Localization of Atrazine in Corn (Zea mays), Oat (Avena sativa), and Kidney Bean (Phaseolus vulgaris) Leaf Cells

Corn ( Zea mays L. ‘DeKalb 640′), kidney beans ( Phaseolus vulgaris L. ‘Light red’) and oats ( Avena sativa L. ‘Kanota’) were grown in solution culture and the roots exposed to radioactively labeled atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)- s -triazine]. The radioactivity from 3 H-atrazine, or its metabolites, was located in microautoradiographs of corn leaf sections, almost exclusively at the perimeter of the vascular bundles, and was primarily confined to the cell walls and intercellular spaces, with no activity associated with subcellular organelles. Radioactivity from 3 H-atrazine in oat leaf section microautoradiographs was primarily associated with the chloroplasts, with no evidence of radioactivity specifically associated with other subcellular organelles. Sucrose density gradient centrifugation of homogenized leaf tissue following exposure of the plants to 14 C-atrazine showed that most of the radioactivity was associated with the light cell fragments and cytoplasm for the test species. There was no accumulation of 14 C-activity in any of the heavier subcellular organelles from corn leaf cells. A peak of radioactivity was associated with the chloroplast fraction from oat and kidney bean leaves.