Leaf manganese concentrations as a tool to assess belowground plant functioning in phosphorus-impoverished environments

Authors: LAMBERS, HANS - University Of Western Australia; WRIGHT, IAN - Macquarie University; PERERIA, CAIO GUILHERME - Massachusetts Institute Of Technology; BELLINGHAM, PETER - Landcare Research; BENTLEY, LISA - James Cook University; CERNUSAK, LUCAS - James Cook University; FOULDS, WILLIAM - Edith Cowan University (ECU); Gleason, Sean; GRAY, EMMA - Macquarie University; HAYES, PATRICK - Japanese International Research Center For Agricultural Sciences (JIRCAS) - Japan; KOOYMAN, ROB - Macquarie University; MALHI, YADVINDER - James Cook University; READ, JENNY - Monash University; RICHARDSON, SARAH - Landcare Research; SHANE, MICHAEL - University Of Western Australia; STAUDINGER, CHRISTIANA - University Of Western Australia; STOCK, WILLIAM - Edith Cowan University (ECU); SWARTS, NIGEL - University Of Tasmania; TURNER, BENJAMIN - Smithsonian Tropical Research; TURNER, JOSH - Nsw Office Of Environment And Heritage; WASAKI, JUN - University Of Hiroshima; WESTOBY, MARK - Macquarie University

Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2020
Publication Date: 9/9/2020
Citation: Lambers, H., Wright, I.J., Pereria, C., Bellingham, P., Bentley, L.P., Cernusak, L.A., Foulds, W., Gleason, S.M., Gray, E.F., Hayes, P.E., Kooyman, R., Malhi, Y., Read, J., Richardson, S.J., Shane, M.W., Staudinger, C., Stock, W.D., Swarts, N.D., Turner, B.L., Turner, J., Wasaki, J., Westoby, M. 2020. Leaf manganese concentrations as a tool to assess belowground plant functioning in phosphorus-impoverished environments. Plant and Soil. 461:43-61. https://doi.org/10.1007/s11104-020-04690-2.
DOI: https://doi.org/10.1007/s11104-020-04690-2

Interpretive Summary: Leaf manganese concentrations offer a method to screen for below-ground plant functional types related to P acquisition in nutrient-poor soils. In addition, it can be used in the selection of desirable crop genotypes and allows detailed investigation of how soil manganese (and phosphorus) uptake is achieved and regulated. We examined leaf manganese concentrations in the leaves of 727 angiosperm species across 66 sites in Australia and New Zealand. We found that leaf manganese concentration was a meaningful predictor of a specific type of mobilization mechanism (mobilization via a carboxylate root exudate). We therefore suggest that leaf manganese concentration may help to inform the evolutionary history of this below-ground trait, as well as serve a useful screening trait for crop selection.

Technical Abstract: Root-released carboxylates enhance the availability of manganese (Mn), which enters roots through transporters with low substrate specificity. Recently, leaf Mn concentration ([Mn]) was proposed as a signature for phosphorus (P)-mobilising carboxylates in the rhizosphere. Here we test whether leaf [Mn] provides a signature for belowground functional types related to P acquisition. In a suite of 727 species at 66 sites across Australia and New Zealand, leaf [Mn] was related to root functional type, and edaphic and climatic variables. To further assess the specific situations under which leaf [Mn] is a suitable proxy for rhizosphere carboxylate concentration, leaf [Mn] was studied along a strong gradient in water availability on one representative site. We found significantly lower leaf [Mn] in mycorrhizal plants than in plants with carboxylate-releasing root structures. Because leaf [Mn] varied with soil [Mn], soil pH and mean annual precipitation, comparisons of belowground functional types were applicable only within each site. Leaf [Mn] did not provide information about root functional types under seasonally water-logged conditions, which increase iron availability and thereby potentially interfere with Mn-uptake capacity. We conclude that leaf [Mn] provides valuable information on belowground functional types within a site, and discuss how this can lead to further discoveries.