The OsGEX2 gene promoter confers pollen sperm cell-specific expression in transgenic rice

Authors: Cook, Meridith; Thilmony, Roger

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2012
Publication Date: 3/14/2012
Citation: Cook, M.A., Thilmony, R.L. 2012. The OsGEX2 gene promoter confers pollen sperm cell-specific expression in transgenic rice. Planta. DOI: 10.1007/s11105-012-0429-3.

Interpretive Summary: Rice is one of the most important crops worldwide, providing a dietary staple for much of the world’s population. Biotechnology can help address obstacles to rice cultivation, such as disease and abiotic stresses, as well as enhance traits of interest, such as nutrient fortification. Crucial components of biotechnology are the promoters (or genetic switches) which determine when and where genes are turned on or off. A promoter from rice called OsGEX2 has been isolated and shown to activate gene expression only in the pollen of transformed rice plants. This novel molecular tool will facilitate the biotechnological improvement of rice and potentially other crop plants by enabling the precise control of transgene expression.

Technical Abstract: Expression control elements (i.e. promoters) are crucial components required for the genetic engineering of plants, but relatively few well-characterized organ-specific promoters are available. We have characterized the rice Gamete Expressed 2 (OsGEX2) gene promoter in transgenic rice plants. The OsGEX2 gene transcript was only detected in rice pollen (or mixed tissues that contain pollen) and not found in other organs or tissues. Transgenic rice plants containing an OsGEX2 promoter fused to a GUSPlus reporter gene displayed cell-type specific ß-glucuronidase enzyme activity localized within the sperm cells of rice pollen. This expression pattern was clearly distinct from the uniform reporter gene activity observed in the pollen vegetative cell of transgenic rice carrying the rice Pollen Specific 1 (PS1)promoter. The pollen-specific reporter gene activity in OsGEX2-GUSPlus transgenic plants correlated well with the native gene transcript levels, suggesting that the cis regulatory elements necessary for this specificity are present in the 1.9kb OsGEX2 promoter fragment. The OsGEX2 promoter with its cell type-specific expression will be a useful tool for precisely controlling pollen-specific gene expression in rice pollen and potentially other cereal crop plants.