lnu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The polar auxin transport inhibitor NPA impairs embryo morphology and increases the expression of an auxin efflux facilitator protein PIN during Picea abies somatic embryo development
University of Kalmar, School of Pure and Applied Natural Sciences. (Inger Hakman)
University of Kalmar, School of Pure and Applied Natural Sciences. (Inger Hakman)
University of Kalmar, School of Pure and Applied Natural Sciences. (Inger Hakman)
2009 (English)In: Tree Physiology, ISSN 0829-318X, E-ISSN 1758-4469, Vol. 29, no 4, p. 483-496Article in journal (Refereed) Published
Abstract [en]

Auxin and polar auxin transport have been implicated in controlling embryo patterning and development in angiosperms but less is known from the gymnosperms. The aims of this study were to determine at what stages of conifer embryo development auxin and polar auxin transport are the most important for normal development and to analyze the changes in embryos after treatment with the polar auxin inhibitor N-1-naphthylphthalamic acid (NPA). For these studies, somatic embryos of Norway spruce (Picea abies L. Karst) were used. Growth on medium containing NPA leads to the formation of embryos with poor shoot apical meristem (SAM) and fused cotyledons, and to a pin-formed phenotype of the regenerated plantlets. The effect of NPA on embryo morphology was most severe if embryos were transferred to NPA-containing medium immediately before cotyledon initiation and SAM specification. Indole-3-acetic acid (IAA) was identified by immunolocalization in developing embryos. The highest staining intensity was seen in early staged embryos and then decreased as the embryos matured. No clear IAA-maxima was seen, although the apical parts of embryos, particularly the protoderm, and the suspensor cells appear to accumulate more IAA, as reflected by the staining pattern. The NPA treatment also caused expanded procambium and a broader root apical meristem in embryos, and a significant increase in the expression of a PIN1-like gene. Taken together, our results show that, for proper cotyledon initiation, correct auxin transport is needed only during a short period at the transition stage of embryo development, probably involving PIN efflux proteins and that a common mechanism is behind proper cotyledon formation within the species of angiosperms and conifers, despite their cotyledon number which normally differs.

Place, publisher, year, edition, pages
Oxford University Press , 2009. Vol. 29, no 4, p. 483-496
Keywords [en]
conifer, meristem, qRT-PCR
National Category
Biological Sciences
Research subject
Natural Science, Cell and Organism Biology
Identifiers
URN: urn:nbn:se:hik:diva-2925DOI: 10.1093/treephys/tpn048OAI: oai:DiVA.org:hik-2925DiVA, id: diva2:300806
Available from: 2010-03-01 Created: 2010-03-01 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Conifer embryology: a study of polar auxin transport and WOX transcription factors
Open this publication in new window or tab >>Conifer embryology: a study of polar auxin transport and WOX transcription factors
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Plants, like animals, use endogenous signaling molecules to coordinate their own physiology and development. One such molecule in plants is the hormone auxin and recent research has implicated auxin and its polar transport, together with the WOX transcription factors, in regulating embryo patterning and development in angiosperms (flowering plants), the most diverse group of land plants. No extensive investigation of this has been carried out on the more evolutionary distant gymnosperms, the other major taxa of seed plants. Thus, in this thesis I, together with my co-authors, have analyzed the regulation of embryonic pattern formation in the coniferous gymnosperm Picea abies (Norway spruce) using seed and somatic embryos. Conifers are important forestry species and knowledge of their embryology is vital for reforestration programs, where the method of somatic embryogenesis is employed for mass propagation as well as it is used as a model system for embryo development.

Mature spruce embryos display a basic body plan and contain a shoot apical meristem (SAM), cotyledons, hypocotyl, embryonic root and a root apical meristem (RAM), with the meristems generating differentiated cells for organ formation. Treatment of embryos with a polar auxin transport (PAT) inhibitor produce embryos with poor SAM and, in some cases, fused cotyledons. Thus, PAT is essential for the correct patterning of conifer embryos. In angiosperms, PAT is mainly established and maintained by members of the auxin efflux facilitator PIN-FORMED (PIN) family. I isolated a PIN homologue (PaPIN1), of high abundance in conifer tissues, that is localized, together with auxin, to the epidermis of precotyledonary spruce embryos and upregulated as well as delocalized from the epidermis in early PAT inhibited embryos. Since also auxin concentration seems to decrease in the epidermis of these embryos, my data indicate that local auxin accumulation in the epidermis is mediated by PIN-dependent auxin transport.

Further, I investigated WOX genes in conifers and isolated two homologues, PaWOX2 and PaWOX8/9, that are expressed throughout spruce embryo development. Their expression profile suggests involvement in cell proliferation and specification, and, indeed, they both serve as markers for conifer somatic embryogenesis. The expression of PaWOX2 and PaWOX8/9 overlap with PaPIN1 in differentiating vascular tissue (procambium) of spruce embryos and is also upregulated in early PAT inhibited embryos. Thus, PaWOX2, PaWOX8/9, and PaPIN1 may all act together in procambium differentiation. With this, I conclude that a common mechanism, involving PAT and WOX, regulate embryo pattern formation in seed plants. Results in post-embryonic tissue imply a common mechanism regulating pattern formation also here.

Place, publisher, year, edition, pages
Kalmar/Växjö: Linnaeus University Press, 2010
Series
Linnaeus University Dissertations ; 10/2010
National Category
Botany
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:hik:diva-2932 (URN)978-91-86491-12-3 (ISBN)
Public defence
2010-04-16, Hörsalen Fullrigaren, Landgången 4, Kalmar, 09:30 (English)
Opponent
Supervisors
Available from: 2010-04-09 Created: 2010-03-01 Last updated: 2014-05-12Bibliographically approved

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full texthttp://treephys.oxfordjournals.org/cgi/reprint/29/4/483

Authority records BETA

Hakman, IngerHallberg, HenrikPalovaara, Joakim

Search in DiVA

By author/editor
Hakman, IngerHallberg, HenrikPalovaara, Joakim
By organisation
School of Pure and Applied Natural Sciences
In the same journal
Tree Physiology
Biological Sciences

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 192 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf