Figure 7.

Exogenous Application of Iron Enhances the Virulence of Δnps6 Strains to Each Host.

(A) and (B) Application of ferric citrate partially restores the virulence of the C. heterostrophus Δnps6 strain to maize.

(A) Third true leaves of maize cv W64A-N inoculated with the wild-type or Δnps6 (Chnps6-1) strains of C. heterostrophus without (top row) or with (bottom row) 1 mM ferric citrate, 5 d after inoculation. Mock control (right leaves, both panels) were treated with 0.02% Tween 20 solution without (top row) or with (bottom row) ferric citrate.

(B) Average vertical lengths of lesions are shown for each strain and for each treatment. Error bars show 95% confidence intervals. Application of iron led to a statistically significant enhancement of virulence of the Δnps6 strain (P < 0.05) (lesion size [mm]: Δnps6 = 1.68 ± 0.17; Δnps6 with iron = 2.75 ± 0.21).

(C) and (D) Application of Fe(III) EDTA enhances the virulence of the C. miyabeanus Δnps6 strain to rice.

(C) Rice leaves drop-inoculated with wild-type (left) and Δnps6 (Cmnps6-2) strains of C. miyabeanus, with and without exogenous application of 0.5 mM Fe(III) EDTA. A mock-inoculated control is shown at right.

(D) Average vertical lengths of lesions formed by the wild-type or Δnps6 strains with or without iron treatment. Error bars indicate 95% confidence intervals. A statistically significant change in the virulence of the Δnps6 strain was observed when iron was supplied (P < 0.05).