Translocation and metabolism of radiolabeled RPA 201772 was studied in Setaria faberi. Tissue-killing heat girdles were used to determine the extent of RPA 201772 transport in the apoplast and symplast. In leaf uptake studies, girdling was performed above and below the treated area on the leaf. In root uptake studies, girdling was performed on the stem just above the crown. Girdling restricted translocation of 14C following both the root and leaf applications. However, translocation occurred past the girdles suggesting that both the symplast and apoplast are involved in translocation of 14C from RPA 201772. Translocation of 14C out of the treated leaf was reduced 85% with a girdle below the 14C spotting area. In root metabolism studies, 27, 40, and 33% of recovered 14C were identified as parent RPA 201772, diketonitrile, and other metabolites, respectively, 24 h after treatment (HAT). Conversion from parent RPA 201772 to diketonitrile was more extensive in leaf tissue than in roots with 10, 68, and 22% of recovered 14C identified as parent RPA 201772, diketonitrile, and other metabolites, respectively, in the treated area of the leaf 24 HAT. Metabolite analysis demonstrated RPA 201772 is mobile in both the apoplast and symplast.
Nomenclature: RPA 201772 (5-cyclopropylisoxazol-4-yl 2-mesyl-4-trifluoromethylphenol ketone); Setaria faberi Herrm. SETFA; giant foxtail.