Figure 3. (A) Distribution of fungal mycelium and spores on the root surface and in the root material. The seedlings were either co-cultivated with P. indica on the fungal lawn for 7 d (upper part, fungal lawn), or co-cultivated with the fungus under beneficial conditions for 7 d (lower part, beneficial interaction). After staining of the fungal material, light microscopic or fluorescent pictures were taken from the root surface or from the central part of the root. Note the high concentration of spores and mycelium on the surface of the roots grown on the fungal lawn, which are not detectable inside of the roots. Under beneficial co-cultivation conditions for 7 d, spores are not yet formed, but the mycelium is detectable on the root surface. (B) The amount of the fungal ITS cDNA relative to the root GAPC2 mRNA. Arabidopsis seedlings were co-cultivated with P. indica under beneficial conditions or on the fungal lawn for 7 d. After extensive washing of the roots, the mRNA was extracted and the amounts of the fungal and plant genes were determined by quantitative RT-PCR.