Creation and analysis of a novel chimeric promoter for the complete containment of pollen- and seed-mediated gene flow

Authors: Liu, Zongrang; ZHOU, CHANGHE - WEST VIRGINIA UNIVERSITY; WU, KEQIANG - WEST VIRGINIA UNIVERSITY

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2008
Publication Date: 3/4/2008
Citation: Liu, Z., Zhou, C., Wu, K. 2008. Creation and analysis of a novel chimeric promoter for the complete containment of pollen- and seed-mediated gene flow. Plant Cell Reports. 27:995-1004.

Interpretive Summary: The concerns on pollen- and seed-mediated gene flow and potential food safety of transgenic crops are growing and spurring intense debates, which potentially impact the confidence of both farmers and consumers in adopting and accepting transgenic crops and foods. Thus, effective technology is needed to address the current concern on transgene flow from GM crops into wild type or their wild relatives. In this study, we created a novel chimeric pollen, stigma and fruit-specific (PSF) promoter by molecular fusion of the distinct cis regulatory elements identified in several promoters, and used it to target the retardation of male and female gametes or organs for containing pollen- and seed-mediated transgene dispersal. Our study demonstrated that the newly created PSF promoter acquired strong expression activity specific to anther, pollen and stigma tissues, and irreversibly ablated them in transgenic plants when fused to the cytotoxic gene DT-A, which prevents gene flow in the crosses of transgenic plants with their wild type.

Technical Abstract: Effective technology is needed to address current scientific concern on transgene flow from GM crops into wild type or their wild relatives. The key to successfully preventing pollen- and seed-mediated gene flow is largely dependent on the availability of highly tissue-specific promoters that can target the expression of lethal or dominant-negative genes in male and female gametes or tissues essential for the pollination and fertilization process. Here, we report the creation of a chimeric pollen, stigma and fruit-specific (PSF) promoter by molecular fusion of the distinct cis regulatory elements identified in several promoters. Transgenic analysis demonstrated that the PSF promoter acquired pollen- and stigma-specific properties from LAT52 and SLG13 promoter elements but not the fruit-specific property from AGL5 element. The PSF promoter, when fused to the cytotoxic gene DT-A, is much stronger than its progenitor promoter SLG13 in targeting the retardation of both male and female organs. Genetic analysis showed that PSF::DT-A transgenic plants are sterile in both incross and outcross populations, which prevents gene flow by both male and female gametes under a laboratory condition. This strategy has the potential application for gene containment in those species (e.g. forest, ornamental plants) whose products serve a non-food purpose and are discussed.