Comparative systemic translocation of several xenobiotics and sucrose

The systemic movement of several xenobiotics was compared in soybean and barley. The more symplastic compounds were also compared to the movement of sucrose. The uptake and efflux from potato tuber tissue was studied and related to the in vivo translocation patterns. The patterns of translocation ranged from primarily apoplastic to ambimobile to symplastic. When the percentage of xenobiotic available for translocation was evaluated there were major differences in patterns of translocation, between plant genera. In barley fenapanil, fenarimol, and oxamyl exhibited primarily apoplastic transport while all three were more ambimobile in soybean. Basipetal transport of oxamyl was 4.2% in barley compared to 30.8% in soybean. Basipetal translocation of benomyl remained very low at 3.0 and 4.1% in barley and soybean, respectively, while sucrose was about 60% in both species. Glyphosate and sucrose were translocated in a similar pattern. The transport of 2,4-D was primarily symplastic, however, retention in the tissue appeared to limit the rate of movement when compared to sucrose. Uptake and efflux of fenapanil, fenarimol, and 2,4-D illustrated the possible role that cellular binding or partitioning may play in systemic translocation. In conjunction with the uptake and efflux, and systemic movement in plants, the octanol/water partition coefficients, log P, for fenarimol and fenapanil, 0.67 and ?0.03, respectively, are correlated with the possible role of cellular binding or partitioning in the systemic movement of xenobiotics.