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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Fruit Crops through Functional Genomics and Breeding

Location: Appalachian Fruit Research Laboratory

Title: Highly interactive nature of flower-specific enhancers and promoters, and its potential impact on tissue-specific expression and engineering of multiple genes or agronomic traits

Authors
item Wen, Zhifeng -
item Yang, Yazhou -
item Zhang, Jinjin -
item Wang, Xiping -
item Liu, Zhongchi -
item Singer, Stacy -
item Yang, Yingjun -
item Liu, Zongrang

Submitted to: Plant Biotechnology
Publication Type: Review Article
Publication Acceptance Date: April 22, 2014
Publication Date: June 4, 2014
Citation: Wen, Z., Yang, Y., Zhang, J., Wang, X., Liu, Z., Singer, S., Yang, Y., Liu, Z. 2014. Highly interactive nature of flower-specific enhancers and promoters, and its potential impact on tissue-specific expression and engineering of multiple genes or agronomic traits. Plant Biotechnology. DOI: 10.1111/pbi.12203.

Technical Abstract: Molecular stacking via a single transgene enables multiple traits being engineered efficiently in crops. However, whether distinct plant promoters co-existed in the same transgene could, like their mammalian counterparts, mutually interact or interfere remains unknown. In this study, we devised a novel approach to investigate the enhancer- and promoter-promoter interactions in transgenic plants, and demonstrated that three of four flower-specific enhancer/promoters tested were, even located at 2.5 kb apart, capable of activating the pollen- and stigma-specific Pps promoter driving a cytotoxic DT-A in the tissues other than pollen and stigma, as reflected by tissue-specific DT-A up-regulation and ablation. We showed that the NtAGI1 enhancer activated petal-, stamen- and carpel-specific DT-A expression and ablation in an orientation-independent manner, and this activation was completely abolished by the insertion of an enhancer-blocking insulator, EXOB, between them, indicating that NtAGI1 directly acts on the Pps promoter rather than DT-A. AGL8 and AP1Lb1 but not AP1La promoters similarly activated distinct tissue-specific DT-A expression and ablation patterns, with the former inciting global growth retardation while the latter ablating the apical inflorescences. The enhancer/promoters’ specificity appears to dictate their tissue-specific activation action but in a strength-/activity-dependent manner. Our work presents the first evidence that plant-derived, flower-specific enhancer/promoters can distantly interact in transgene, which could pose a potential problem for tissue-specific engineering of multiple traits using gene-link approach, and entail taking necessary measures (e.g. use of genetic insulators) to prevent such interaction in molecular stacking gene constructs. Practical and fundamental significance of this work will be discussed.

Last Modified: 11/24/2014
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