Figure 7.

Associations between toxin production in vitro, in planta and pathogenicity on rice. S. oryzae isolates were grown for 7 days on PDA. The concentration of cerulenin (µg/L) and helvolic acid (µg/L) in the extract of the culture was measured with liquid chromatography high-resolution mass spectrometry. When 7 weeks old, rice plants were inoculated with the same strains of S. oryzae using the standard grain inoculum technique. At 6 DPI, cerulenin (ng/g) and helvolic acid (ng/g) levels were analysed in sheath samples and the disease was scored by measuring the lesion area (mm²). Scatterplots show the associations between pathogenicity and helvolic acid and cerulenin levels in vitro (A, B) and in planta (C, D) and between the production in vitro and in planta of helvolic acid (E) and cerulenin (F). Isolates of Groups 1, 2 and 3 are represented by, respectively, green, orange and blue dots; significant linear correlations are represented by the linear regression curve in red.