title: The allelochemical sorgoleone inhibits root H+-ATPase and water uptake.
abstract: Sorghum plants inhibit the growth of some adjacent species. Root exudates from grain sorghum (Sorghum bicolor), consisting primarily of the quinone sorgoleone, are phytotoxic to several plant species, yet the mechanisms of growth inhibition remain to be fully explained. Disruption of electron transport functions in isolated mitochondria and chloroplasts has been reported as one explanation for growth inhibition. In the studies reported here, however, soybean seedlings grown in nutrient solution with 10, 50, or 100 microM sorgoleone showed no disruption of photosynthesis, as measured by leaf fluorescence and oxygen evolution, yet their mean leaf surface area was less when grown in 100 microM sorgoleone. Furthermore, in the presence of these same concentrations of sorgoleone, decreased nutrient solution use by soybean seedlings and decreased H+-ATPase activity in corn root microsomal membranes were observed. This suggests that impairment of essential plant processes, such as solute and water uptake, driven by proton-pumping across the root cell plasmalemma should also be considered as a mechanism contributing to observed plant growth inhibition by sorgoleone.
authors.affiliation: Department of Biology, The University of South Dakota, Vermillion, South Dakota, USA. ahejl@ysd.k12.sd.us
authors.forename: Angela M
authors.initials: AM
authors.lastname: Hejli
authors.forename: Karen L
authors.initials: KL
authors.lastname: Koster
mesh_terms: D016227:Benzoquinones / Q000737:chemistry / Q000494:pharmacology*; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D002523:Edible Grain / Q000737:chemistry / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008055:Lipids / Q000737:chemistry / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D010675:Pheromones / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D013025:Glycine max / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D008055:Lipids; D010675:Pheromones; C113738:sorgoleone; D014867:Water; D006180:Proton-Translocating ATPases