Figure 2.

HDA15 is a negative regulator of hypocotyl cell elongation in photomorphogenesis. A, Phenotypes of 4-d–old Col-0, hda15-1, 35S:HDA15-GFP, phyB-9, and 35S:HDA15-GFP phyB seedlings grown under red light (13.12 μmol m⁻² s⁻¹). 35S:HDA15-GFP-1 and 35S:HDA15-GFP-2 are two independent HDA15 transgenic lines. Bar = 2 mm. B, Quantification of the hypocotyl length as indicated in (A). Asterisks indicate the significant difference (P < 0.05, Student’s t test; n > 20). C, Phenotypes of 4-d–old Col-0, hda15-1, 35S:HDA15-GFP, phyA-211, and 35S:HDA15-GFP phyA seedlings grown under far-red light (3.82 μmol m⁻² s⁻¹). Bar = 2 mm. D, Quantification of the hypocotyl length as indicated in (C). Asterisks indicate the significant difference (P < 0.05, Student’s t test; n > 20). E, Scanning electron microscopy analysis of hypocotyl cells of 4-d–old Col-0 and hda15-1 seedlings grown under red light (13.12 μmol m⁻² s⁻¹). Bar = 100 μm. F, Quantification of the cell length as indicated in (E). Asterisk indicates the significant difference (P < 0.05, Student’s t test; n > 30). G, Quantification of the cell number as indicated in (E; n > 30).