Quantification of chitin in the cell wall obtained from the wild‐type EV‐MIL31 (WT), the strains carrying a single Nox gene mutation (ΔnoxA, ΔnoxB and ΔnoxR), the rescued strains (CpB24 and CpR40) and the NoxA NoxB (ΔnoxAB) and NoxA NoxR (ΔnoxAR) double‐mutant strains of Alternaria alternata. Chitin was extracted with HCl and determined by measuring the acid‐released glucosamine from chitin using p‐dimethylaminobenzaldehyde as a chromogen. Except for CpB24 and CpR40 strains, all strains were tested at least twice. Means indicated by the same letter are not significantly different from one another, P < 0.05.