Fig. 4

Promoter activity as indicated by GUS staining in immature and mature nodules on transgenic plants expressing selected promoter:GUS constructs. Transgenes are a–d pLeExt1:GUS (line LIG29-2); e–h pAtCortex:GUS (line CoG11-6); i–l pAtE29:GUS (line 29G4b-5); m–p pAtS13:GUS (line 13G26b-28) and q–t pAtS18:GUS (line XG5A-5). Plants were inoculated with M. loti at 1 week of age and harvested at 2 weeks post germination. Representative GUS stained immature (a, e, i, m, q) and mature (b–d, f–h, j–l, n–p, r–t) nodules. Entire mounts (a–b, e–f, i–j, m–n, q–r) or cross sections (c–d, g–h, k–l, o–p, s–t) are shown. Cross sections are 7–8 µm microtome sections of resin (Kulzer Technovit 7100) embedded roots stained with 0.1 % Ruthenium Red. Scale bars d, h, l, p, t 20 µm, else 50 µm