Maize cytokinin dehydrogenase isozymes are predominantly localized to the vacuole

Zalabák, David, Johnová, Patricie, Plíhal, Ondřej, Šenková, Karolina, Šamajová, Olga, Jiskrová, Eva, Novák, Ondřej, Jackson, David, Mohanty, Amitabh, Galuszka, Petr (March 2016) Maize cytokinin dehydrogenase isozymes are predominantly localized to the vacuole. Plant Physiology and Biochemistry, 104. pp. 114-124. ISSN 0981-9428

URL: http://www.ncbi.nlm.nih.gov/pubmed/27031423
DOI: 10.1016/j.plaphy.2016.03.013

Abstract

The maize genome encompasses 13 genes encoding for cytokinin dehydrogenase isozymes (CKXs). These enzymes are responsible for irreversible degradation of cytokinin plant hormones and thus, contribute regulating their levels. Here, we focus on the unique aspect of CKXs: their diverse subcellular distribution, important in regulating cytokinin homeostasis. Maize CKXs were tagged with green fluorescent protein (GFP) and transiently expressed in maize protoplasts. Most of the isoforms, namely ZmCKX1, ZmCKX2, ZmCKX4a, ZmCKX5, ZmCKX6, ZmCKX8, ZmCKX9, and ZmCKX12, were associated with endoplasmic reticulum (ER) several hours after transformation. GFP-fused CKXs were observed to accumulate in putative prevacuolar compartments. To gain more information about the spatiotemporal localization of the above isoforms, we prepared stable expression lines of all ZmCKX–GFP fusions in Arabidopsis thaliana Ler suspension culture. All the ER-associated isoforms except ZmCKX1 and ZmCKX9 were found to be targeted primarily to vacuoles, suggesting that ER-localization is a transition point in the intracellular secretory pathway and vacuoles serve as these isoforms’ final destination. ZmCKX9 showed an ER-like localization pattern similar to those observed in the transient maize assay. Apoplastic localizations of ZmCKX1 was further confirmed and ZmCKX10 showed cytosolic/nuclear localization due to the absence of the signal peptide sequence as previously reported. Additionally, we prepared GFP-fused N-terminal signal deletion mutants of ZmCKX2 and ZmCKX9and clearly demonstrated that the localization pattern of these mutant forms was cytosolic/nuclear. This study provides the first complex model for spatiotemporal localization of the key enzymes of the cytokinin degradation/catabolism in monocotyledonous plants.

Item Type: Paper
Uncontrolled Keywords: Zea mays L. Cytokinin Cytokinin dehydrogenase Subcellular localization Vacuole
Subjects: organism description > plant > maize
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > phytohormones > cytokinin
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > phytohormones
organs, tissues, organelles, cell types and functions > organelles, types and functions > vacuole
CSHL Authors:
Communities: CSHL labs > Jackson lab
Depositing User: Matt Covey
Date: 14 March 2016
Date Deposited: 01 Apr 2016 19:49
Last Modified: 01 Apr 2016 19:49
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32472

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