Fig. 5

Measurement of CDR in planta. Wildtype and SSO1-GFP expressing strains of Z. tritici isolates IPO323 and IPO94629 were inoculated onto leaves of the wheat cultivar Galaxie. Leaf samples were harvested from nine independent plants for each wildtype isolate at 3 and 12 days post inoculation for chitin and DNA quantitation and CDR calculation (A; values are means and error bars show SE), while leaf samples inoculated with isolates expressing GFP were harvested at the same time points and visualised by confocal microscopy for the calculation of polarity indices (B; IPO323, n = 21 (0 dpi); 52 (3 dpi) or 46 (12 dpi) cells across 3 fields of view; IPO94629, n = 23 (0 dpi); 52 (3 dpi) or 44 (12 dpi) cells across 3 fields of view). Both isolates germinated on the wheat leaf, with hyphal cells visible from 3 dpi in IPO323 and at 12 dpi in IPO94629; representative images are shown in C. CDR increased over time for both isolates (A; ANOVA, P < 0.0001—differing letters above bars represent significant differences in Tukey’s simultaneous comparisons), but faster for IPO323, which could be seen to germinate earlier (C). As with in vitro samples, there was a close, linear relationship between CDR and polarity index (B; P = 0.00024, R² = 0.9747)