Figure 1.

Root responses and infection development during the experimental time course. Roots of 5-d-old M. truncatula seedlings were inoculated with S. medicae ABS7M constitutively expressing the lacZ gene. Morphological features, including root hair deformations and inner cortical cell divisions, were monitored in the susceptible zone proximal to the root tip across time. A, Uninoculated roots. B, Roots at 0.5 hpi. C, Roots at 1 hpi. D, Roots at 3 hpi. E, Roots at 6 hpi. F, Roots at 12 hpi, G, Roots at 24 hpi. H, Roots at 36 hpi. I, Roots at 48 hpi. J, Roots at 72 hpi. Scale bars = 50 μm.