Magnesium and calcium overaccumulate in the leaves of a schengen3 mutant of Brassica rapa

A - Papers appearing in refereed journals

Alcock, T. D., Thomas, C. L., Lochlainn, S. O., Pongrac, P., Wilson, M., Moore, C., Reyt, G., Vogel-Mikus, K., Kelemen, M., Hayden, R., Wilson, L., Stephenson, P., Ostergaard, L., Irwin, J. A., Hammond, J. P., King, G. J., Salt, D. E., Graham, N. S., White, P. J. and Broadley, M. R. 2021. Magnesium and calcium overaccumulate in the leaves of a schengen3 mutant of Brassica rapa. Plant Physiology. 186 (3), pp. 1616-1631. https://doi.org/10.1093/plphys/kiab150

AuthorsAlcock, T. D., Thomas, C. L., Lochlainn, S. O., Pongrac, P., Wilson, M., Moore, C., Reyt, G., Vogel-Mikus, K., Kelemen, M., Hayden, R., Wilson, L., Stephenson, P., Ostergaard, L., Irwin, J. A., Hammond, J. P., King, G. J., Salt, D. E., Graham, N. S., White, P. J. and Broadley, M. R.
Abstract

Magnesium (Mg) and calcium (Ca) are essential mineral nutrients poorly supplied in many human food systems. In grazing livestock, Mg and Ca deficiencies are costly welfare issues. Here, we report a Brassica rapa loss-of-function schengen3 (sgn3) mutant, braA.sgn3.a-1, which accumulates twice as much Mg and a third more Ca in its leaves. We mapped braA.sgn3.a to a single recessive locus using a forward ionomic screen of chemically mutagenized lines with subsequent backcrossing and linked-read sequencing of second back-crossed, second filial generation (BC2F2) segregants. Confocal imaging revealed a disrupted root endodermal diffusion barrier, consistent with SGN3 encoding a receptor-like kinase required for normal formation of Casparian strips, as reported in thale cress (Arabidopsis thaliana). Analysis of the spatial distribution of elements showed elevated extracellular Mg concentrations in leaves of braA.sgn3.a-1, hypothesized to result from preferential export of excessive Mg from cells to ensure suitable cellular concentrations. This work confirms a conserved role of SGN3 in controlling nutrient homeostasis in B. rapa, and reveals mechanisms by which plants are able to deal with perturbed shoot element concentrations resulting from a "leaky" root endodermal barrier. Characterization of variation in leaf Mg and Ca accumulation across a mutagenized population of B. rapa shows promise for using such populations in breeding programs to increase edible concentrations of essential human and animal nutrients.

KeywordsShoot calcium; Micro-pixe; Genomics; Ionomics; Elements; Barrier; Crops; Loci
Year of Publication2021
JournalPlant Physiology
Journal citation186 (3), pp. 1616-1631
Digital Object Identifier (DOI)https://doi.org/10.1093/plphys/kiab150
Web address (URL)https://academic.oup.com/plphys/article/186/3/1616/6217901
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeBBSSE200613215
Publisher's version
Supplemental file
Output statusPublished
Publication dates
Online08 Apr 2021
Publication process dates
Accepted12 Mar 2021
PublisherAmerican Society of Plant Biologists (ASPB)
ISSN0032-0889

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