Analysis of actin organization in leaf pavement cells of
arp2-1 and arp3-1 plants. A, F-actin
organization in leaf pavement cells from arp2-1 and
arp3-1 plants visualized by GFP-mTalin at different
developmental stages. Leaves from 10-d-old plants were bombarded with
GFP-mTalin construct, and cells expressing GFP-mTalin were imaged using
confocal microscopy as described in the text. Pavement cells at three
developmental stages are shown: b, g, and k, Stage I cells before lobe
initiation; c, h, and m, stage II cells forming lobes; and e, j, and o, stage
III cells with fully extended lobes. More than 60 cells were imaged for each
stage of cell in every genotype. Shown are cells with representative actin
organization. a to e, Leaf pavement cells of WT plants. f to j, Leaf epidermal
cells of arp3-1 plants. k to o, Leaf epidermal cells of
arp2-1 plants. a, c, e, f, h, j, k, m, and o show
three-dimensional images projected from laser scanning. b, d, g, i, l, and n
are single medial sections of a, c, f, h, k, and m, respectively. Arrows in c,
h, and m point to the diffuse F-actin patches associated with growing lobes.
Arrowheads in h and m point to diffuse F-actin associated with neck regions.
Asterisks in h and i indicate the nucleus of the cell. Bar = 15 μm for all
images. B, Quantitative analysis of association of diffuse cortical F-actin
with the tip of expanding lobes in pavement cells. Measurements were done on
30 stage II cells by visual examination. The percentage of strong diffuse
cortical F-actin associated with lobes for WT, arp2-1, and
arp3-1 pavement cells are 70.83 ± 10.57, 50.22
± 12.08, and 47.08 ± 10.91, respectively. Statistical analyses
(t test) showed that the percentage of strong diffuse F-actin
associated with lobes of both mutant pavement cells is significantly reduced
(n = 30, P ≤ 0.05).