40µm

At MPB2C-RFP + ER-GFP

36h 80µm

At MPB2C-RFP + Talin-GFP

At MPB2C-RFP punctae are not part of the actin filaments taggedby Talin-GFP (left panel: magnification of the indicated region).

At MPB2C-RFP signals do not coincide with ER-GFP and Talin-GFP

At MPB2C-RFP punctae are inproximity of but not coincidingwith ER structures tagged byER-GFP.

At MPB2C-RFP + Talin-GFP

Subcellular distribution of MPB2C

80µm

At MPB2C-GFP +Nt MPB2C-dsRED

At MPB2C -GFP

80µm 160µm

At MPB2C-GFP

48h24h 24h

40µm

KN1-GFP At MPB2C-RFP MergedCoexpression of At MPB2C-RFP with KN1-GFP

Cortical view of an epidermalArabidopsis cell expressingAt MPB2C-RFP and KN1-GFP . Bo th cons t ruc t scolocalize at punctae and fil-amentous structures resem-b l i ng m ic ro tubu les(arrowheads). A KN1-GFPsignal is also present in thecytosol (triangles).

Supplemental Figure 1. Subcellular distribution of At MPB2C and Nt MPB2C, GFP-KN1, ER-GFPand Talin- GFP expressed in epidermal cells.Arrowheads indicate colocalization of GFP and DsRED/RFP signals. Triangles indicate GFP alonesignals. Red: DsRED/RFP; Green: GFP; Blue: chloroplast auto-fluorescence; Orange/White: overlap-ping signal of DsRED/RFP and GFP.

Supplemental Figure 1, Winter & Kollwig et al. (2007)

Supplemental Figure 2. Comparison of the relative At MPB2C and GL1-KN1HDexpression levels to trichome numbers in Pro35S:At MPB2C transgenic trichome rescuelines. The number of trichomes appearing on trichome rescue lines (3rd and 4th leaf;n>20) were analyzed. Blue columns show the average (bars: standard deviation) oftrichome numbers. Note that At MPB2C and GFP-GL1-KNHD RNA expression levelswere measured in RT-PCR assays with RNA harvested from pooled plants. The relativeAt MPB2C RNA levels were calculated against GFP-GL1-KNHD RNA expression sig-nals (=100%) after equalizing both against endogenous Actin RNA signals. Note that thetrichome numbers vary slightly from that shown in Table 3, as plants grown at a differ-ent time were used for the analysis.

Supplemental Figure 2Winter & Kollwig et al. (2007)

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Supplemental Figure 3Winter & Kollwig et al. (2007)

80µm

Trichome rescue parent line (GFP-GL1-KN1HD)

Trichome rescue line (I3.12.3) trans-formed with Pro35S:At MPB2C

80µm

Supplemental Figure 3. Confocal images of GFP-GL1-KN1HD signals detected inleaves of Arabidopsis trichome rescue lines. The GFP-GL1-KN1HD signal appearsexclusively in punctae at cell walls, which are in contact to adjacent cells typical for aPD association (arrows; left panel). Pro35S:At MPB2C transgenic trichome rescue lines(right panel) show green fluorescent signals exclusively in nuclei (N). Note that confocalsettings (pinhole, gain and z-axis) were the same for both images.

SUPPLEMENTAL MATERIALS (Winter et al. 2007)

Supplemental Table 1. Example for the Yeast two-hybrid interaction categorization as

shown in Figure 1 B.

BD fusion AD fusions ß-GAL (SD)a Interaction

KN1∆C w/o <2 -

KN1∆C KN1 944 (±80) +

KN1∆C BEL1 1,020 (±54) +

KN1∆C NtMPB2C 97 (±16) -/+

BD empty KN1 <2 -

BD empty BEL1 <2 -

BD empty NtMPB2C <2 - a Mean of ß-gal specific activity (units/mg protein) measured in the lysate of

more than four transformants. SD: standard deviation