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Mode of Action, Localization of Production, Chemical Nature, and Activity of Sorgoleone: A Potent PSII Inhibitor in Sorghum spp. Root Exudates

Published online by Cambridge University Press:  20 January 2017

Mark A. Czarnota*
Affiliation:
University of Georgia, Department of Horticulture, 1109 Experiment Street, Griffin, GA 30223
Rex N. Paul
Affiliation:
USDA/ARS/SWSRU, Stoneville, MS 38776
Franck E. Dayan
Affiliation:
USDA/ARS/NPURU, University, MS 38667
Chandrashekhar I. Nimbal
Affiliation:
33 King Avenue, Fremont, CA 94536
Leslie A. Weston
Affiliation:
Department of Horticulture, Cornell University, Ithaca, NY 14853
*
Corresponding author's E-mail: [email protected].

Abstract

The root exudates produced by sorghums contain a biologically active constituent known as sorgoleone. Seven sorghum accessions were evaluated for their exudate components. Except for johnsongrass, which yielded 14.8 mg root exudate/g fresh root wt, sorghum accessions consistently yielded approximately 2 mg root exudate/g fresh root wt. Exudates contained four to six major components, with sorgoleone being the major component (> 85%). Three-dimensional structure analysis was performed to further characterize sorgoleone's mode of action. These studies indicated that sorgoleone required about half the amount of free energy (493.8 kcal/mol) compared to plastoquinone (895.3 kcal/mol) to dock into the QB-binding site of the photosystem II complex of higher plants. Light, cryo-scanning, and transmission electron microscopy were utilized in an attempt to identify the cellular location of root exudate production. From the ultrastructure analysis, it is clear that exudate is being produced in the root hairs and being deposited between the plasmalemma and cell wall. The exact manufacturing and transport mechanism of the root exudate is still unclear. Studies were also conducted on sorgoleone's soil persistence and soil activity. Soil impregnated with sorgoleone had activity against a number of plant species. Recovery rates of sorgoleone-impregnated soil ranged from 85% after 1 h to 45% after 24 h. Growth reduction of 9 14-d-old weed species was observed with foliar applications of sorgoleone.

Type
Symposium
Copyright
Copyright © Weed Science Society of America 

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References

Literature Cited

Deisenhofer, J. and Michel, H. 1989. The photosynthetic reaction center from the purple bacterium Rhodopseudomonas viridis . Science 245: 14631473.Google Scholar
Duckett, C. M., Oparka, K. J., Prior, D. A. M., Dolan, L., and Roberts, K. 1994. Dye-coupling in the root epidermis of Arabidopsis is progressively reduced during development. Development 120: 32473255.Google Scholar
Duke, S. O., Scheffler, B. E., and Dayan, F. E. Strategies for using transgenes to produce allelopathic crops. Weed Technol. In press.Google Scholar
Einhellig, F. A. and Rasmussen, J. A. 1989. Prior cropping with grain sorghum inhibits weeds. J. Chem. Ecol. 15: 951960.Google Scholar
Einhellig, F. A., Rasmussen, J. A., Hejl, A. M., and Souza, I. F. 1993. Effects of root exudate sorgoleone on photosynthesis. J. Chem. Ecol. 19: 369375.Google Scholar
Einhellig, F. A. and Souza, I. F. 1992. Phytotoxicity of sorgoleone found in grain sorghum root exudates. J. Chem. Ecol. 18: 111.CrossRefGoogle ScholarPubMed
Gonzalez, V. M., Kazimir, J., Nimbal, C. I., Weston, L. A., and Cheniae, G. M. 1997. Inhibition of a photosystem II electron transfer reaction by the natural product sorgoleone. J. Agric. Food Chem. 45: 14151421.Google Scholar
Guenzi, W. D. and McCalla, I. N. 1966. Phenolic acids in oats, wheat, sorghum and corn residues and their phytotoxicity. Agron. J. 58: 303304.Google Scholar
Netzly, D. H. and Butler, L. G. 1986. Roots of sorghum exude hydrophobic droplets containing biologically active components. Crop Sci. 26: 775777.CrossRefGoogle Scholar
Nimbal, C. I., Pedersen, J. F., Yerkes, C. N., Weston, L. A., and Weller, S. C. 1996a. Phytotoxicity and distribution of sorgoleone in grain sorghum germplasm. J. Agric. Food Chem. 44: 13431347.Google Scholar
Nimbal, C. I., Yerkes, C. N., Weston, L. A., and Weller, S. C. 1996b. Herbicidal activity and site of action of the natural product sorgoleone. Pestic. Biochem. Physiol. 54: 7383.Google Scholar
Panasiuk, O., Bills, D. D., and Leather, G. R. 1986. Allelopathic influence of Sorghum bicolor on weeds during germination and early development of seedlings. J. Chem. Ecol. 12: 15331543.Google Scholar
Putnam, A. R. and DeFrank, J. 1983. Use of phytotoxic plant residues for selective weed control. Crop Prot. 2: 173181.CrossRefGoogle Scholar
Rice, E. L. 1984. Allelopathy. 2nd ed. Orlando, FL: Academic Press. 422 p.Google Scholar
Streibig, J. D., Dayan, F. E., Rimando, A. M., and Duke, S. O. 1999. Joint action of natural and synthetic photosystem II inhibitors. Pestic. Sci. 55: 137146.3.0.CO;2-D>CrossRefGoogle Scholar
Svensson, B., Etchebest, C., Tuffery, P., Van Kan, P., Smith, J., and Styring, S. 1996. A model for the photosystem II reaction center core including the structure of the primary donor P680. Biochemistry 35:14486.Google Scholar
Weston, L. A. 1996. Utilization of allelopathy for weed management in agroecosystems. Agron. J. 88: 860866.Google Scholar
Weston, L. A., Harmon, R., and Mueller, S. 1989. Allelopathic potential of sorghum-sudangrass hybrid (sudex). J. Chem. Ecol. 15: 18551865.Google Scholar