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Distribution of lipid transfer protein 1 (LTP1) epitopes associated with morphogenic events during somatic embryogenesis of Arabidopsis thaliana.

Potocka I, Baldwin TC, Kurczynska EU - Plant Cell Rep. (2012)

Bottom Line: The labelling was strongest in both the outer periclinal and anticlinal walls of the adaxial, protodermal cells of the proximal region of the cotyledon.The putative role(s) of lipid transfer proteins in the formation of lipid lamellae and in cell differentiation are discussed.Key message Occurrence of lipid transfer protein 1 epitopes in Arabidopsis explant cells accompanies changes in cell fate and may be correlated with the deposition of lipid substances in the cell walls.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Biology, University of Silesia, Jagiellońska 28, 40-032, Katowice, Poland. izabela.potocka@us.edu.pl

ABSTRACT
Using immunocytochemical methods, at both the light and electron microscopic level, we have investigated the spatial and temporal distribution of lipid transfer protein 1 (LTP1) epitopes during the induction of somatic embryogenesis in explants of Arabidopsis thaliana. Immunofluorescence labelling demonstrated the presence of high levels of LTP1 epitopes within the proximal regions of the cotyledons (embryogenic regions) associated with particular morphogenetic events, including intense cell division activity, cotyledon swelling, cell loosening and callus formation. Precise analysis of the signal localization in protodermal and subprotodermal cells indicated that cells exhibiting features typical of embryogenic cells were strongly labelled, both in walls and the cytoplasm, while in the majority of meristematic-like cells no signal was observed. Staining with lipophilic dyes revealed a correlation between the distribution of LTP1 epitopes and lipid substances within the cell wall. Differences in label abundance and distribution between embryogenic and non-embryogenic regions of explants were studied in detail with the use of immunogold electron microscopy. The labelling was strongest in both the outer periclinal and anticlinal walls of the adaxial, protodermal cells of the proximal region of the cotyledon. The putative role(s) of lipid transfer proteins in the formation of lipid lamellae and in cell differentiation are discussed. Key message Occurrence of lipid transfer protein 1 epitopes in Arabidopsis explant cells accompanies changes in cell fate and may be correlated with the deposition of lipid substances in the cell walls.

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Immunofluorescence localization of LTP1 epitopes in callus and embryogenic cell complexes. a A section of the cotyledon of an explant cultured for 15 days, label restricted to the callus-coated periphery of the cotyledon. b Negative control for a, no labelling visible. c, e Detailed views of the cotyledon periphery, LTP1 epitopes present in the thickened cell walls enclosing embryogenic-like complexes (arrowheads), the recently formed walls are less intensely labelled, strong signal in the walls and cytoplasm of callus cells (c, arrow). d, f, g Consecutive sections of samples shown in c, e, stained with Toluidine Blue O (d, f) and DAPI (g), showing cytological characteristics of cells within complexes. Scale bars 50 μm (a, b), 20 μm (c–g)
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Fig3: Immunofluorescence localization of LTP1 epitopes in callus and embryogenic cell complexes. a A section of the cotyledon of an explant cultured for 15 days, label restricted to the callus-coated periphery of the cotyledon. b Negative control for a, no labelling visible. c, e Detailed views of the cotyledon periphery, LTP1 epitopes present in the thickened cell walls enclosing embryogenic-like complexes (arrowheads), the recently formed walls are less intensely labelled, strong signal in the walls and cytoplasm of callus cells (c, arrow). d, f, g Consecutive sections of samples shown in c, e, stained with Toluidine Blue O (d, f) and DAPI (g), showing cytological characteristics of cells within complexes. Scale bars 50 μm (a, b), 20 μm (c–g)

Mentions: Significant labelling was associated with callus formed by explants cultured for 10–15 days (Fig. 3a). In the callus cells, the signal was localized both in the walls and cytoplasm (Fig. 3a, c). LTP1 epitopes were also secreted outside the cells into the medium (Fig. 3c). On the surface of the callused cotyledons, there were characteristic groups of cells of common origin (Fig. 3c–g) clearly distinguishable by their thickened external walls. The walls of all cells in these embryogenic complexes exhibited a punctate labelling pattern. Moreover, the intensity of this labelling correlated with the thickness of the walls and it was strongest in walls delimiting the complexes (Fig. 3c, e). In the micrographs of sections stained with either Toluidine Blue O (Fig. 3d, f) or DAPI (Fig. 3g) cut in series with those presented in Fig. 3c, e, a large nucleus with a prominent nucleolus, small vacuoles and numerous amyloplasts are all clearly visible.Fig. 3


Distribution of lipid transfer protein 1 (LTP1) epitopes associated with morphogenic events during somatic embryogenesis of Arabidopsis thaliana.

Potocka I, Baldwin TC, Kurczynska EU - Plant Cell Rep. (2012)

Immunofluorescence localization of LTP1 epitopes in callus and embryogenic cell complexes. a A section of the cotyledon of an explant cultured for 15 days, label restricted to the callus-coated periphery of the cotyledon. b Negative control for a, no labelling visible. c, e Detailed views of the cotyledon periphery, LTP1 epitopes present in the thickened cell walls enclosing embryogenic-like complexes (arrowheads), the recently formed walls are less intensely labelled, strong signal in the walls and cytoplasm of callus cells (c, arrow). d, f, g Consecutive sections of samples shown in c, e, stained with Toluidine Blue O (d, f) and DAPI (g), showing cytological characteristics of cells within complexes. Scale bars 50 μm (a, b), 20 μm (c–g)
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Related In: Results  -  Collection

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Fig3: Immunofluorescence localization of LTP1 epitopes in callus and embryogenic cell complexes. a A section of the cotyledon of an explant cultured for 15 days, label restricted to the callus-coated periphery of the cotyledon. b Negative control for a, no labelling visible. c, e Detailed views of the cotyledon periphery, LTP1 epitopes present in the thickened cell walls enclosing embryogenic-like complexes (arrowheads), the recently formed walls are less intensely labelled, strong signal in the walls and cytoplasm of callus cells (c, arrow). d, f, g Consecutive sections of samples shown in c, e, stained with Toluidine Blue O (d, f) and DAPI (g), showing cytological characteristics of cells within complexes. Scale bars 50 μm (a, b), 20 μm (c–g)
Mentions: Significant labelling was associated with callus formed by explants cultured for 10–15 days (Fig. 3a). In the callus cells, the signal was localized both in the walls and cytoplasm (Fig. 3a, c). LTP1 epitopes were also secreted outside the cells into the medium (Fig. 3c). On the surface of the callused cotyledons, there were characteristic groups of cells of common origin (Fig. 3c–g) clearly distinguishable by their thickened external walls. The walls of all cells in these embryogenic complexes exhibited a punctate labelling pattern. Moreover, the intensity of this labelling correlated with the thickness of the walls and it was strongest in walls delimiting the complexes (Fig. 3c, e). In the micrographs of sections stained with either Toluidine Blue O (Fig. 3d, f) or DAPI (Fig. 3g) cut in series with those presented in Fig. 3c, e, a large nucleus with a prominent nucleolus, small vacuoles and numerous amyloplasts are all clearly visible.Fig. 3

Bottom Line: The labelling was strongest in both the outer periclinal and anticlinal walls of the adaxial, protodermal cells of the proximal region of the cotyledon.The putative role(s) of lipid transfer proteins in the formation of lipid lamellae and in cell differentiation are discussed.Key message Occurrence of lipid transfer protein 1 epitopes in Arabidopsis explant cells accompanies changes in cell fate and may be correlated with the deposition of lipid substances in the cell walls.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cell Biology, University of Silesia, Jagiellońska 28, 40-032, Katowice, Poland. izabela.potocka@us.edu.pl

ABSTRACT
Using immunocytochemical methods, at both the light and electron microscopic level, we have investigated the spatial and temporal distribution of lipid transfer protein 1 (LTP1) epitopes during the induction of somatic embryogenesis in explants of Arabidopsis thaliana. Immunofluorescence labelling demonstrated the presence of high levels of LTP1 epitopes within the proximal regions of the cotyledons (embryogenic regions) associated with particular morphogenetic events, including intense cell division activity, cotyledon swelling, cell loosening and callus formation. Precise analysis of the signal localization in protodermal and subprotodermal cells indicated that cells exhibiting features typical of embryogenic cells were strongly labelled, both in walls and the cytoplasm, while in the majority of meristematic-like cells no signal was observed. Staining with lipophilic dyes revealed a correlation between the distribution of LTP1 epitopes and lipid substances within the cell wall. Differences in label abundance and distribution between embryogenic and non-embryogenic regions of explants were studied in detail with the use of immunogold electron microscopy. The labelling was strongest in both the outer periclinal and anticlinal walls of the adaxial, protodermal cells of the proximal region of the cotyledon. The putative role(s) of lipid transfer proteins in the formation of lipid lamellae and in cell differentiation are discussed. Key message Occurrence of lipid transfer protein 1 epitopes in Arabidopsis explant cells accompanies changes in cell fate and may be correlated with the deposition of lipid substances in the cell walls.

Show MeSH
Related in: MedlinePlus