Transport of Xenobiotics in Higher Plants IV. Amobility of the Acidic Compounds Bromoxynil and Pentachlorophenol

摘要: Summary In contrast to the conclusion that acidic compounds with p Ka smaller than 7 are phloem- or ambimobile, on basis of results Sinapis translocation test phenolic derivatives 2,5-dibromo-4-hydroxybenzonitrile (bromoxynil, K a = 4.1) and pentachlorophenol (PCP, 4.5) have be classified as amobile. Amounts up 10 -4 M bromoxynil -5 PCP do not any poisonous effect phloem transport in seedlings. On other hand sucrose uptake into Cyclamen conducting tissue was affected if concentrations exceeded -6 M. Uptake both by isolated investigated nontoxic concentration range found accomplished diffusion. While absorption independent proton external solution, exhibits an optimum at H 4.0 inhibited carbonyl cyanide m-chlorophenylhydrazone dinitrophenol. Consequently, retention symplast is determined ion trapping. From experiments frozen-thawed cotyledons well from efflux studies it concluded unspecifically bound several cellular constituents (cutin, lignin, membrane lipids). Binding higher bromoxynil. The same applies adsorption when compared tissue. Nevertheless, cases prevents quantitative transfer to, in, long distance streams, although even assumed potentially translocable due its