<i>graminearum</i> bta1 mutants show reduced virulence in maize stalk infection and reduced growth on phosphate depleted media.

<p><b><i>F</i></b>. (A)-(C) Maize stalks infected by wild-type or mutant <i>F</i>. <i>graminearum</i> at the indicated number of days after inoculation. Note that more vascular strands are visible in the stalk infected by wild-type <i>F</i>. <i>graminearum</i> than that infected by mutant <i>F</i>. <i>graminearum</i> in (B). White arrows point to hyphae (in pseudo pink). Blue arrows point to debris-like structure in host cells. (D) Supplementation with KH₂PO₄ increased lesion size caused by the bta1 mutant strain. Different letters indicate statistical differences among the strains, according to Tukey’s multiple comparison test (P = 0.05), n = 3 independent experiments. (E) Fungal growth after 2 days of culture on various media. MM: minimal medium, −P: minimal medium lacking phosphate. −P^2nd: hyphal disks from −P medium were transferred to fresh −P medium plates to exhaust endogenous phosphate. Statistical analysis for colony radius and relative hyphal densities are charted at the bottom of the panel. The radius was measured at 1 day after transfer onto the −P^2nd medium. The relative hyphal density was determined using ImageJ software by measuring the gray value of the same positions of each fungal colony on pictures (subtracted from the respective background gray value). *Significantly different from wild type (P < 0.05) according to Student’s <i>t</i> test, n ≥3. Error bars denote SE.