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

Lambers, Hans, Wright, Ian J., Pereira, Caio Guilherme, Bellingham, Peter J., Bentley, Lisa Patrick, Boonman, Alex, Cernusak, Lucas A., Foulds, William, Gleason, Sean M., Gray, Emma F., Hayes, Patrick E., Kooyman, Robert M., Malhi, Yadvinder, Richardson, Sarah J., Shane, Michael W., Staudinger, Christiana, Stock, William D., Swarts, Nigel D., Turner, Benjamin L., Turner, John, Veneklaas, Erik J., Wasaki, Jun, Westoby, Mark, and Xu, Yanggui (2021) Leaf manganese concentrations as a tool to assess belowground plant functioning in phosphorus-impoverished environments. Plant and Soil: international journal on plant-soil relationships, 461. pp. 43-61.

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Abstract

Background and aims

Root-released carboxylates enhance the availability of manganese (Mn), which enters roots through transporters with low substrate specificity. Leaf Mn concentration ([Mn]) has been proposed as a signature for phosphorus (P)-mobilising carboxylates in the rhizosphere. Here we test whether leaf [Mn] provides a signature for root functional types related to P acquisition.

Methods

Across 727 species at 66 sites in Australia and New Zealand, we measured leaf [Mn] as related to root functional type, while also considering soil and climate variables. To further assess the specific situations under which leaf [Mn] is a suitable proxy for rhizosphere carboxylate concentration, we studied leaf [Mn] along a strong gradient in water availability on one representative site. In addition, we focused on two systems where a species produced unexpected results.

Results

Controlling for background site-specific variation in leaf [Mn] with soil pH and mean annual precipitation, we established that mycorrhizal species have significantly lower leaf [Mn] than non-mycorrhizal species with carboxylate-releasing root structures, e.g., cluster roots. In exception to the general tendency, leaf [Mn] did not provide information about root functional types under seasonally waterlogged conditions, which increase iron availability and thereby interfere with Mn-uptake capacity. Two further exceptions were scrutinised, leading to the conclusion that they were 'anomalous' in not functioning like typical species in their families, as expected according to the literature.

Conclusions

Leaf [Mn] variation provides considerable insights on differences in belowground functioning among co-occurring species. Using this approach, we concluded that, within typical mycorrhizal families, some species actually depend on a carboxylate-releasing P-mobilising strategy. Likewise, within families that are known to produce carboxylate-releasing cluster roots, some do not produce functional cluster roots when mature. An analysis of leaf [Mn] can alert us to such 'anomalous' species.

Item ID: 64697
Item Type: Article (Research - C1)
ISSN: 0032-079X
Keywords: Belowground functional types, Carboxylates, Cluster roots, Leaf manganese concentration, Mycorrhizal, Non-mycorrhizal, Phosphorus acquisition, Rhizosphere, Soil pH
Copyright Information: © Springer Nature Switzerland AG 2020
Funders: Australian Research Council (ARC), Ministry of Business, Innovation and Employment: Science and Innovation Group (MBIE), Austrian Science Fund (FWF)
Projects and Grants: ARC DP130100005, ARC DP120103284, FWF Erwin-Schrödinger Fellowship
Date Deposited: 21 Oct 2020 08:04
FoR Codes: 31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310806 Plant physiology @ 100%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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