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Light can rescue auxin-dependent synchrony of cell division in a tobacco cell line.

Qiao F, Petrásek J, Nick P - J. Exp. Bot. (2009)

Bottom Line: This synchrony can be inhibited by 1-N-naphthylphthalamic acid, an auxin transport inhibitor, and this process was accompanied by the disassembly of actin filaments.However, the synchrony could be rescued when the cells were cultured under white light or with exogenous indolyl-3-acetic acid.The rescue was most efficient for continuous far-red light followed by continuous blue light, whereas continuous red light was least effective.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany 1, University of Karlsruhe, Kaiserstrasse 2, Karlsruhe, Germany.

ABSTRACT
Pattern formation in plants has to cope with ambient variability and therefore must integrate environmental cues such as light. Synchrony of cell divisions was previously observed in cell files of tobacco suspension cultures, which represents a simple case of pattern formation. To develop cellular approaches for light-dependent patterning, light-responsive tobacco cell lines were screened from the cell line Nicotiana tabacum L. cv. Virginia Bright Italia 0 (VBI-0). The light responsive and auxin-autonomous cell line VBI-3 was isolated. As in the progenitor line VBI-0, cell divisions are synchronized in VBI-3 during exponential growth phase. This synchrony can be inhibited by 1-N-naphthylphthalamic acid, an auxin transport inhibitor, and this process was accompanied by the disassembly of actin filaments. However, the synchrony could be rescued when the cells were cultured under white light or with exogenous indolyl-3-acetic acid. The rescue was most efficient for continuous far-red light followed by continuous blue light, whereas continuous red light was least effective. These findings are discussed in the context of phytochrome-induced auxin biosynthesis and auxin-dependent synchrony of cell division.

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Effect of NPA on actin organization in VBI-3 cells after incubation for 2 h (B), 16 h (C), and 24 h (D). The control (A) was treated with DMSO. NPA at 5 μM was added to the medium in the presence of NAA and 2,4-D when subculturing. The cells were cultured in the dark. Projections from z-stacks through the entire cell are shown. Scale bar=20 μm.
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fig4: Effect of NPA on actin organization in VBI-3 cells after incubation for 2 h (B), 16 h (C), and 24 h (D). The control (A) was treated with DMSO. NPA at 5 μM was added to the medium in the presence of NAA and 2,4-D when subculturing. The cells were cultured in the dark. Projections from z-stacks through the entire cell are shown. Scale bar=20 μm.

Mentions: Since division synchrony has been shown to depend on actin organization (Maisch and Nick, 2007), and the effect of certain phytotropins on auxin transport has been ascribed to the induction of actin bundles (Dhonukshe et al., 2008), the response of actin filaments to NPA in VBI-3 was followed. Actin filaments were visualized by fluorescent phalloidin in combination with a mild fixation protocol after 2, 16, and 24 h of incubation with 5 μM NPA. The response of actin organization to NPA over time was followed by confocal microscopy. In the absence of NPA [but in the presence of the solvent used for NPA (DMSO) at the same concentration as in the treated samples], transvacuolar actin strands reach from the nucleus into the cell periphery and diffuse into a cortical actin array (Fig. 4A). At 2 h after addition of NPA, this cortical actin array as well as the transvacuolar strands have significantly faded, whereas the perinuclear actin array has become more prominent (Fig. 4B). This repartitioning of actin towards the nucleus leads to a situation where only a few bundles of actin emanate from the nucleus at 16 h after addition of NPA (Fig. 4C) and eventually actin disintegrates into short fragments (Fig. 4D).


Light can rescue auxin-dependent synchrony of cell division in a tobacco cell line.

Qiao F, Petrásek J, Nick P - J. Exp. Bot. (2009)

Effect of NPA on actin organization in VBI-3 cells after incubation for 2 h (B), 16 h (C), and 24 h (D). The control (A) was treated with DMSO. NPA at 5 μM was added to the medium in the presence of NAA and 2,4-D when subculturing. The cells were cultured in the dark. Projections from z-stacks through the entire cell are shown. Scale bar=20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2803214&req=5

fig4: Effect of NPA on actin organization in VBI-3 cells after incubation for 2 h (B), 16 h (C), and 24 h (D). The control (A) was treated with DMSO. NPA at 5 μM was added to the medium in the presence of NAA and 2,4-D when subculturing. The cells were cultured in the dark. Projections from z-stacks through the entire cell are shown. Scale bar=20 μm.
Mentions: Since division synchrony has been shown to depend on actin organization (Maisch and Nick, 2007), and the effect of certain phytotropins on auxin transport has been ascribed to the induction of actin bundles (Dhonukshe et al., 2008), the response of actin filaments to NPA in VBI-3 was followed. Actin filaments were visualized by fluorescent phalloidin in combination with a mild fixation protocol after 2, 16, and 24 h of incubation with 5 μM NPA. The response of actin organization to NPA over time was followed by confocal microscopy. In the absence of NPA [but in the presence of the solvent used for NPA (DMSO) at the same concentration as in the treated samples], transvacuolar actin strands reach from the nucleus into the cell periphery and diffuse into a cortical actin array (Fig. 4A). At 2 h after addition of NPA, this cortical actin array as well as the transvacuolar strands have significantly faded, whereas the perinuclear actin array has become more prominent (Fig. 4B). This repartitioning of actin towards the nucleus leads to a situation where only a few bundles of actin emanate from the nucleus at 16 h after addition of NPA (Fig. 4C) and eventually actin disintegrates into short fragments (Fig. 4D).

Bottom Line: This synchrony can be inhibited by 1-N-naphthylphthalamic acid, an auxin transport inhibitor, and this process was accompanied by the disassembly of actin filaments.However, the synchrony could be rescued when the cells were cultured under white light or with exogenous indolyl-3-acetic acid.The rescue was most efficient for continuous far-red light followed by continuous blue light, whereas continuous red light was least effective.

View Article: PubMed Central - PubMed

Affiliation: Institute of Botany 1, University of Karlsruhe, Kaiserstrasse 2, Karlsruhe, Germany.

ABSTRACT
Pattern formation in plants has to cope with ambient variability and therefore must integrate environmental cues such as light. Synchrony of cell divisions was previously observed in cell files of tobacco suspension cultures, which represents a simple case of pattern formation. To develop cellular approaches for light-dependent patterning, light-responsive tobacco cell lines were screened from the cell line Nicotiana tabacum L. cv. Virginia Bright Italia 0 (VBI-0). The light responsive and auxin-autonomous cell line VBI-3 was isolated. As in the progenitor line VBI-0, cell divisions are synchronized in VBI-3 during exponential growth phase. This synchrony can be inhibited by 1-N-naphthylphthalamic acid, an auxin transport inhibitor, and this process was accompanied by the disassembly of actin filaments. However, the synchrony could be rescued when the cells were cultured under white light or with exogenous indolyl-3-acetic acid. The rescue was most efficient for continuous far-red light followed by continuous blue light, whereas continuous red light was least effective. These findings are discussed in the context of phytochrome-induced auxin biosynthesis and auxin-dependent synchrony of cell division.

Show MeSH