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Science. 2014 Aug 22;345(6199):933-7. doi: 10.1126/science.1253736. Epub 2014 Jul 31.

Plant development. Arabidopsis NAC45/86 direct sieve element morphogenesis culminating in enucleation.

Author information

1
Institute of Biotechnology, Department of Biological and Environmental Sciences, University of Helsinki, FIN-00014, Finland.
2
Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, B-9052 Gent, Belgium. Department of Plant System Biology, VIB, Technologiepark 927, B-9052 Gent, Belgium.
3
Institute of Biotechnology, Department of Biological and Environmental Sciences, University of Helsinki, FIN-00014, Finland. yrjo.helariutta@slcu.cam.ac.uk eija.jokitalo@helsinki.fi.
4
Institute of Biotechnology, Department of Biological and Environmental Sciences, University of Helsinki, FIN-00014, Finland. Cardiff University Cardiff School of Biosciences, The Sir Martin Evans Building, Museum Avenue, Cardiff, CF10 3AX, UK. The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK. yrjo.helariutta@slcu.cam.ac.uk eija.jokitalo@helsinki.fi.

Abstract

Photoassimilates such as sugars are transported through phloem sieve element cells in plants. Adapted for effective transport, sieve elements develop as enucleated living cells. We used electron microscope imaging and three-dimensional reconstruction to follow sieve element morphogenesis in Arabidopsis. We show that sieve element differentiation involves enucleation, in which the nuclear contents are released and degraded in the cytoplasm at the same time as other organelles are rearranged and the cytosol is degraded. These cellular reorganizations are orchestrated by the genetically redundant NAC domain-containing transcription factors, NAC45 and NAC86 (NAC45/86). Among the NAC45/86 targets, we identified a family of genes required for enucleation that encode proteins with nuclease domains. Thus, sieve elements differentiate through a specialized autolysis mechanism.

PMID:
25081480
DOI:
10.1126/science.1253736
[Indexed for MEDLINE]
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