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Proc Natl Acad Sci U S A. 2015 Aug 4;112(31):9781-6. doi: 10.1073/pnas.1413762112. Epub 2015 Jul 21.

A role for the mevalonate pathway in early plant symbiotic signaling.

Author information

1
Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706; venkateshwam@uwplatt.edu.
2
Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706;
3
Laboratory of Plant-Microbe Interactions, Institut National de Recherche Agronomique (UMR 441), Centre Nationale de Recherche Scientifique (UMR 2594), F-31320 Castanet-Tolosan, France;
4
Department of Life Sciences and Systems Biology, University of Torino, 10125 Torino, Italy;
5
Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706;
6
Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706;
7
Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706.

Abstract

Rhizobia and arbuscular mycorrhizal fungi produce signals that are perceived by host legume receptors at the plasma membrane and trigger sustained oscillations of the nuclear and perinuclear Ca(2+) concentration (Ca(2+) spiking), which in turn leads to gene expression and downstream symbiotic responses. The activation of Ca(2+) spiking requires the plasma membrane-localized receptor-like kinase Does not Make Infections 2 (DMI2) as well as the nuclear cation channel DMI1. A key enzyme regulating the mevalonate (MVA) pathway, 3-Hydroxy-3-Methylglutaryl CoA Reductase 1 (HMGR1), interacts with DMI2 and is required for the legume-rhizobium symbiosis. Here, we show that HMGR1 is required to initiate Ca(2+) spiking and symbiotic gene expression in Medicago truncatula roots in response to rhizobial and arbuscular mycorrhizal fungal signals. Furthermore, MVA, the direct product of HMGR1 activity, is sufficient to induce nuclear-associated Ca(2+) spiking and symbiotic gene expression in both wild-type plants and dmi2 mutants, but interestingly not in dmi1 mutants. Finally, MVA induced Ca(2+) spiking in Human Embryonic Kidney 293 cells expressing DMI1. This demonstrates that the nuclear cation channel DMI1 is sufficient to support MVA-induced Ca(2+) spiking in this heterologous system.

KEYWORDS:

HMG-CoA reductase; arbuscular mycorrhization; calcium signaling; legume nodulation; mevalonate

PMID:
26199419
PMCID:
PMC4534228
DOI:
10.1073/pnas.1413762112
[Indexed for MEDLINE]
Free PMC Article

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