Browsing by Author "Fernando, DR"

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    Characterization of foliar manganese (Mn) in Mn (hyper)accumulators using x-ray absorption spectroscopy
    (Wiley-Blackwell, 2010-12-01) Fernando, DR; Mizuno, T; Woodrow, IE; Baker, AJM; Collins, RN
    Plant hyperaccumulation of the essential nutrient manganese (Mn) is a rare phenomenon most evident in the Western Pacific region, and differs from hyperaccumulation of other elements. Mn hyperaccumulators employ a variety of species-dependent spatial distribution patterns in sequestering excess foliar Mn, including primary sequestration in both nonphotosynthetic and photosynthetic tissues. This investigation employed synchrotron X-ray absorption spectroscopy (XAS) in a comparative study of Mn (hyper)accumulators, to elucidate in situ the chemical form(s) of foliar Mn in seven woody species from Australia, New Caledonia and Japan. Foliar Mn was found to predominate as Mn(II) in all samples, with strong evidence of the role of carboxylic acids, such as malate or citrate, as complexing ligands. Overall, the X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS) data appeared weighted against previous observations that oxalate binds excess Mn in Mn-(hyper)accumulating species. © 2010, Wiley-Blackwell.
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    Multiple metal accumulation within a manganese-specific genus
    (Botanical Society of America, 2013-04) Fernando, DR; Marshall, AT; Forster, PI; Hoebee, SE; Siegele, R
    Premise of the study: Plants that strongly accumulate metals may be practically beneficial, and also serve as novel resources for increasing fundamental understanding of plant biology. Australian Gossia (Myrtaceae) species are delineated by a conspicuous affinity for the heavy metal manganese (Mn), which is a micronutrient crucial to photosynthesis. This genus includes several Mn hyperaccumulators such as G. bidwillii. Unusually, in G. bidwillii foliar Mn is most highly concentrated in photosynthetic cells, an observation thus far restricted to foliar-Mn accumulation in Mn hyperaccumulators. Recent discovery that several of these Gossia species accumulate other metals in addition to Mn will enable investigation as to whether primary sequestration of metals in photosynthetic tissues is restricted to Mn. Methods: Gossia species known to accumulate nickel (Ni) or aluminum (Al) in addition to Mn were sampled in the field. Complementary proton- and electron-probe data were combined to evaluate in vivo microdistribution patterns of excessively accumulated foliar metals. • Key results: It was discovered that in addition to Mn and Ni, Gossia fragrantissima accumulated foliar zinc (Zn) and cobalt (Co), with Mn, Ni, and Co most highly localized in mesophyll cells and Zn primarily located in the upper epidermis. In G. hillii, Mn and Al were highly concentrated in the palisade and epidermis, respectively. Conclusions: This investigation provides evidence that the primary disposal of excess foliar metals in photosynthetic cells is not exclusive to Mn. It offers rare intrageneric perspective on metal compartmentation, pointing to significant variation among tonoplastal metal transporters associated with detoxification. © 2013, Botanical Society of America.