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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.


Growth of diploid and tetraploid hypocotyls.(A, B) Morphology of 13-day-old light- (A) and dark-grown (B) seedlings. Bars = 2 mm. (C) Hypocotyl lengths of 13-day-old light-grown seedlings. Error bars represent SE (n = 20). (D, E) Hypocotyl lengths (D) and growth rates (E) of dark-grown seedlings. Error bars represent SE (n = 15). Where absent, error bars are smaller than the symbols. Asterisks indicate a significant difference between the diploid and tetraploid plants (**p < 0.01, *p < 0.05, Student’s t-test). 2x, diploid plants; 4x, tetraploid plants.
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pone.0134547.g001: Growth of diploid and tetraploid hypocotyls.(A, B) Morphology of 13-day-old light- (A) and dark-grown (B) seedlings. Bars = 2 mm. (C) Hypocotyl lengths of 13-day-old light-grown seedlings. Error bars represent SE (n = 20). (D, E) Hypocotyl lengths (D) and growth rates (E) of dark-grown seedlings. Error bars represent SE (n = 15). Where absent, error bars are smaller than the symbols. Asterisks indicate a significant difference between the diploid and tetraploid plants (**p < 0.01, *p < 0.05, Student’s t-test). 2x, diploid plants; 4x, tetraploid plants.

Mentions: To investigate the growth effects of increased ploidy in A. thaliana, we compared hypocotyl growth between diploid (wild-type) plants and tetraploid plants. In light-grown plants, no significant difference in overall morphological appearance was observed between diploid and tetraploid plants in either the hypocotyl or rosette leaves at various growth stages (Fig 1A and 1C), as reported previously [17]. By contrast, from day 5 onwards, hypocotyl length in dark-grown plants (Fig 1B and 1D) was significantly longer in tetraploid plants than in diploid plants. In addition, for days 5–11, the increment of hypocotyl length per day in dark-grown plants was higher in tetraploid than in diploid plants. This suggests that the promotion of hypocotyl elongation in tetraploid plants occurred as a result of a higher elongation rate in these plants compared to diploid plants (Fig 1E).


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)

Growth of diploid and tetraploid hypocotyls.(A, B) Morphology of 13-day-old light- (A) and dark-grown (B) seedlings. Bars = 2 mm. (C) Hypocotyl lengths of 13-day-old light-grown seedlings. Error bars represent SE (n = 20). (D, E) Hypocotyl lengths (D) and growth rates (E) of dark-grown seedlings. Error bars represent SE (n = 15). Where absent, error bars are smaller than the symbols. Asterisks indicate a significant difference between the diploid and tetraploid plants (**p < 0.01, *p < 0.05, Student’s t-test). 2x, diploid plants; 4x, tetraploid plants.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526521&req=5

pone.0134547.g001: Growth of diploid and tetraploid hypocotyls.(A, B) Morphology of 13-day-old light- (A) and dark-grown (B) seedlings. Bars = 2 mm. (C) Hypocotyl lengths of 13-day-old light-grown seedlings. Error bars represent SE (n = 20). (D, E) Hypocotyl lengths (D) and growth rates (E) of dark-grown seedlings. Error bars represent SE (n = 15). Where absent, error bars are smaller than the symbols. Asterisks indicate a significant difference between the diploid and tetraploid plants (**p < 0.01, *p < 0.05, Student’s t-test). 2x, diploid plants; 4x, tetraploid plants.
Mentions: To investigate the growth effects of increased ploidy in A. thaliana, we compared hypocotyl growth between diploid (wild-type) plants and tetraploid plants. In light-grown plants, no significant difference in overall morphological appearance was observed between diploid and tetraploid plants in either the hypocotyl or rosette leaves at various growth stages (Fig 1A and 1C), as reported previously [17]. By contrast, from day 5 onwards, hypocotyl length in dark-grown plants (Fig 1B and 1D) was significantly longer in tetraploid plants than in diploid plants. In addition, for days 5–11, the increment of hypocotyl length per day in dark-grown plants was higher in tetraploid than in diploid plants. This suggests that the promotion of hypocotyl elongation in tetraploid plants occurred as a result of a higher elongation rate in these plants compared to diploid plants (Fig 1E).

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.