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poisonous plants--nickel hyperaccumulators
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Subject: poisonous plants--nickel hyperaccumulators
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From: fzscott@rocky.ucdavis.edu (Scott Martens)
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Date: 7 Aug 1995 21:49:53 GMT
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Article: 25303 of sci.bio
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Newsgroups: sci.bio
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Organization: University of California, Davis
There are relatively few plants that accumulate sufficient levels of
elements from soil to render themselves acutely toxic to herbivores.
Nickel "hyperaccumulators", capable of accumulating more than 1000 ppm Ni,
however, can do so. There are only about 200 or so nickel
hyperaccumulating species known, but they occur nearly everywhere Ni-rich,
serpentine-derived soils occur around the world. We (Martens and Boyd,
1994) have shown that a Californian nickel-hyperaccumulator, Streptanthus
polygaloides (Brassicaceae), is acutely toxic to potential herbivores
(lepidopteran larvae, as well as grasshoppers), and demonstrated similar
results for Thlaspi montanum (Brassicaceae) (Boyd and Martens, 1994). We
have also been able to show that fungal and bacterial pathogens are
deterred by nickel hyperaccumulation (Boyd et al., 1994). Large, mobile
herbivores might circumvent the nickel defense simply by consuming a
mixed diet, but many bacterial and fungal pathogens, and insect
herbivores, spend all (or nearly all) of their lives on a single host
plant. Nickel hyperaccumulation seems to be an effective defense because
of its high lethality, apparent low cost to the plant, and broad spectrum
of toxicity. For more info you might check out the papers below:
Martens, Scott N. and Robert S. Boyd. 1994. The ecological significance
of nickel hyperaccumulation: a plant chemical defense. Oecologia
98:379-384.
Boyd, Robert S. and Scott N. Martens. 1994. Nickel hyperaccumulated by
Thlaspi montanum var. montanum is acutely toxic to an insect herbivore.
Oikos 70:21-25.
Boyd, Robert S., Joe J. Shaw, and Scott N. Martens. 1994. Nickel
hyperaccumulation defends Streptanthus polygaloides (Brassicaceae)
against pathogens. American Journal of Botany 81:294-300.
Scott N. Martens
Department of Land, Air, and Water Resources
University of California, Davis
Davis, CA 95616
snmartens@ucdavis.edu