Expression patterns of LjPIN1, LjPIN2, LjPIN3, and LjPIN4 in nodule primordium (A,D,G and J—respectively), 20 dpi nodule (B,E,H and K—respectively) and mature, 54 dpi nodule (C,F,I and L—respectively), obtained by GUS histochemical assays performed on transgenic roots. np—nodule primordium; rc—root cortex; crh—curled root hair; nvb—nodule’s vascular bundle; black thin arrows—cells of root cortex in the division; arrowheads—starch grains; blue arrows—tracheal elements; stars—vascular connection between root’s stele and nodule. Bars: 20 µm (D), 50 µm (A,G,J), 100 µm (B,E,H,K), 200 µm (C,F,I,L).