University of Oulu

Vuosku J, Muilu-Mäkelä R, Avia K, Suokas M, Kestilä J, Läärä E, Häggman H, Savolainen O and Sarjala T (2019) Thermospermine Synthase (ACL5) and Diamine Oxidase (DAO) Expression Is Needed for Zygotic Embryogenesis and Vascular Development in Scots Pine. Front. Plant Sci. 10:1600. doi: 10.3389/fpls.2019.01600

Thermospermine synthase (ACL5) and diamine oxidase (DAO) expression is needed for zygotic embryogenesis and vascular development in Scots pine

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Author: Vuosku, Jaana1; Muilu-Mäkelä, Riina2; Avia, Komlan1;
Organizations: 1Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
2Production Systems, Natural Resources Institute Finland, Espoo, Finland
3Research Unit of Mathematical Sciences, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.3 MB)
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Language: English
Published: Frontiers Media, 2019
Publish Date: 2020-02-12


Unlike in flowering plants, the detailed roles of the enzymes in the polyamine (PA) pathway in conifers are poorly known. We explored the sequence conservation of the PA biosynthetic genes and diamine oxidase (DAO) in conifers and flowering plants to reveal the potential functional diversification of the enzymes between the plant lineages. The expression of the genes showing different selective constraints was studied in Scots pine zygotic embryogenesis and early seedling development. We found that the arginine decarboxylase pathway is strongly preferred in putrescine production in the Scots pine as well as generally in conifers and that the reduced use of ornithine decarboxylase (ODC) has led to relaxed purifying selection in ODC genes. Thermospermine synthase (ACL5) genes evolve under strong purifying selection in conifers and the DAO gene is also highly conserved in pines. In developing Scots pine seeds, the expression of both ACL5 and DAO increased as embryogenesis proceeded. Strong ACL5 expression was present in the procambial cells of the embryo and in the megagametophyte cells destined to die via morphologically necrotic cell death. Thus, the high sequence conservation of ACL5 genes in conifers may indicate the necessity of ACL5 for both embryogenesis and vascular development. Moreover, the result suggests the involvement of ACL5 in morphologically necrotic cell death and supports the view of the genetic regulation of necrosis in Scots pine embryogenesis and in plant development. DAO transcripts were located close to the cell walls and between the walls of adjacent cells in Scots pine zygotic embryos and in the roots of young seedlings. We propose that DAO, in addition to the role in Put oxidation for providing H₂O₂ during the cell-wall structural processes, may also participate in cell-to-cell communication at the mRNA level. To conclude, our findings indicate that the PA pathway of Scots pines possesses several special functional characteristics which differ from those of flowering plants.

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Series: Frontiers in plant science
ISSN: 1664-462X
ISSN-E: 1664-462X
ISSN-L: 1664-462X
Volume: 10
Article number: 1600
DOI: 10.3389/fpls.2019.01600
Type of Publication: A1 Journal article – refereed
Field of Science: 1183 Plant biology, microbiology, virology
Funding: The Research was funded by the Academy of Finland (Project 121994 to TS) and by grants from the Finnish Cultural Foundation and the Niemi Foundation (to JV). OS and KA acknowledge EU project Noveltree (FP7211868) and Biocenter Oulu.
EU Grant Number: (211868) NOVELTREE - Novel tree breeding strategies
Copyright information: © 2019 Vuosku, Muilu-Mäkelä, Avia, Suokas, Kestilä, Läärä, Häggman, Savolainen and Sarjala. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.