Figure 6.

IRX9-GFP and xylan are spatially segregated in different regions of golgi cisternae. A, Anti-GFP labeling of Golgi in SCW-producing cells in a plant containing IRX9-GFP. Black circles outline gold particles. Scale bar = 200 nm. B, Anti-GFP signal above background label. Distribution of gold label among Golgi in SCW-producing negative controls that lack IRX9-GFP (No GFP) and in similar cells in plants containing IRX9-GFP is shown; No GFP (n = 20 gold particles, 277 Golgi, 19 cells, 4 seedlings, 2 high-pressure freezing experiments); IRX9-GFP (n = 410 gold particles, 493 Golgi, 39 cells, 4 seedlings, 2 high-pressure freezing experiments). C, Anti-xylan (CCRC M138) labeling of a Golgi in a SCW-producing cell in a plant containing IRX9-GFP. Black circle outlines a gold particle. Scale bar = 200 nm. D, Percent of gold particles in Golgi cisternae from cis cisternae through to the TGN for anti-GFP (IRX9-GFP) or CCRC-M138 anti-xylan (Xylan). E, Average distance from gold label to the cisterna center and margin. All gold particles were pooled, regardless of cisterna labeled. Means ± 95% CI. Different letters (a to d) indicate statistically significant differences. Statistics = one-way ANOVA with Tukey HSD post hoc (P < 0.05). F and G, Heat map of gold distribution across the Golgi from cis to trans and in 10% blocks of cisternal diameter from the center to the edge of each cisterna. Distribution of IRX9-GFP (F) and xylan (G). H and I, Distributions of IRX9-GFP (H) and xylan (I) adjusted for changes in cisternal width from cis to trans using the average cisternal diameters of early-SCW Golgi. Blocks represent 10% of the cisternal diameter. J and K, Correlation of number of fenestrations (J) or cisternal margin size (K) in each cisterna with amount of GFP (green) or xylan (orange) label in each cisterna; Xylan (n = 136 gold particles, 17 cells); IRX9-GFP (n = 182 gold particles, 33 cells). Data are from 4 seedlings and 2 high-pressure freezing experiments.