Mechanisms of trichome-specific Mn accumulation and toxicity in the Ni hyperaccumulator Alyssum murale

David H. McNear, Joseph V. Kupper

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Background and aims: Mechanisms of Mn accumulation and toxicity in and around trichomes on the Ni hyperaccumulator Alyssum murale were investigated. Methods: Plants were grown aeroponically with variable amounts of Mn and Ni. Total metals were determined and electron microprobe analysis (EMPA) and synchrotron-based micro x-ray fluorescence (μ-SXRF) spectroscopy were used to evaluate metal distribution. Synchrotron techniques (μ-XANES, μ-EXAFS) along with infrared spectroscopy (DRIFT) were used to determine Mn speciation. Results: At lower Mn concentrations or when grown together with Ni, Mn is confined to the trichome basal compartment in the +2 oxidation state in a complex with phosphate. At tissue concentrations >1,150 μg g-1 Mn-rich lesions develop around some trichomes in which greater amounts of Mn 3+ is found. Conclusions: Mn is preferentially stored in trichomes on the plant surface which at higher concentrations enters the cell wall or apoplastic space of neighboring cells resulting in the formation of brown reaction products and oxidized Mn species. We propose a mechanism by which lesion formation and oxidized Mn species around some trichomes is possibly due to induction of the peroxidase system by excess Mn, triggering the accumulation of toxic phenoxy radicals and Mn3+.

Original languageEnglish
Pages (from-to)407-422
Number of pages16
JournalPlant and Soil
Issue number1-2
StatePublished - Apr 2014

Bibliographical note

Funding Information:
Acknowledgments The authors would like to thank Dr. Jason Unrine for ICP-MS analysis of total metal concentrations, the environmental soil chemistry research group of Dr. Donald Sparks for the Mn standard spectra and Matthew Marcus at beamline 10.3.2 for advice on Mn fitting. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.


  • Alyssum murale
  • Hyperaccumulation
  • Manganese (Mn)
  • Nickel (Ni)
  • Synchrotron x-ray absorption fine structure spectroscopy (XAFS)
  • Trichome

ASJC Scopus subject areas

  • Soil Science
  • Plant Science


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