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Hallberg, Henrik
Publications (6 of 6) Show all publications
Hallberg, H., Palovaara, J. & Hakman, I. (2010). Auxin polar transport and PIN localization pattern during conifer embryo development. Paper presented at FESPB 2010 Spain.
Open this publication in new window or tab >>Auxin polar transport and PIN localization pattern during conifer embryo development
2010 (English)Conference paper, Published paper (Other academic)
National Category
Botany
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:lnu:diva-6084 (URN)
Conference
FESPB 2010 Spain
Available from: 2010-06-12 Created: 2010-06-12 Last updated: 2011-06-13Bibliographically approved
Palovaara, J., Hallberg, H., Stasolla, C. & Hakman, I. (2010). Comparative expression pattern analysis of WUSCHEL-related homeobox 2 (WOX2) and WOX8⁄9 in developing seeds and somatic embryos of the gymnosperm Picea abies. New Phytologist, 188(1), 122-135
Open this publication in new window or tab >>Comparative expression pattern analysis of WUSCHEL-related homeobox 2 (WOX2) and WOX8⁄9 in developing seeds and somatic embryos of the gymnosperm Picea abies
2010 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 188, no 1, p. 122-135Article in journal (Refereed) Published
Abstract [en]

In seed plants, current knowledge concerning embryonic pattern formation by polar auxin transport (PAT) and WUSCHEL-related homeobox (WOX) gene activity is primarily derived from studies on angiosperms, while less is known about these processes in gymnosperms. In view of the differences in their embryogeny, and the fact that somatic embryogenesis is used for mass propagation of conifers, a better understanding of embryo development is vital.

The expression patterns of PaWOX2 and PaWOX8/9 were followed with quantitative reverse transcription–polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH) during seed and somatic embryo development in Norway spruce (Picea abies), and in somatic embryos treated with the PAT inhibitor N-1-naphthylphthalamic acid (NPA).

Both PaWOX2 and PaWOX8/9 were highly expressed at the early growth stages of zygotic and somatic embryos, and shared a similar expression pattern over the entire embryo. At later embryo stages, high expression of PaWOX8/9 became restricted to cotyledon primordia, epidermis, procambium and root apical meristem (RAM), which became most evident in NPA-treated somatic embryos, while expression of PaWOX2 was much lower.

Our results suggest an ancestral role of WOX in seed plant embryo development, and strengthen the proposed connection between PAT, PIN-FORMED (PIN) and WOX in the regulation of embryo patterning in seed plants.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Keywords
archegonia, conifer, in situ hybridization, N-1-naphthylphthalamic acid (NPA), PCR, polar auxin transport (PAT), rocambium, transcription factor
National Category
Botany
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:hik:diva-2929 (URN)10.1111/j.1469-8137.2010.03336.x (DOI)2-s2.0-77956295063 (Scopus ID)
Available from: 2010-03-01 Created: 2010-03-01 Last updated: 2017-12-12Bibliographically approved
Palovaara, J., Hallberg, H., Stasolla, C., Luit, B. & Hakman, I. (2010). Expression of a gymnosperm PIN homologous gene correlates with auxin immunolocalization pattern at cotyledon formation and in demarcation of the procambium during Picea abies somatic embryo development and in seedling tissues. Tree Physiology, 30(4), 479-489
Open this publication in new window or tab >>Expression of a gymnosperm PIN homologous gene correlates with auxin immunolocalization pattern at cotyledon formation and in demarcation of the procambium during Picea abies somatic embryo development and in seedling tissues
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2010 (English)In: Tree Physiology, ISSN 0829-318X, E-ISSN 1758-4469, Vol. 30, no 4, p. 479-489Article in journal (Refereed) Published
Abstract [en]

In seed plants, the body organization is established during embryogenesis and is uniform across gymnosperms and angiosperms, despite differences during early embryogeny. Evidence from angiosperms implicates the plant hormone auxin and its polar transport, mainly established by the PIN family of auxin efflux transporters, in the patterning of embryos. Here, PaPIN1 from Norway spruce (Picea abies [L.] Karst.), a gene widely expressed in conifer tissues and organs, was characterized and its expression and localization patterns were determined with reverse transcription polymerase chain reaction and in situ hybridization during somatic embryo development and in seedlings. PaPIN1 shares the predicted structure of other PIN proteins, but its central hydrophilic loop is longer than most PINs. In phylogenetic analyses, PaPIN1 clusters with Arabidopsis thaliana (L.) Heynh. PIN3, PIN4 and PIN7, but its expression pattern also suggests similarity to PIN1. The PaPIN1 expression signal was high in the protoderm of pre-cotyledonary embryos, but not if embryos were pre-treated with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). This, together with a high auxin immunolocalization signal in this cell layer, suggests a role of PaPIN1 during cotyledon formation. At later stages, high PaPIN1 expression was observed in differentiating procambium, running from the tip of incipient cotyledons down through the embryo axis and to the root apical meristem (RAM), although the mode of RAM specification in conifer embryos differs from that of most angiosperms. Also, the PaPIN1 in situ signal was high in seedling root tips including root cap columella cells. The results thus suggest that PaPIN1 provides an ancient function associated with auxin transport and embryo pattern formation prior to the separation of angiosperms and gymnosperms, in spite of some morphological differences.

Place, publisher, year, edition, pages
Oxford University Press, 2010
Keywords
conifer, embryo patterning, in situ hybridization, meristem, NPA, polar auxin transport (PAT), protoderm, RT-PCR
National Category
Botany
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:hik:diva-2928 (URN)10.1093/treephys/tpp126 (DOI)000276305100005 ()2-s2.0-77950538656 (Scopus ID)
Available from: 2010-03-01 Created: 2010-03-01 Last updated: 2017-12-12Bibliographically approved
Palovaara, J., Hallberg, H., Stasolla, C., Luit, B. & Hakman, I. (2009). Expression dynamics of PIN1 and WOX genes during Norway spruce (Picea abies) somatic embryogenesis.. In: . Paper presented at Joint Annual Meetings of the American Society of Plant Biologists and the Phycological Society of America, July 18-22, 2009 Hawaii, USA..
Open this publication in new window or tab >>Expression dynamics of PIN1 and WOX genes during Norway spruce (Picea abies) somatic embryogenesis.
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2009 (English)Conference paper, Published paper (Other academic)
National Category
Biological Sciences
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:lnu:diva-5342 (URN)
Conference
Joint Annual Meetings of the American Society of Plant Biologists and the Phycological Society of America, July 18-22, 2009 Hawaii, USA.
Available from: 2010-04-29 Created: 2010-04-29 Last updated: 2012-07-27Bibliographically approved
Hakman, I., Hallberg, H. & Palovaara, J. (2009). 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. Tree Physiology, 29(4), 483-496
Open this publication in new window or tab >>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
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
Keywords
conifer, meristem, qRT-PCR
National Category
Biological Sciences
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:hik:diva-2925 (URN)10.1093/treephys/tpn048 (DOI)
Available from: 2010-03-01 Created: 2010-03-01 Last updated: 2017-12-12Bibliographically approved
Hallberg, H. & Hakman, I. (2008). Auxin localization and polar auxin transport during somatic embryogenesis in Norway spruce.. In: . Paper presented at XVI congress of the FESPB. Tampere, Finland
Open this publication in new window or tab >>Auxin localization and polar auxin transport during somatic embryogenesis in Norway spruce.
2008 (English)Conference paper, Published paper (Other academic)
Place, publisher, year, edition, pages
Tampere, Finland: , 2008
Research subject
Natural Science, Cell and Organism Biology
Identifiers
urn:nbn:se:lnu:diva-5344 (URN)
Conference
XVI congress of the FESPB
Note
Nummer: Available from: 2010-04-29 Created: 2010-04-29 Last updated: 2012-01-03Bibliographically approved
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