Fig 1.
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.
Fig 2.
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.
Table 1.
Tetraploid:diploid hypocotyl cell-length ratios.
Fig 3.
Global gene expression profiles in diploid and tetraploid dark-grown hypocotyls.
(A) Scatter plot showing diploid and tetaraploid gene expression data in the apical growing region of 7-day-old dark-grown hypocotyls. Black dots represent genes whose expression levels differ by at least twofold between diploid and tetraploid. Gray dots represent genes below the twofold threshold. Genes with low signal-to-noise ratios were removed from analysis. (B) Significantly enriched Gene Ontology terms for genes whose expressions levels were at least twofold lower in tetraploid than in diploid plants. 2x, diploid plants; 4x, tetraploid plants.
Fig 4.
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).
Fig 5.
Cuticular structure in diploid and tetraploid dark-grown hypocotyls as assessed by transmission electron microscopy.
Transmission electron micrographs of cuticle in epidermal cells derived from the apical 3 mm region of 7-day-old dark-grown hypocotyl of diploid (A) and tetraploid (B) seedlings. CW, cell wall; 2x, diploid plants; 4x, tetraploid plants. Bars = 100 nm.