Figure 5.—

Biotic stress response in Fusarium graminearum-inoculated barley spikes. (A) RNA gel blot analysis of combined GerB and GerF (GerB-F) expression levels in lemmas. Detached spikes were either mock-inoculated (CON) or inoculated with F. graminearum (INF) for 24 or 48 hr. Blots were rehybridized with a barley PR-1 cDNA probe (positive control) and a barley 18S probe (loading control). (B) Fold induction after F. graminearum inoculation. Bars represent induction levels observed for GerB-F (solid) and PR-1 (shaded) in inoculated spikes relative to control spikes. GerB-F and PR-1 signals (counts per minute) were normalized using the corresponding counts per minute of 18S. Normalized signals for inoculated spikes were divided by the normalized signals of control spikes to obtain fold inductions. (C) cDNA–SSCP analysis of GerB and GerF expression in lemmas of mock-inoculated (CON) and F. graminearum-inoculated (INF) spikes. WC, no DNA template control; GerB and GerF, plasmid controls. Relative transcript levels (%) and corresponding standard deviations (s.d.) were determined by Instant Imager analysis.