Figure 3.

Cross-sections of roots from susceptible (YZ—a,b) and resistant (BM13H—c,d) G. arboreum seedlings 7 days after inoculation with BRR spores in sterile culture. The epidermis and cortex became colonized to varying degrees in both accessions, with dark fungal hyphae and cortical blackening generally more extensive in YZ roots. Abundant spores (arrowheads in a) are evident emerging from fungal mycelium on YZ roots. co = cortex, en = endodermis, xy = xylem poles (2 of 5 indicated in c) Bar in a for a–d = 0.2 mm.