Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2003
Publication Date: 1/26/2004
Citation: Yang, X., Owens, T.G., Scheffler, B.E., Weston, L.A. Manipulation of root hair development and Sorgoleone production in sorghum seedlings. Journal of Chemical Ecology. 2004. V. 30(1). P. 199-213. Interpretive Summary: By nature, sorghum is an allelopathic crop in that it suppresses the growth of nearby weeds. This weed suppression is in part due to the release of a compound called sorgoleone, which is exuded into the soil by the root hairs. To better understand how sorgoleone is produced, this research investigated various growing conditions and their effect on sorgoleone production. Certain growing conditions had a dramatic effect on root hair production and this greatly influenced sorgoleone production. In general, roots grown under a mist condition produced significant levels of sorgoleone, while seedlings grown on a mat with running water did not produce root hairs or sorgoleone. The results show that the production of root hairs and thus sorgoleone are dependent on ethylene production.
Technical Abstract: Sorghum (Sorghum bicolor) roots exude a potent bioherbicide - sorgoleone. Previous work in our laboratory indicates that sorgoleone is produced in living root hairs. We have developed a mist system that resulted in abundant production of root hairs exuding sorgoleone and a mat system that significantly inhibited root hair development and consequently sorgoleone production. Applying Ag+ (an ethylene action inhibitor) at 1.2 mM to the seedlings grown in the mist system also significantly inhibited root hair formation and elongation. Hypoxic conditions in the mist system did not result in the inhibition of root hair growth as compared to the standard air atmosphere (20.8% 02). Applying ethephon (an ethylene-releasing agent) at 0.031 mM to the roots of seedlings grown in the mat system with water running at 1 ml/min reversed the inhibition of root hair development by water movement. These results indicate that either water movement or ethylene can be utilized to manipulate root hair development and sorgoleone production in sorghum seedlings. It is hypothesized that water movement reduced the local ethylene concentration on the root surface and consequently inhibited root hair development of sorghum seedlings grown in the mat system.