Fig. 8. Resorption of starch in Orobanche infected by Fusarium oxysporum. Starch grains (which appear white in polarized light) are seen in Orobanche tubercle sections in controls (A and B) and at 1 h after F. oxysporum inoculation (C), but were greatly depleted by 3 h (D). Starch stained brown–black with iodine and was plentiful in control tissues (E), much less plentiful in inoculated tubercles at 3 h (F), and absent by 24 h (G). The vascular system (red arrows) observed under polarized light was fluorescent in all samples, although the intensity varied among the tubercles. Yellow and blue arrows indicate starch grains. Bars = 200 µm.