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Stimulation of Cell Elongation by Tetraploidy in Hypocotyls of Dark-Grown Arabidopsis Seedlings.

Narukawa H, Yokoyama R, Komaki S, Sugimoto K, Nishitani K - PLoS ONE (2015)

Bottom Line: The longer hypocotyl in the tetraploid seedlings developed as a result of enhanced cell elongation rather than by an increase in cell number.DNA microarray analysis showed that genes involved in the transport of cuticle precursors were downregulated in a defined region of the tetraploid hypocotyl when compared to the diploid hypocotyl.Taken together, these data indicate that promotion of cell elongation is responsible for ploidy-dependent size determination in the Arabidopsis hypocotyl, and that this process is directly or indirectly related to cuticular function.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Plant Cell Wall Biology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.

ABSTRACT
Plant size is largely determined by the size of individual cells. A number of studies showed a link between ploidy and cell size in land plants, but this link remains controversial. In this study, post-germination growth, which occurs entirely by cell elongation, was examined in diploid and autotetraploid hypocotyls of Arabidopsis thaliana (L.) Heynh. Final hypocotyl length was longer in tetraploid plants than in diploid plants, particularly when seedlings were grown in the dark. The longer hypocotyl in the tetraploid seedlings developed as a result of enhanced cell elongation rather than by an increase in cell number. DNA microarray analysis showed that genes involved in the transport of cuticle precursors were downregulated in a defined region of the tetraploid hypocotyl when compared to the diploid hypocotyl. Cuticle permeability, as assessed by toluidine-blue staining, and cuticular structure, as visualized by electron microscopy, were altered in tetraploid plants. Taken together, these data indicate that promotion of cell elongation is responsible for ploidy-dependent size determination in the Arabidopsis hypocotyl, and that this process is directly or indirectly related to cuticular function.

No MeSH data available.


Cuticular barrier function in diploid and tetraploid hypocotyls as visualized by toluidine-blue staining.(A, B) 5-day-old (A) and 7-day-old (B) dark-grown seedlings stained with toluidine blue (TB). (C) 7-day-old light-grown seedlings stained with TB. (D) Unstained 7-day-old light-grown seedlings shown as control for Fig 4C. 2x, diploid plants; 4x, tetraploid plants. Bars = 2 mm (A, B), 500 μm (C, D).
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pone.0134547.g004: Cuticular barrier function in diploid and tetraploid hypocotyls as visualized by toluidine-blue staining.(A, B) 5-day-old (A) and 7-day-old (B) dark-grown seedlings stained with toluidine blue (TB). (C) 7-day-old light-grown seedlings stained with TB. (D) Unstained 7-day-old light-grown seedlings shown as control for Fig 4C. 2x, diploid plants; 4x, tetraploid plants. Bars = 2 mm (A, B), 500 μm (C, D).

Mentions: The results of GO analysis implied that the structural and/or functional features of epidermal cuticle might be altered in tetraploid hypocotyls. Accordingly, we examined the chemical properties of the cuticle using toluidine-blue (TB). Penetrance of TB is indicative of defects in the barrier function of the cuticle against water and hydrophilic compounds [16]. Patterns of TB staining varied between diploid and tetraploid hypocotyls depending on the growth stage. In 5-day-old dark-grown seedlings, TB staining was not noticeable in the diploid hypocotyl but was apparent in the apical region of tetraploid hypocotyls (Fig 4A). In 7-day-old dark-grown seedlings, TB staining was restricted to the apical region in the diploid hypocotyls, whereas staining extended to subapical non-growing regions of the hypocotyl in tetraploid plants (Fig 4B). No TB staining was observed in light-grown hypocotyls, irrespective of ploidy level (Fig 4C and 4D). TB-stained regions on dark-grown hypocotyls largely correlated with the actively growing regions. It is possible that the altered cuticle barrier in dark-grown seedlings may reflect changes to structural features that are associated with an enhanced growth rate.


Stimulation of Cell Elongation by Tetraploidy in Hypocotyls of Dark-Grown Arabidopsis Seedlings.

Narukawa H, Yokoyama R, Komaki S, Sugimoto K, Nishitani K - PLoS ONE (2015)

Cuticular barrier function in diploid and tetraploid hypocotyls as visualized by toluidine-blue staining.(A, B) 5-day-old (A) and 7-day-old (B) dark-grown seedlings stained with toluidine blue (TB). (C) 7-day-old light-grown seedlings stained with TB. (D) Unstained 7-day-old light-grown seedlings shown as control for Fig 4C. 2x, diploid plants; 4x, tetraploid plants. Bars = 2 mm (A, B), 500 μm (C, D).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526521&req=5

pone.0134547.g004: Cuticular barrier function in diploid and tetraploid hypocotyls as visualized by toluidine-blue staining.(A, B) 5-day-old (A) and 7-day-old (B) dark-grown seedlings stained with toluidine blue (TB). (C) 7-day-old light-grown seedlings stained with TB. (D) Unstained 7-day-old light-grown seedlings shown as control for Fig 4C. 2x, diploid plants; 4x, tetraploid plants. Bars = 2 mm (A, B), 500 μm (C, D).
Mentions: The results of GO analysis implied that the structural and/or functional features of epidermal cuticle might be altered in tetraploid hypocotyls. Accordingly, we examined the chemical properties of the cuticle using toluidine-blue (TB). Penetrance of TB is indicative of defects in the barrier function of the cuticle against water and hydrophilic compounds [16]. Patterns of TB staining varied between diploid and tetraploid hypocotyls depending on the growth stage. In 5-day-old dark-grown seedlings, TB staining was not noticeable in the diploid hypocotyl but was apparent in the apical region of tetraploid hypocotyls (Fig 4A). In 7-day-old dark-grown seedlings, TB staining was restricted to the apical region in the diploid hypocotyls, whereas staining extended to subapical non-growing regions of the hypocotyl in tetraploid plants (Fig 4B). No TB staining was observed in light-grown hypocotyls, irrespective of ploidy level (Fig 4C and 4D). TB-stained regions on dark-grown hypocotyls largely correlated with the actively growing regions. It is possible that the altered cuticle barrier in dark-grown seedlings may reflect changes to structural features that are associated with an enhanced growth rate.

Bottom Line: The longer hypocotyl in the tetraploid seedlings developed as a result of enhanced cell elongation rather than by an increase in cell number.DNA microarray analysis showed that genes involved in the transport of cuticle precursors were downregulated in a defined region of the tetraploid hypocotyl when compared to the diploid hypocotyl.Taken together, these data indicate that promotion of cell elongation is responsible for ploidy-dependent size determination in the Arabidopsis hypocotyl, and that this process is directly or indirectly related to cuticular function.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Plant Cell Wall Biology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.

ABSTRACT
Plant size is largely determined by the size of individual cells. A number of studies showed a link between ploidy and cell size in land plants, but this link remains controversial. In this study, post-germination growth, which occurs entirely by cell elongation, was examined in diploid and autotetraploid hypocotyls of Arabidopsis thaliana (L.) Heynh. Final hypocotyl length was longer in tetraploid plants than in diploid plants, particularly when seedlings were grown in the dark. The longer hypocotyl in the tetraploid seedlings developed as a result of enhanced cell elongation rather than by an increase in cell number. DNA microarray analysis showed that genes involved in the transport of cuticle precursors were downregulated in a defined region of the tetraploid hypocotyl when compared to the diploid hypocotyl. Cuticle permeability, as assessed by toluidine-blue staining, and cuticular structure, as visualized by electron microscopy, were altered in tetraploid plants. Taken together, these data indicate that promotion of cell elongation is responsible for ploidy-dependent size determination in the Arabidopsis hypocotyl, and that this process is directly or indirectly related to cuticular function.

No MeSH data available.