Fig. 4

The expression of PD candidates and callose deposition is regulated in response to osmotic and salinity stress. a Differential expression (log₂FC) of genes in PIP1-A, PIP1-C and verified PD tables grouped in clusters 87 and 100 (see Additional file 1: Table S6) was determined using public microarrays (see Additional file 1: Table S7 and Additional file 2: Figure S3). Profiles range from blue to red (downregulated to upregulated in relation to control). Column labels at the bottom show ArrayExpress accession codes followed by a reference number as listed in Additional file 1: Table S7 [54]. Rows are ordered by hierarchical clustering (dendrogram). Asterisks in cells on the right denote predictions on membrane targeting features or verified PD localization. SP = Signal peptide, GPI = glycophosphatidylinositol anchor, TM = transmembrane domain. Cell colour above each column represents the material sampled as indicated in the legend. b-g Aniline blue staining of 7 days old Arabidopsis roots grown on ATS (b, d, f) or ATS with 75mM NaCl (c, e, g) media. The pictures are confocal images of root tips (b-c) and high magnification sections in the differentiation zone (d-g) of roots stained with aniline blue (405 nm, blue; d-e) and with propidium iodide (561 nm, shown in grey; f-g). Arrows in d-e show punctate pattern of callose in cell walls reminiscent of PD. The pictures are representative of at least three independent biological replicas (see Additional file 2: Figure S4). Scale bar (b-c) = 50 μm; (d-g) = 20 μm