Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: December 11, 2009
Publication Date: December 30, 2009
Citation: Centofanti, T., Fellet, G., Green, C.E., Chaney, R.L. 2009. NiO (bunsenite) is not available to Alyssum species. BARC Poster Day. 319:219-223.
Some species of the genus Alyssum are capable of accumulating up to 30 g kg-1 DW Ni in their leaves when grown on serpentine soils where these species are endemic. The unique ability of Alyssum species to hyperaccumulate high concentration of Ni stimulated basic research toward a better understanding of the physiology and biochemistry to improve metal uptake efficiency. Ni hyperaccumulators can be used in phytomining which is an economically sound alternative way of producing Ni ore.
One of the mysteries about Ni hyperaccumulator species is how they are able to uptake Ni from Ni mineralized or contaminated soils very effectively (100 times higher than crop plants) although they absorb Ni from the same labile forms in soils as normal plant species can access.
As part of our research on Ni hyperaccumulation by plants, we conducted an experiment to determine if the Ni-hyperaccumulator Alyssum corsicum can absorb Ni from the kinetically inert crystalline mineral NiO(s)(bunsenite).
A. corsicum and A. montanum plants were grown for 30 days in a serpentine Hoagland solution with 2 mM Mg and 1 mM Ca to simulate serpentine soil solutions. NiO was provided at 0 or 0.1 g L-1 (1.34 mmol L-1) as reagent grade NiO particles <1 µm diameter, continuously mixed by aeration. A. corsicum and A. montanum shoots contained 19.4 and 5.2 mg Ni kg-1 DW with NiO, and 3.0 and 1.1 mg Ni kg-1 DW shoots, respectively in the control treatment. Roots were coated with the NiO particles and contained 3-5% Ni at harvest.
Considering that A. corsicum naturally translocates Ni to the shoots reaching 20 g Ni kg-1 dry weight or higher depending on the Ni availability, the Ni accumulated by the plants in this experiment is very low. A. corsicum is not capable of dissolving and hyperaccumulating Ni from NiO.
Additional experiments are ongoing to test whether Alyssum roots can access Ni from different Ni compounds that are relatively insoluble at pH 7. Other experiments examined the release of Ni from the seeds during germination, and use of X-ray Spectroscopy to measure the distribution of Ni within Alyssum seeds (nearly entirely within the embryo).