation of Root Exudates of Seven Sorghum Accessions

Author
item CZARNOTA, MARK - UNIVERSITY OF GEORGIA
item Rimando, Agnes
item WESTON, LESLIE - CORNELL UNIVERSITY

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2003
Publication Date: 9/1/2003
Citation: Czarnota, M.A., Rimando, A.M., Weston, L.A. 2003. Evaluation of Root Exudates of Seven Sorghum Accessions. Journal of Chemical Ecology. 29(9):2073-2084.

Interpretive Summary: Seven genetically diverse sorghum accessions were evaluated quantitatively and qualitatively for the composition of their root exudates. These included the following: two weed species, shattercane (Sorghum bicolor (L.) Moench) and johnsongrass (Sorghum halepense (L.) Pres.); two cultivated forage type sorghum - sudangrass hybrids, SX-15 and SX-17 (Sorghum bicolor x sudanense); two cultivated grain sorghum species, 8446 and 855F (Sorghum bicolor (L.) Moench); and a cultivated sweet sorghum, Della (Sorghum bicolor cv. Della). A unique capillary mat growing system was utilized to grow these Sorghum spp., and root exudates were collected. Variation existed in the amount of exudate produced. Sorgoleone was the predominant constituent identified in each accession's exudate. Other closely related compounds, including 5-ethoxysorgoleone, 2,5-dimethoxysorgoleone, three other minor components, and one unidentified component comprised the minor constituents of the root exudate. Our past work has shown that several of these compounds have potent phytotoxic activity as photosystem II inhibitors, thereby lending further support to the concept that Sorghum spp. are allelopathic and weed suppressive.

Technical Abstract: Seven sorghum accessions were evaluated quantitatively and qualitatively for the composition of their root exudates. Utilizing a unique capillary mat growing system, root exudates were collected from all sorghum accessions. Exudates were subjected to TLC and HPLC analysis to evaluate their chemical composition. Within each sorghum accession, variation existed in the amount of exudate produced and the chemical constituents of each exudate. Sorgoleone, was the predominant constituent identified in each accession's exudate. Other closely related compounds, including 5-ethoxysorgoleone, 2,5-dimethoxysorgoleone, three other minor components (MW = 364, 388, and 402), and one unidentified component comprised the minor constituents of the root exudate. Our past work has shown that several of these compounds have potent phytotoxic activity as photosystem II inhibitors, thereby lending further support to the concept that Sorghum spp. are allelopathic and weed suppressive.