Hairy roots of L. japonicus Gifu wild-type transformed with the empty vector (EV), pUB:NFR1-mOrange (NFR1), pUB:NFR5-mOrange (NFR5), or pUB:SYMRK-mOrange (SYMRK) were generated. (A) Plot represents the numbers of nodule primordia (white), nodules (light grey) and total organogenesis events (dark grey; nodules and nodule primordia) per nodulated plant formed in the absence of rhizobia at 60 dpt. Number of nodulated plants per total plants is specified under each line label. Black dots, data points outside 1.5 interquartile range (IQR) of the upper quartile; numbers above upper whiskers indicate the values of individual data points outside of the plotting area. Bold black line, median; box, IQR; whiskers, lowest/highest data point within 1.5 IQR of the lower/upper quartile. Plants transformed with the empty vector did not develop spontaneous nodules. (B) Pictures of spontaneous nodules on hairy roots expressing the indicated transgenes taken 60 dpt. Bars, 1 mm. (C) Micrographs of sections of spontaneous nodules on hairy roots expressing the indicated transgenes harvested at 60 dpt. Spontaneous nodules of 10-week-old snf1-1 mutant plants were used as controls. Nodules of 10-week-old untransformed L. japonicus wild-type Gifu 6 weeks after inoculation with M. loti MAFF303099 DsRED contained cortical cells filled with bacteria (brown colour) that are absent in spontaneous nodules. Arrows point to peripheral vascular bundles. Longitudinal 40 mm sections. Bars, 150 µm.