Fig. 1. S. sclerotiorum growing endophytically in wheat roots.

a Visualized by confocal microscopy, hyphae of strain DT-8VF^RFP in a segment of a rootlet stained with wheat germ agglutinin (WGA). a2 Z-stack images to further show the hyphae inside the rootlet of a1; Scale bars for a1 and a2 are 200 and 50 µm. b Visualized by colloidal gold immunoelectron microscopy, hyphae of strain DT-8VF^RFP in the intercellular spaces of roots probed with the anti-mCherry antibody (b1), (b2), and (b3) are enlargements of the boxed regions (i and ii) in b1. c Visualized by scanning electron microscopy, hyphae of strains DT-8VF and DT-8 in the intercellular and intracellular spaces of roots (indicated by arrows). c1 Transverse section of a rootlet of DT-8VF-treated plant; c2–c4 enlargement of the regions in dotted boxes (i–iii) in c1; c2, c4 a single hypha in a root cell; c5 transverse section of a rootlet of strain DT-8-treated plant, showing hyphae in the intercellular and intracellular spaces of roots; and c6 enlargement of the regions in a dotted box (iv) of c5. No hyphae were observed in root of noninoculated wheat (CK), its SEM pictures were presented in Supplementary Fig. 3. Seedlings germinated from surface-sterilized seeds were inoculated with strains DT-8VF and DT-8 and allowed to grow for an additional 15 days on MS medium in a sterile culture bottle before sampling.