Viral promoters have played a decisive role in the production of transgenic plants as gene expression cassettes. To explore the promoter of an Indian isolate of Rice tungro bacilliform virus (RTBV-WB), we employed multiple strategies for its functional dissection. This study led to the discovery of novel regulatory elements in the promoter, especially a negative element (Mathur and Dasgupta, 2007). This negative element was later shown to be active with heterologous genes and orientation-independent (Purkayastha et al., 2010). The commercial implications of the knowledge of this promoter for heterologous gene expression has been recognized and awarded an international patent (US Patent no. 07728122; Eurasian patent no. 013229). We have published a comprehensive review on promoters of geminiviruses, an important group of plant viruses for tropical and sub-tropical regions of the world (Borah et al., 2016).