Fig. 3

PAS rhodamine-123 counterstained with calcofluor white differentially labels, and shows distinct layers in, infection threads. M. truncatula root hairs stained with PAS rhodamine-123 (magenta) then with calcofluor white (green). a Root hair infection threads (arrow) inside a root hair are stained with rhodamine-123 whereas the dominant stain in cell walls is calcofluor white. b–d Cortical infection threads show two distinct layers, an outer layer stained with calcofluor white, and an inner layer stained with rhodamine-123. In (b) two infection threads exit the root hair to traverse the subtending epidermal cell and emerge in the cortical cells below. c Infection threads in root cortical cells. d Optical cross sections of infection threads in root cortical cells. e Infection chambers are also differentially labelled with rhodamine-123 (arrows). Images a and b are maximum projections of 60.01 µm, and 9.99 µm confocal z-stacks. All images were captured using a 63× objective. Scale bars = 25 μm. rh root hair, cc cortical cell, cw cell wall