Expression of GhWRKY15 in response to different fungal infections and hormone treatments. Approximately one-week-old cotton seedlings were used for all treatments. For the fungal inoculation, the roots of the cotton seedlings were dipped into conidial suspensions of C. gossypii (A), F. oxysporum f. sp. vasinfectum (B) or R. solani (C) (105 conidia/ml). The signalling molecules used were 2 mM SA (D), 100 μM MeJA (E) and ET released from 5 mM ethephon (F). Whole seedling plants were collected for RNA extraction. Ethidium bromide-stained rRNA was included as a loading control.