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New Phytol. 2020 Mar;225(5):2064-2076. doi: 10.1111/nph.16291. Epub 2019 Dec 2.

Ribosome assembly factor Adenylate Kinase 6 maintains cell proliferation and cell size homeostasis during root growth.

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Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr Bohr-Gasse 3, 1030, Vienna, Austria.
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.
Max F. Perutz Laboratories (MFPL), Vienna Biocenter (VBC), Dr Bohr-Gasse 9, 1030, Vienna, Austria.
Laboratory for Integrated Molecular Plant Physiology Research (IMPRES), Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerpen, Belgium.
Plant Molecular and Cellular Biology Laboratory, Salk Institute For Biological Studies, 10010 N Torrey Pines Rd, La Jolla, CA, 92037, USA.


From the cellular perspective, organ growth is determined by production and growth of cells. Uncovering how these two processes are coordinated is essential for understanding organogenesis and regulation of organ growth. We utilized phenotypic and genetic variation of 252 natural accessions of Arabidopsis thaliana to conduct genome-wide association studies (GWAS) for identifying genes underlying root growth variation; using a T-DNA line candidate approach, we identified one gene involved in root growth control and characterized its function using microscopy, root growth kinematics, G2/M phase cell count, ploidy levels and ribosome polysome profiles. We identified a factor contributing to root growth control: Arabidopsis Adenylate Kinase 6 (AAK6). AAK6 is required for normal cell production and normal cell elongation, and its natural genetic variation is involved in determining root growth differences between Arabidopsis accessions. A lack of AAK6 reduces cell production in the aak6 root apex, but this is partially compensated for by longer mature root cells. Thereby, aak6 mutants exhibit compensatory cell enlargement, a phenomenon unexpected in roots. Moreover, aak6 plants accumulate 80S ribosomes while the polysome profile remains unchanged, consistent with a phenotype of perturbed ribosome biogenesis. In conclusion, AAK6 impacts ribosome abundance, cell production and thereby root growth.


Arabidopsis thaliana ; cell elongation; cell proliferation; natural variation; ribosome biogenesis; root growth and development


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