UPTAKE AND TRANSLOCATION OF ALPHA-DIFLUOROMETHYLORNITHINE, A POLYAMINE BIOSYNTHESIS INHIBITOR, BY BARLEY SEEDLINGS - EFFECTS ON MILDEW INFECTION

Uptake of the polyamine biosynthesis inhibitor, α‐difluoromethylornithine (DFMO), by barley seedlings was examined. DFMO was taken up by intact roots and approached saturation at a rate of 780 mol m−12g−1d.wt. The uptake as a function of DFMO concentration in the external medium was biphasic, with Eadie‐Hofstee transformations giving Km values for system 1 uptake of 1.61 mol m−3and for system 2 uptake of 53.31 mol m−3. DFMO uptake was reduced in darkness and was greatly influenced by transpiration rate. The inhibitor was taken up from host cells by the powdery mildew fungus, Erysiphe graminis f.sp. hordei Marchal, and DFMO fed to roots, or to excised leaves at different times after inoculation, gave substantial control of mildew infection. Copyright © 1990, Wiley Blackwell. All rights reserved