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Auxin regulates SNARE-dependent vacuolar morphology restricting cell size.

Löfke C, Dünser K, Scheuring D, Kleine-Vehn J - Elife (2015)

Bottom Line: Genetic and pharmacological interference with the auxin effect on vacuolar SNAREs interrelates with auxin-resistant vacuolar morphogenesis and cell size regulation.Vacuolar SNARE VTI11 is strictly required for auxin-reliant vacuolar morphogenesis and loss of function renders cells largely insensitive to auxin-dependent growth inhibition.Our data suggests that the adaptation of SNARE-dependent vacuolar morphogenesis allows auxin to limit cellular expansion, contributing to root organ growth rates.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.

ABSTRACT
The control of cellular growth is central to multicellular patterning. In plants, the encapsulating cell wall literally binds neighbouring cells to each other and limits cellular sliding/migration. In contrast to its developmental importance, growth regulation is poorly understood in plants. Here, we reveal that the phytohormone auxin impacts on the shape of the biggest plant organelle, the vacuole. TIR1/AFBs-dependent auxin signalling posttranslationally controls the protein abundance of vacuolar SNARE components. Genetic and pharmacological interference with the auxin effect on vacuolar SNAREs interrelates with auxin-resistant vacuolar morphogenesis and cell size regulation. Vacuolar SNARE VTI11 is strictly required for auxin-reliant vacuolar morphogenesis and loss of function renders cells largely insensitive to auxin-dependent growth inhibition. Our data suggests that the adaptation of SNARE-dependent vacuolar morphogenesis allows auxin to limit cellular expansion, contributing to root organ growth rates.

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PI4 kinases posttranslationally control VAMP711 abundance.(A–D) Wortmannin inhibits the auxin effect on VAMP711 stabilisation. VAMP711-YFP signal after DMSO (A) or NAA (B) (500 nM; 20 hr) (control for C and D) treatment. VAMP711-YFP seedlings treated with wortmannin (WM) (C) (10 µM; 20 hr) or WM and NAA (D) (500 nM; 20 hr). (E–H) Reduced VAMP711 abundance in pi4kß1/2 mutants. Control treatment of VAMP711-YFP with DMSO (E) or NAA (F) (500 nM; 20 hr). pi4kß1/2 seedlings expressing pUBQ10::VAMP711-YFP treated with DMSO (G) or NAA (H) (500 nM; 20 hr). VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: ***p < 0.001. Scale bar: 15 µm.DOI:http://dx.doi.org/10.7554/eLife.05868.019
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fig7s1: PI4 kinases posttranslationally control VAMP711 abundance.(A–D) Wortmannin inhibits the auxin effect on VAMP711 stabilisation. VAMP711-YFP signal after DMSO (A) or NAA (B) (500 nM; 20 hr) (control for C and D) treatment. VAMP711-YFP seedlings treated with wortmannin (WM) (C) (10 µM; 20 hr) or WM and NAA (D) (500 nM; 20 hr). (E–H) Reduced VAMP711 abundance in pi4kß1/2 mutants. Control treatment of VAMP711-YFP with DMSO (E) or NAA (F) (500 nM; 20 hr). pi4kß1/2 seedlings expressing pUBQ10::VAMP711-YFP treated with DMSO (G) or NAA (H) (500 nM; 20 hr). VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: ***p < 0.001. Scale bar: 15 µm.DOI:http://dx.doi.org/10.7554/eLife.05868.019

Mentions: (A–G) Effect of wortmannin (WM) on auxin regulated vacuolar morphology, cell growth inhibition and VAMP711 abundance. Control treatment of VAMP711-YFP atrichoblasts with DMSO (A) or NAA (B) (250 nM; 20 hr). VAMP711-YFP expressing seedlings after WM (C) (10 µM; 20 hr) or NAA/WM co-treatment (D). Quantification of vacuolar morphology (vac. morph. [µm2]) index (E) and cell length change (F). (G) Relative mean grey value of VAMP711-YFP abundance after NAA (500 nM; 20 hr) and/or WM (10 µM; 20 hr) treatment. Corresponding images are shown in Figure 7—figure supplement 1. (H–M) Effect on auxin regulated vacuolar morphology, cell growth inhibition and VAMP711 abundance in pi4kß1/2 plants. Control treatment of VAMP711-YFP atrichoblasts with DMSO (H) or NAA (I) (100 nM; 20 hr) for comparability. VAMP711-YFP expression in pi4kß1/2 mutant background after DMSO (J) or NAA (K) (100 nM; 20 hr) treatment. Quantification of vacuolar morphology (vac. morph. [µm2]) index (L) and cell length change (M). (N) Absolute mean grey value of VAMP711-YFP abundance after NAA (500 nM; 20 hr) treatment in the pi4kß1/2 mutant background. Corresponding images are shown in Figure 7—figure supplement 1. VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings for cell length measurements and n = 40 cells in eight individual seedlings for vacuolar morphology index quantification. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: **p < 0.01, ***p < 0.001. Scale bar: 15 µm.


Auxin regulates SNARE-dependent vacuolar morphology restricting cell size.

Löfke C, Dünser K, Scheuring D, Kleine-Vehn J - Elife (2015)

PI4 kinases posttranslationally control VAMP711 abundance.(A–D) Wortmannin inhibits the auxin effect on VAMP711 stabilisation. VAMP711-YFP signal after DMSO (A) or NAA (B) (500 nM; 20 hr) (control for C and D) treatment. VAMP711-YFP seedlings treated with wortmannin (WM) (C) (10 µM; 20 hr) or WM and NAA (D) (500 nM; 20 hr). (E–H) Reduced VAMP711 abundance in pi4kß1/2 mutants. Control treatment of VAMP711-YFP with DMSO (E) or NAA (F) (500 nM; 20 hr). pi4kß1/2 seedlings expressing pUBQ10::VAMP711-YFP treated with DMSO (G) or NAA (H) (500 nM; 20 hr). VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: ***p < 0.001. Scale bar: 15 µm.DOI:http://dx.doi.org/10.7554/eLife.05868.019
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fig7s1: PI4 kinases posttranslationally control VAMP711 abundance.(A–D) Wortmannin inhibits the auxin effect on VAMP711 stabilisation. VAMP711-YFP signal after DMSO (A) or NAA (B) (500 nM; 20 hr) (control for C and D) treatment. VAMP711-YFP seedlings treated with wortmannin (WM) (C) (10 µM; 20 hr) or WM and NAA (D) (500 nM; 20 hr). (E–H) Reduced VAMP711 abundance in pi4kß1/2 mutants. Control treatment of VAMP711-YFP with DMSO (E) or NAA (F) (500 nM; 20 hr). pi4kß1/2 seedlings expressing pUBQ10::VAMP711-YFP treated with DMSO (G) or NAA (H) (500 nM; 20 hr). VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: ***p < 0.001. Scale bar: 15 µm.DOI:http://dx.doi.org/10.7554/eLife.05868.019
Mentions: (A–G) Effect of wortmannin (WM) on auxin regulated vacuolar morphology, cell growth inhibition and VAMP711 abundance. Control treatment of VAMP711-YFP atrichoblasts with DMSO (A) or NAA (B) (250 nM; 20 hr). VAMP711-YFP expressing seedlings after WM (C) (10 µM; 20 hr) or NAA/WM co-treatment (D). Quantification of vacuolar morphology (vac. morph. [µm2]) index (E) and cell length change (F). (G) Relative mean grey value of VAMP711-YFP abundance after NAA (500 nM; 20 hr) and/or WM (10 µM; 20 hr) treatment. Corresponding images are shown in Figure 7—figure supplement 1. (H–M) Effect on auxin regulated vacuolar morphology, cell growth inhibition and VAMP711 abundance in pi4kß1/2 plants. Control treatment of VAMP711-YFP atrichoblasts with DMSO (H) or NAA (I) (100 nM; 20 hr) for comparability. VAMP711-YFP expression in pi4kß1/2 mutant background after DMSO (J) or NAA (K) (100 nM; 20 hr) treatment. Quantification of vacuolar morphology (vac. morph. [µm2]) index (L) and cell length change (M). (N) Absolute mean grey value of VAMP711-YFP abundance after NAA (500 nM; 20 hr) treatment in the pi4kß1/2 mutant background. Corresponding images are shown in Figure 7—figure supplement 1. VAMP711-YFP (orange) as a vacuolar marker and propidium iodide (green) for decorating the cell wall were used for confocal imaging of atrichoblast cells. n = 32 cells in eight individual seedlings for cell length measurements and n = 40 cells in eight individual seedlings for vacuolar morphology index quantification. Error bars represent s.e.m. For statistical analysis either DMSO or NAA treatments were compared between control and indicated mutant/treated seedlings. Student's t-test p-values: **p < 0.01, ***p < 0.001. Scale bar: 15 µm.

Bottom Line: Genetic and pharmacological interference with the auxin effect on vacuolar SNAREs interrelates with auxin-resistant vacuolar morphogenesis and cell size regulation.Vacuolar SNARE VTI11 is strictly required for auxin-reliant vacuolar morphogenesis and loss of function renders cells largely insensitive to auxin-dependent growth inhibition.Our data suggests that the adaptation of SNARE-dependent vacuolar morphogenesis allows auxin to limit cellular expansion, contributing to root organ growth rates.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.

ABSTRACT
The control of cellular growth is central to multicellular patterning. In plants, the encapsulating cell wall literally binds neighbouring cells to each other and limits cellular sliding/migration. In contrast to its developmental importance, growth regulation is poorly understood in plants. Here, we reveal that the phytohormone auxin impacts on the shape of the biggest plant organelle, the vacuole. TIR1/AFBs-dependent auxin signalling posttranslationally controls the protein abundance of vacuolar SNARE components. Genetic and pharmacological interference with the auxin effect on vacuolar SNAREs interrelates with auxin-resistant vacuolar morphogenesis and cell size regulation. Vacuolar SNARE VTI11 is strictly required for auxin-reliant vacuolar morphogenesis and loss of function renders cells largely insensitive to auxin-dependent growth inhibition. Our data suggests that the adaptation of SNARE-dependent vacuolar morphogenesis allows auxin to limit cellular expansion, contributing to root organ growth rates.

Show MeSH