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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.


Cell numbers and lengths in diploid and tetraploid hypocotyls.(A) Total cell numbers for the whole hypocotyl of 5-day-old light- and dark-grown seedlings. Error bars represent SE (n = 10). (B, C) Cell lengths in top, middle, and lower hypocotyl regions of 5-day-old light- (B) and dark-grown (C) seedlings. Error bars represent SE (n = 30 cells from ten plants). 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.g002: Cell numbers and lengths in diploid and tetraploid hypocotyls.(A) Total cell numbers for the whole hypocotyl of 5-day-old light- and dark-grown seedlings. Error bars represent SE (n = 10). (B, C) Cell lengths in top, middle, and lower hypocotyl regions of 5-day-old light- (B) and dark-grown (C) seedlings. Error bars represent SE (n = 30 cells from ten plants). 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 determine whether the promotion of hypocotyl elongation in tetraploid plants was due to an increase in cell number or to an increase in cell length, total cell numbers along the hypocotyl were counted, and average cell lengths were determined for the top, middle, and bottom hypocotyl regions. Total cell number in tetraploid plants was 90% of the cell number in diploids in both the light- and dark-grown plants (Fig 2A). Cells in tetraploid plants were significantly longer than in diploid cells, particularly in the central region (Fig 2B and 2C). The tetraploid:diploid cell-length ratio was higher in the dark-grown plants than in the light-grown plants for the whole hypocotyl region (Table 1). In light-grown plants, hypocotyl lengths did not differ significantly between diploid and tetraploid plants (Fig 1C). In these plants, the increased cell elongation in tetraploid plants was probably offset by the reduction in cell number. However, in dark-grown plants, cell elongation was predominant and overcame the diminution in cell number.


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)

Cell numbers and lengths in diploid and tetraploid hypocotyls.(A) Total cell numbers for the whole hypocotyl of 5-day-old light- and dark-grown seedlings. Error bars represent SE (n = 10). (B, C) Cell lengths in top, middle, and lower hypocotyl regions of 5-day-old light- (B) and dark-grown (C) seedlings. Error bars represent SE (n = 30 cells from ten plants). 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.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4526521&req=5

pone.0134547.g002: Cell numbers and lengths in diploid and tetraploid hypocotyls.(A) Total cell numbers for the whole hypocotyl of 5-day-old light- and dark-grown seedlings. Error bars represent SE (n = 10). (B, C) Cell lengths in top, middle, and lower hypocotyl regions of 5-day-old light- (B) and dark-grown (C) seedlings. Error bars represent SE (n = 30 cells from ten plants). 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 determine whether the promotion of hypocotyl elongation in tetraploid plants was due to an increase in cell number or to an increase in cell length, total cell numbers along the hypocotyl were counted, and average cell lengths were determined for the top, middle, and bottom hypocotyl regions. Total cell number in tetraploid plants was 90% of the cell number in diploids in both the light- and dark-grown plants (Fig 2A). Cells in tetraploid plants were significantly longer than in diploid cells, particularly in the central region (Fig 2B and 2C). The tetraploid:diploid cell-length ratio was higher in the dark-grown plants than in the light-grown plants for the whole hypocotyl region (Table 1). In light-grown plants, hypocotyl lengths did not differ significantly between diploid and tetraploid plants (Fig 1C). In these plants, the increased cell elongation in tetraploid plants was probably offset by the reduction in cell number. However, in dark-grown plants, cell elongation was predominant and overcame the diminution in cell number.

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.