Figure 5.

In Situ Hybridization Analysis of MtENOD40 mRNA in Roots of Wild-Type and B85 (Locus 4) Plants in Response to S. meliloti.

Roots were hybridized with α-³⁵S-UTP–labeled MtENOD40 RNA probes 48 hr after spot inoculation with S. meliloti GMI5626. Data are presented only for the antisense probes; no hybridization signals were detected with sense probes.

(A) and (C) Bright-field microscopy; hybridization signals are visible as dark spots.

(B) and (D) Dark-field microscopy; hybridization signals are visible as white dots.

(A) and (B) Longitudinal section of a wild-type root showing MtENOD40 RNA localized in the cortical and pericycle dividing cells of a nodule primordium.

(C) and (D) Longitudinal section of a B85 root, showing neither cell divisions nor MtENOD40 expression.

CC, cortical cells; arrows, pericycle. .