Department of Environmental Sciences, University of Helsinki, Finland.
Dose Response. 2010 Jun 25;9(1):130-43. doi: 10.2203/dose-response.09-045.Sinkkonen.
During the last decade, the paradigm that low toxicant doses often have stimulatory effects on plants has become widely accepted. At the same time, low toxicant doses of metal salts have been observed to inhibit the growth of the most vigorous seedlings of a population in vitro, although mean plant size has remained unaffected. We hypothesized that this kind of selective low-dose toxicity is not restricted to inorganic contaminants. We exposed annual plants (baby's breath Gypsophila elegans, purslane Portulaca oleracea, and duckweed Lemna minor) to 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-γ-2-benzopyran (HHCB) and 4-tert-octylphenol and lead acetate. As compared to unexposed G. elegans roots, 4-tert-octylphenol did not affect the mean root size of all seedlings, but it reduced the average length of roots longer than the 98(th) percentile. A comparable response was found in case of G. elegans roots treated with lead acetate beyond the 90(th) percentile. The average size of roots beyond the 90(th) percentile was decreased also when L. minor was exposed to lead acetate though the means of all roots were constant. P. oleracea seemed to be insensitive to selective toxicity. We conclude that selective toxicity at low doses should be considered in parallel with hormesis.
在过去的十年中，低毒物剂量通常对植物具有刺激作用的范式已被广泛接受。与此同时，尽管平均植物大小不受影响，但观察到金属盐的低毒物剂量在体外抑制了种群中最旺盛幼苗的生长。我们假设这种选择性低剂量毒性不仅限于无机污染物。我们将一年生植物（满天星 Gypsophila elegans、马齿苋 Portulaca oleracea 和浮萍 Lemna minor）暴露于 1,3,4,6,7,8-六氢-4,6,6,7,8,8-六甲基环戊二烯并[g]-2-苯并吡喃（HHCB）和 4-叔辛基苯酚和醋酸铅中。与未暴露的 G. elegans 根相比，4-叔辛基苯酚不影响所有幼苗的平均根大小，但它减少了长于第 98（百分位）的根的平均长度。在 G. elegans 根处理铅超过第 90（百分位）的情况下，也发现了类似的反应。当 L. minor 暴露于铅超过第 90（百分位）时，第 90（百分位）以上的根的平均大小也减少了，尽管所有根的平均值保持不变。P. oleracea 似乎对选择性毒性不敏感。我们得出结论，低剂量的选择性毒性应与激素作用一起考虑。
