Fig. 7

The Medicago truncatula protein Medtr1g073320 is regulated in response to rhizobia and co-localizes with callose at plasmodesmata. The in silico proteome PIP1 for Medicago truncatula was generated using the pipeline (see Additional file 1: Table S8). a Expression analysis of PD candidate genes isolated in PIP1-A and PIP1-C co-regulated with SUNN and MtBG2 in response to nitrate and rhizobia inoculation. Differential gene expression (log₂FC) was determined using public microarray data of experiments relating to nitrate and rhizobia inoculation in root tissue (see Additional file 1: Table S7 for information on selected microarrays). Expression 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 [54]. Rows are ordered by hierarchical clustering (dendrogram on the left). 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. Red arrow indicates the position of MTR_1g073320. b-i Confocal microscope images of roots expressing Medtr1g073320 fused with YFP (green) counterstained with aniline blue (grey in c, magenta in e, h) to reveal callose. Images shown in b, d, and g were obtained with excitation laser 561 nm (YFP). Images shown in c, e and h were obtained using excitation laser 405 nm (aniline blue). Merged images are shown in (f) and (i). Co-localization events are highlighted with arrows. Panels d-f are a magnification of the area highlighted by the white box in (b-c). Panels g-i are magnification of the area highlighted in the panels d-f. Scale bar = 20 μm. See also Additional file 2: Fig. S7