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


Thomas D. Alcock

Catherine L. Thomas


Paula Pongrac

Christopher Moore

Guilhem Reyt


Mitja Kelemen

Rory Hayden

Lolita Wilson

Pauline Stephenson


Judith A. Irwin

John P. Hammond

Graham J. King

David E. Salt

Senior Research Fellow

Philip J. White


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.


Alcock, T. D., Thomas, C. L., Ó Lochlainn, S., Pongrac, P., Wilson, M., Moore, C., …Broadley, M. R. (2021). Magnesium and calcium overaccumulate in the leaves of a schengen3 mutant of Brassica rapa. Plant Physiology, 186(3), 1616-1631.

Journal Article Type Article
Acceptance Date Mar 12, 2021
Online Publication Date Apr 8, 2021
Publication Date Jul 1, 2021
Deposit Date Apr 27, 2021
Publicly Available Date Apr 27, 2021
Journal Plant Physiology
Print ISSN 0032-0889
Electronic ISSN 1532-2548
Publisher American Society of Plant Biologists
Peer Reviewed Peer Reviewed
Volume 186
Issue 3
Pages 1616-1631
Keywords Plant Science; Genetics; Physiology
Public URL
Publisher URL


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