Merck

Opinion: nickel and urease in plants: still many knowledge gaps.

Plant science : an international journal of experimental plant biology (2012-12-26)
Joe C Polacco, Paulo Mazzafera, Tiago Tezotto
ABSTRACT

We propose experimental strategies to expand our understanding of the role of Ni in plants, beyond the Ni-metallocenter of urease, still the only identified Ni-containing plant enzyme. While Ni has been considered an essential mineral for plants there is a clear lack of knowledge of its involvement in metabolic steps except the urease-catalyzed conversion of urea to ammonia and bicarbonate. We argue that urease (and hence, Ni) plays an important role in optimal N-use efficiency under various N regimes by recycling urea-N, which is generated endogenously exclusively from arginase action on arginine. We further suggest that urease and arginase may connect different metabolic compartments under stress situations, and therefore may be involved in stress tolerance. To determine possible non-urease roles of Ni we call for experimental manipulation of both Ni and N availability in urease-negative mutants. Plant ureases have been shown to have defense roles, distinct from their ureolytic activity, and we call for investigation of whether Ni helps maintain a urease conformation or stability for these non-ureolytic defense roles. The beneficial effects of Ni at upper concentration limits have not been fully examined. We posit a "Ni strategy" of plants whose growth/performance is stimulated by unusual amounts of soil Ni, for defense and/or for maximal N-use efficiency. While we know little about Ni and urease roles in N metabolism and defense, virtually nothing is known about Ni roles in plant-microbial 'consortia.' And, much of what we know of Ni and urease is limited to only a few plants, e.g. soybean, potato and Arabidopsis, and we suggest studies vigorously extended to other plants.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Nickel, rod, diam. 6.35 mm, ≥99.99% trace metals basis
Sigma-Aldrich
Nickel, powder, <50 μm, 99.7% trace metals basis
Sigma-Aldrich
Nickel, wire, diam. 0.5 mm, ≥99.9% trace metals basis
Sigma-Aldrich
Nickel, foil, thickness 0.1 mm, 99.98% trace metals basis
Sigma-Aldrich
Nickel, foil, thickness 0.5 mm, 99.98% trace metals basis
Nickel, foil, 50mm disks, thickness 0.01mm, 99.95%
Nickel, foil, not light tested, 300x300mm, thickness 0.0125mm, 99.9%
Nickel, foil, light tested, 150x150mm, thickness 0.025mm, annealed, 99%
Nickel, foil, light tested, 50x50mm, thickness 0.01mm, 99.95%
Nickel, foil, light tested, 100x100mm, thickness 0.075mm, annealed, 99%
Nickel, foil, not light tested, 25x25mm, thickness 0.00075mm, temporary acrylic support, 99.95%
Nickel, foil, not light tested, 100x100mm, thickness 0.008mm, 99.95%
Nickel, rod, 1000mm, diameter 12.7mm, 99.98%
Nickel, foil, 25x25mm, thickness 0.25mm, annealed, 99%
Nickel, foil, not light tested, 300x300mm, thickness 0.0125mm, annealed, 99%
Nickel, tube, 500mm, outside diameter 1.0mm, inside diameter 0.8mm, wall thickness 0.1mm, hard, 99.5%
Nickel, pellets, 20g, max. size 20mm, 99.99+%
Nickel, foil, 25mm disks, thickness 0.25mm, annealed, 99%
Nickel, foil, 0.5m coil, thickness 0.125mm, annealed, 99%
Nickel, foil, 0.5m coil, thickness 0.005mm, as rolled, 99.9%
Nickel, foil, not light tested, 98x100mm, thickness 0.005mm, as rolled, 99.9%
Nickel, mesh, 65x65mm, nominal aperture 0.34mm, thickness 0.025mm, wire diameter 0.041mm, 70 wires/inch, open area 80%, electro-formed mesh, 99.9%
Nickel, tube, 500mm, outside diameter 2.5mm, inside diameter 2mm, wall thickness 0.25mm, hard, 99.5%
Nickel, rod, 1000mm, diameter 2.0mm, 99.99+%
Nickel, mesh, 240x240mm, nominal aperture 0.43mm, thickness 0.004mm, wire diameter 0.067mm, 51 wires/inch, open area 75%, electro-formed mesh, 99.9%
Nickel, foil, 2m coil, thickness 0.5mm, annealed, 99.98%
Nickel, foil, 50x50mm, thickness 2.0mm, annealed, 99%
Nickel, foil, 50x50mm, thickness 0.25mm, as rolled, 99.99+%
Nickel, foil, 50mm disks, thickness 0.0075mm, 99.9%
Nickel, foil, 50mm disks, thickness 0.025mm, annealed, 99%