Regulation of expression of rice thaumatin-like protein: inducibility by elicitor requires promoter W-box elements.

Rice thaumatin-like protein (Rtlp1) is a high-molecular-weight antimicrobial pathogenesis-related protein that plays a role in plant stress response. This study examines transcriptional regulation of Rtlp1 using wild type and transgenic rice plants carrying a beta-glucuronidase (GUS) reporter gene driven by the Rtlp1 promoter (pRtlp1GUS). The Rtlp1 promoter is induced within 6 h after infection with rice blast fungus (Magnaporthe grisea). The Rtlp1 promoter is also induced by salicylic acid (SA), methyl jasmonate (MeJA), wounding or an elicitor from rice blast fungus. The function of the pRtlp1GUS reporter gene was analyzed by deletion mapping and transient expression assays in cell culture. A 120 bp truncated fusion construct with six W-boxes (5'-TGAC-3') demonstrated a strong dose-dependent elicitor-response. These results suggest that W-box elements are required for the response of the Rtlp1 promoter to fungal elicitors.