Figure 5.

In trichomes, NAP1 transitions from a distributed population of punctae in growing cells from stages 1 through 5 to a reticulate pattern in fully expanded stage 6 cells. A, Immunolocalized NAP1 is concentrated at punctate structures that are distributed throughout a spherical stage 1 (st 1/2) trichome cell. The image shown is the maximum Z-projection of a confocal image stack of anti-NAP1 signal from nearly all of the cell volume. B, NAP1 localization in a cylindrical unbranched stage 2/3 (st 2/3) trichome that is at the transition to branch initiation. The arrowhead indicates the position of a small bulge that defines the position of a newly initiated branch. The confocal image is a Z-projection containing nearly all of the cell volume. C, NAP1 localization in a stage 4 (st 4) trichome that contains a short branch with a blunt tip. NAP1 is localized to punctate structures. The arrowhead indicates a blunt trichome branch tip at the stage when NAP1 is essential for polarized growth. The image is the maximum Z-projection of part of a confocal image stack that contains nearly all of the upper trichome. D, NAP1 localization in a stage 5 (st 5) trichome. NAP1 is localized to punctate structures and diffuse membrane structures. The large elliptical structure in the trichome’s stalk is the nucleus, as indicated by the arrow. The image is the maximum Z-projection of a confocal image stack. E, NAP1 localization in a stage 6 (st 6) trichome. NAP1 shows a reticulate structure and diffuse sheets of membrane. Punctate NAP1 structures were rarely found in this stage 6 cell. The arrows indicate the cell wall tubercles that define stage 6 cells that have ceased cell expansion. Bars = 5 μm in A and B and 10 μm in C to E.