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Mol Plant. 2018 Apr 2;11(4):553-567. doi: 10.1016/j.molp.2017.12.015. Epub 2017 Dec 27.

Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation.

Author information

1
Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, PO Box 7080, 750 07 Uppsala, Sweden.
2
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden.
3
Umeå Plant Science Centre, Umeå University, 90187 Umeå, Sweden; Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, 14476 Potsdam, Germany.
4
Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany ASCR and Palacký University, 783 71 Olomouc, Czech Republic.
5
Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences (SLU), 90183 Umeå, Sweden; Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany ASCR and Palacký University, 783 71 Olomouc, Czech Republic.
6
The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK.
7
Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences (SLU) and Linnean Center for Plant Biology, PO Box 7080, 750 07 Uppsala, Sweden. Electronic address: daniel.hofius@slu.se.

Abstract

Brassinosteroid (BR) hormone signaling controls multiple processes during plant growth and development and is initiated at the plasma membrane through the receptor kinase BRASSINOSTEROID INSENSITIVE1 (BRI1) together with co-receptors such as BRI1-ASSOCIATED RECEPTOR KINASE1 (BAK1). BRI1 abundance is regulated by endosomal recycling and vacuolar targeting, but the role of vacuole-related proteins in BR receptor dynamics and BR responses remains elusive. Here, we show that the absence of two DUF300 domain-containing tonoplast proteins, LAZARUS1 (LAZ1) and LAZ1 HOMOLOG1 (LAZ1H1), causes vacuole morphology defects, growth inhibition, and constitutive activation of BR signaling. Intriguingly, tonoplast accumulation of BAK1 was substantially increased and appeared causally linked to enhanced BRI1 trafficking and degradation in laz1 laz1h1 plants. Since unrelated vacuole mutants exhibited normal BR responses, our findings indicate that DUF300 proteins play distinct roles in the regulation of BR signaling by maintaining vacuole integrity required to balance subcellular BAK1 pools and BR receptor distribution.

KEYWORDS:

Arabidopsis; DUF300 proteins; brassinosteroid signaling; tonoplast; vacuole integrity

PMID:
29288738
DOI:
10.1016/j.molp.2017.12.015

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