Figure 6.

Density of the Actin Array in cpb-1 Hypocotyl Epidermal Cells Is Insensitive to Exogenous PA Treatment.

Percentage of occupancy or density was measured and binned into three regions along the axial gradient of cell expansion in 5-d-old etiolated wild-type (WT) (A) or cpb-1 (B) hypocotyls after incubation with 0, 10, 50, or 100 µM PA or with 100 µM PS for 30 min. Wild-type seedlings treated with PA have significantly increased filament density in the middle and bottom thirds of hypocotyls in a dose-dependent manner (A). By contrast, PA treatments of cpb-1 seedlings did not increase the density, but rather led to a modest decline in density at all concentrations tested (B). Treatments with another acidic phospholipid, PS, had no measurable effect on actin filament levels in either wild-type or cpb-1 seedlings. Values given are means ± se (n = 300 images from 150 cells per region; 10 hypocotyls were measured for each treatment per genotype; *P < 0.05 and **P < 0.001, analysis of variance).